Factory:  Corner Steyr & Alfa Sts 
Aureus Industrial sites 
Email: info@keramicalia.co.za
Website: www.keramicalia.co.za
Cell: Dave  082  808 4757
Email: keraccounts@iafrica.co.za
Accounts: Myrtle Wakeford
Tel: (011) 764 2139
Tel: (011) 412 3261
P O  Box 2288
Wilro Park,1731



Dear readers,

Research and Development.

Keramicalia’s primary activity is research and development.  My passion is solving problems.  Manufacturing is a sideline to finance our R&D.  I don’t like running the business and would like to spend all my time solving problems and developing new materials.

After 40 years of R&D I have compiled a vast range of formulations over more than 1000 projects.  Consequently devising a new material is very quick.  The R&D has already been done and meticulously filed and recorded, with tens of thousands of samples.  Every new project is already nearly completed.  It draws on technology developed over previous projects.  A new material may be based on up to four previous projects.  I pull out the files and sometimes the samples, analyze them and write out my best guess  of the ideal formulation for the new material.  Sometimes the first formulation I write down and test is exactly right.  Studying the precursors takes about 4 to 8 hours.  However, the development of the precursors took months and all of them relied on prior developments which also too months.  So the new material developed in a day, actually took several years.

People not involved in R&D go to universities, CSIR, Mintek, etc. and pay a lot of money for young graduates to spend years developing technology.  The client pays for the salaries and equipment used.  The idea of getting the same result in one day but paying hundreds of thousands of Rands for it is something they cannot accept.  Paying tens of thousand of Rand per month over several years is something they can understand and accept.

My attempt at solving this problem is “Value based R&D.”  Suppose the client wants to manufacture pizza ovens.  There are already many on the market and prices are similar.  The client therefore needs a competitive advantage.  I list the important aspects and put values to them.

For example:

  • Fuel consumption:  If I halve it the client pays me R20 000.  Equal the competition, no charge.  Double the fuel consumption I pay the client a penalty of R20 000.
  • Weight: If it is easy to pick up and carry home, it sells easily.  If I make it 30% lighter I charge R10 000, 50% lighter I charge R20 000.  If it is heavier I pay a penalty of R5 000 per 10% heavier.
  • If it is the best looking oven I get another R10 000 and if it is uglier than average I forfeit R20 000.
  • If production takes 1 man day I earn R20 000, if it takes twice as long as the competition’s I forfeit R30 000.
  • Time to develop it: 6 months break even, I get R5 000 per month early and pay R5 000 per month late.

Lastly but most importantly is the material cost.  If I halve it I get R70 000, double it I pay a penalty of R100 000.

The client then evaluates my proposal according to his perceived priorities and makes a counter proposal.  The aspects of performance are carefully defined to be measurable.

If I make a mess of it the client walks away with a lot of money to compensate for my wasting his time.  If I do a brilliant job I get a lot of money and the client gets a product which he can churn out and fast, it sells like hot cakes and his profit margins are large.

Unfortunately, most clients can’t get their heads around this concept and usually walk away from it.

Sometimes the project is so novel that it is impossible to tell if it is achievable.  In this case we do a phased R&D proposal.

For example:

  • Develop a material to meet the required service temperature and required thermal insulation. A price is set for this goal and paid once the material is proven.
  • Find a method of manufacturing the difficult shape required.
  • Next phase is to make sure it can survive the chemical environment for a defined length of time. Etc. etc.  My favorite furnace manufacturer is amenable to this format and it is a pleasure doing business with them.

Our IT Manager, Dawné Willis is a friend of Antoinette, the puppeteer who owns and manipulates Liewe Heksie.  Antoinette still does puppet shows, makes puppets and launches social upliftment programs.  The latest one is JOLLY BURGERS, handmade puppets shaped like burgers with ethnic traditional beading and faces.  She uses them as an educational aid for reading, learning language skills, translations from all the traditional languages in South Africa for pre-school learners through to grades R upwards.  This aids both the teacher and pupil to bridge the gap to understanding and speaking languages which is sorely lacking in our country.  Antoinette has the ability to motivate and excite the learners with this innovative educational concept.  She wants to set up workshops for thousands of jobs to make millions of puppets for every learner to facilitate the language barrier and uplift the parents, communities and education institutions  to a far better understanding in languages through this exciting medium.  The materials and  kits to make the burgers are supplied and delivered  by Antionette which is  included in the  workshop forum to instruct participants on making the Jolly Burgers.  This is to enable job creation for which communities, old age homes, both young and old so that everyone benefits from by earning an income for each Jolly Burger made  the participant will receive payment.  This is an ongoing project with orders streaming in and so many hands make light work. Antoinette can be contacted on 0716587461 or email Antoinette Pienaar at  This email address is being protected from spambots. You need JavaScript enabled to view it. for any organization, community or individuals wishing to participate.

Antoinette asked me to make puppet heads and gave me a model. It’s just the sort of thing I love getting involved in.  I struck some complex problems.  I commenced with documenting the process with photos, but the process was changing as I progressed.  Eventually I had the production molds and thought it would be plain sailing from hereon.  However, I could not develop a material light enough!  I was discussing polyurethane with Mike Fellows-Smith and started making a high pressure mold.

I was using Plasticast and Plastiperl for their resilience, but couldn’t get a light enough mix. I noticed that I could get a viscous fluid which set very fast and ended up very hard and tough.  I tried pouring the fluid into my Multimould rubber molds and turning them to coat the inside of the mould.  To my surprise, it worked beautifully!  The head needs a dowel sticking out of the neck.  I put the dowel through a rubber mat and after the mould is coated I put it down on the mat and the last bit of mix flows down onto the rubber mat and onto the stick.  The head needs 3 other string attachment points.  These gave some problems, and we ended up fitting wire loops into the mould before filling the rotation moulding mix.  I called the material “Puppet Head” temporarily while thinking about an appropriate name for a rotational moulding compound. It was Barbara Harper who discovered the material and fell on it with glee, because it was absolutely perfect for her mosaic tortoises which she makes.  I banged two reject puppet heads together to test their strength and it was rather impressive.  It struck me that “Tortoiseshell” would be an apt description of its properties so the name stuck.  We could make 20 puppet heads per day with our 3 moulds.


Molders usually want something lightweight, cheap, strong with good detail and fast production.

Lightweight and strong work against each other.  So does lightweight and good detail.

We have developed a complete solution for you.  It is called Tortoiseshell, because it has similar properties of resilience and is non brittle.

Tortoiseshell coatings are completely hollow with a thin film of high quality hard but tough material.  This is achieved by the process of rotational molding.  You make a mold of Multimould Green.  Pour the 60:40 powder to resin into the mold and rotate the mold so that every surface is covered.  You must mix very quickly and pour within 20 seconds.  The mix sets very fast.  You can strip after 2 hours.

Casting puppet heads we achieved an apparent density of O,31 G/cmᶟ.

Development No:  1682

19 October 2017

Dear readers,

Every year the engineering faculty of University of Johannesburg holds a “Concrete boat race”. Teams consist of 7 students who are required to build a “concrete boat” using Portland cement. Students are also required to find a sponsor from the industrial sector to finance the project. This year the boat design had to be a Makorro.




You are a project team member within a company specializing in the design and development of specialized water craft. Your company is approached by the Government of Botswana to design, develop and construct a concrete prototype of an environmentally sustainable two-man open top makorro to be used in the Okavango Delta to transport tourists (one tourist per makorro). A makorro is defined as a lightweight narrow boat, typically pointed at both ends and open on top, propelled by a standing or kneeling pooler facing the direction of travel using a slender pole or single paddle. The client requires the prototype to be tested in South Africa at a watersports event to be held on Saturday the 14th of October 2017 at a location to be disclosed in due course. Mr Kruger at the University of Johannesburg is appointed by the client as the coordinator of this project on their behalf.


I opted to sponsor a team to build a Makorro boat with a polystyrene shell, covered in our “ Boat Cement”, impregnated into Geotextile.

Our boat was the best resemblance of a Makorro ad we were the only team that managed to have one paddler standing. Our team were the best dressed and showed the most spirit, therefore were awarded the “Carnival” trophy. We won the second prize of R4000 for construction and third place in the overall race. (In one heat, all 5 boats competing sank). We left with the most medals.

Practising @ Florida LakePractising @ Florida Lake

Boat, decorated

Prize Giving Ceremony

I think this is a great experience for engineering students to actually design and build something. I think they learned a lot.

Best regards,
Dave and the Keramicalia team.

3 August 2017

Dear readers,

I was surprised to find I have never written about Keraforce before.  It all started on 18 August 2011.  Rein Buisman wanted lightweight rigid pipes.  I showed him one of my lightest materials and one of my strongest materials.  He said “Why don’t you mix the two together.”  I promised to try it though it made no sense to me.  When I mixed the two together the mixture ran like water so I concluded “Well that’s truly buggered now.”  The next morning it was rock hard!!  I was flabbergasted.  It was just what Rein needed, so I named the material Reinite. 

It continued to do amazing things, with a bit of adjustment here and there.  I found it reaches new heights as a composite.  I tested it in various types of fibreglass and textiles and after covering just about every type of textile I chose the geotextile Bidim A2 as the best carrier.  We now call the powder Reforce, the liquid Reinite Binder and the composite Keraforce.  Then I discovered I could make a magnificent engineering material by covering polystyrene with Keraforce.  It is extremely light, very rigid and strong.  With the added property of thermal insulation it was a natural choice for housing.  

My late friend Paul Olver brought Liezl Kok to see it.  She immediately registered a company Biohabitat to market the housing.  Our first house was a small one with a mezzanine bedroom for the kids.  It had two skylights and the atmosphere, particularly the temperature, was very appealing.  The biggest advantage was that it was factory built, and assembled on site in one day.  That means you lock it up that night and there is nothing on site to steal.  We found that you cannot buy a stand in the townships from the municipality.  (I now sympathise with squatters.)  Our first house was made of corrugated panels which are quite strong.  Unfortunately our target market felt it resembled corrugated iron and rejected it on appearance.  I discovered that flat sheets of thicker polystyrene work out cheaper than the corrugated model.  I worked closely with Technopol and we discovered that a 150mm thick roof panel 1 metre wide supported at a 2m interval takes nearly a ton before it breaks!  We now use them unsupported over 5 metres.

In 2013 I started a 3 storey house in my factory grounds.  For a foundation I used polystyrene “floats” 250mm x 250mm x 1m, joined together with Keraforce.  I placed this right on top of the ground, thinking I would watch it sink in every time the ground got saturated with water.  It still hasn’t sunk in.  The building inspector banned my third storey, but Zorro built me a sort of attic in the roof.  Call it a 2 and half storey.  I am living in the house to learn the ins and outs.  It has a nice round fireplace in the centre of the ground floor.  It gives radiant heat in all directions.  It took a lot of modification and experimenting to get it smoke free.  Only one component of the fireplace was made of refractory, and it was the only one that failed.  Now the whole system is Keraforce.  

Some customers have built houses with Keraforce.  I sent a big truckload up to the Zambezi river.  Recently I got an order from Lere Saunderson for a house.  One storey plus a mezzanine bedroom.  I had less than a month to build it.  It was very hectic but I managed to complete it in under a month.  Costs are about R1700/m², compared to about R2400/m² for conventional building.

I would like to see Keraforce used extensively as a replacement for fibreglass.  It is not messy, just wipe the bench with a wet cloth.  It is not irritant, no carcinogens, not sensitive to timing when laminating, UV immune, fireproof,  hard and rigid.  I use Keraforce for just about everything these days, see the brochure attached.  Another lucrative application would be repair of sagging roof trusses.  Just jack them back into place and wrap them with Keraforce and they will be as good as new.   I built a large afdak behind the factory with thoroughly rotten wood as the beams, wrapped with Keraforce.  It is working.  You can see three Keraforce structures at my factory on Google Earth.

Marelise did some marketing.  Unfortunately she had to leave to join her husband in Lichtenburg.  I miss her terribly.

Wishing you all the best,

Dave Onderstall.


Hi Guys,

This newsletter is quite different. It’s about my holiday! I hope my holiday was sufficiently different not to bore you. This didn’t start out as a newsletter.


Flew down, stayed with Nikki and Gina.

Monday morning, excited to see other burners on the road. Got dryer and more desolate. I didn’t realize they chose the purest desert.

The structures left me dumbfounded. I had no idea they were THAT huge. The thousands of man months worked on them is incredible. Even the Rands cost is staggering. Nikki was right, this is just my scene.

Nikki invited me, bought tickets, and then it clashed with an outing to Paulo’s farm to scatter Judy’s ashes. Nikki couldn’t get any more leave, already taken 28 days.

The costumes were way beyond my expectations. I felt naked being unadorned. I made a donkey hat, which was called an Aardvark and a mouse. I took a bit of Keraforce and stuff to make faerie wings, but didn’t use it apart from my hat.

I didn’t like the police presence. 95% of the “music” was rave. This was a huge disappointment. You couldn’t call Afrikaburn a hippie event.

The Mutant Vehicles were amazing, 81 of them, to carry you around the large area. About a third of the burners had their own bicycles. I latched onto a steam engine at its crew, including Conrad the blacksmith artist.

I didn’t know ANYBODY at Afrikaburn. However, your camp neighbors are all nice. Frank and ….. Afrikaners. Derek, Sharon, Dougie and Paula practically absorbed me into their camp. Can’t work out the relationships here. Ian behind me helped peg my tent.

Roland & Claire provided a landmark with lights on a mast on their Landrover. Most people were lost for hours, coming back at night.

First I camped where there was a lot of open space. Then I noticed on the map I was next to a “Loud Zone”. I packed up and moved on Tuesday morning. I was the first illegal at the end of Xanado rd. Every time I came back the camp had extended way past me and I had difficulty finding my tent. There were 11700 burners. That’s a hell of a big camp.

I was fascinated by the rocks. They are deeply fissured and hardened by iron oxides.

I wanted to bring a truckload back.

The desert gets very hot in the day and bitterly cold at night. I was up before dawn making my camp fire every morning. You may not make a fire on the ground, but I found a piece of galvanized iron which I placed on rocks.

I drank a fair amount but never got drunk. I think I have been there, done that. Ideally I would like to go back with a group of old toppies and our own music.

There was a lot of skin and bare breasts but no public snogging. All the principles of Afrikaburn were upheld. I didn’t see anyone drunk or disorderly, though a lot were very heavily stoned.

I met a guy from San Fransisco, part of a group of a dozen who built the lighthouses and teamed up with some Swiss who had a disco. He enthused about Afrikaburn, said you couldn’t do nearly as much at Burning Man. It is much too regulated.

The burns started slowly, then spread very rapidly, then collapsed and lay burning for a long time. The heat was intense.

My back hurt a lot and I had to sit down half the time.

One of the principles of Afrikaburn is that there is no money. You can’t buy or sell anything (Except ice). Camps provide services: Drinks, coffee, showers, counseling, music, acrobatics, fancy dress, food, healing, postal services, vehicle repairs, games, demonstrations, art, massage, movies, tennis, treasure hunts, body painting, pillow fights and many more activities.

The 11 principals of Afrikaburn are: Communal effort, participation, civic responsibility, immediacy, deco modification, gifting, leaving no trace, radical inclusion, radical self reliance, radical self expression, each one teach one. There is a guide book explaining everything.

The concept started in a USA desert, which grew annually. It is called “Burning Man”. Now there are burns in many countries worldwide.

Other News:

Yesterday I got involved in penguin housing. I have a certificate which I got many years ago, to show that I have property on Dyer Island. The property is a fiberglass penguin nesting house. Before the discovery of guano on our offshore islands, penguins used to burrow into it to nest. When it was discovered that guano is an excellent fertilizer, the old wooden ships used to come to the islands and load up with guano. They used to fight over it. The guano in the bottom of a ships hold used to get wet and generate methane gas. If someone went down there into the pitch dark, carrying a lantern, the methane would explode and blow the ship to smithereens. Christine Jacobsohn drew my attention to an article which claimed that the bags of guano had to be kept out of the damp recesses of the ships, and were therefore marked “SHIT” for stow high in transit.

Now back to penguin houses. I want to make them out of Keraforce. The problem with the fiberglass ones was that they overheated. If you have a soft spot for penguins you can buy them a house. My dream of making thousands of Keraforce houses may soon become reality!

Best Regards,


Dear Readers,

I had hoped my last newsletter about arterial roads would get you thinking and get some response. I guess you all think I am mad. For those who are not yet quite convinced I am mad, here follows an even more deranged idea!

Now what about our public transport?   In Europe they have buses, trams, trains, express trains, underground trains, aeroplanes and taxis.   At a transport hub such as large railway stations and airports, all of these facilities converge.   You do not need to own a car, at all.   In South Africa we have…………...virtually nothing.   The Gautrain would work well in Europe, because it would connect with a plethora of complementary systems.   Here we have to create its own bus service to try to get it feasible.   To fix our public transport system would be an enormous task.   The rot set in when we abandoned our trams, which an old toppie like me can scarcely remember.   Let us not try to copy the first world, but face the realities of our situation and adapt to them.   Gauteng has a long axis from Springs to Randfontein.   Fortuitously it just so happens that we have below us a wide, gently sloping cavity which was formerly gold mines.   It extends all the way from Springs to Randfontein.   This would cost trillions to dig, but it happens to be there already.   Now since it is so wide, we could put everything except aeroplanes down there.   We could have separate roads for bicycles, motorcycles, cars, taxis, buses, trucks and trains.  What absolute bliss!!!

It wouldn’t get all the traffic off Jo’burg’s streets.   So let’s think about that.   We have basically cars and taxis.   How can we get them moving efficiently?   I propose a ring rail.   This is very wide railway line with very wide flatbed carriages.   You drive your car or taxi to the siding, select your destination, and follow the signs to your flatbed railcar.   Pay at the toll point, drive onto your flatbed.  After 5 minutes it engages with a cable which pulls it from the siding onto the mainline.   There it engages with the high speed cable and goes non-stop to your chosen siding.   It stops and you drive off and continue what’s left of your journey.   I reckon this would cut the average commuter’s travel time in half.   There is no locomotive, no exhaust emissions, and just some big electric winches.   No broken robots, no stress, no road rage.  You pass the short time chatting to fellow commuters who share your destination and time slot.

PRODUCT FEATURE – Detonator Coolers

My colleague Clive Woodford involved me in a project for an explosives manufacturer.  He was asked to make detonator coolers to prevent premature explosions in hot blast holes.  His solution was too expensive.   I did a lot of basic R& D and eventually solved the problem.  Our goal was to keep the detonator below 137°C for half an hour with the temperature at 1000°C in the hole.

Sometimes coal seams ignite underground, and smoulder very slowly because it takes very long for oxygen to get down there.    If you drill blast holes into such a seam, you suddenly let fresh air in and the temperature goes screaming up to 1000°C.   Then they put a detonator down, and pump dynamite down the hole.   The detonator overheats and explodes when it reaches about 137°C.  If you happen to be pumping dynamite down the hole at the time, the explosion goes up the pipe to the tanker and wipes out everything in the vicinity.  I devised a super insulation capsule to delay the heat transfer.

Wide ranges of porous insulating ceramics were tested.   Those which started melting at 1000°C were eliminated and those which exploded when placed in a furnace at 1000°C were eliminated.   A temperature calibration method was devised to indicate above or below 137°C.

Capsules with 9mm thick walls were placed in a furnace  at 1000°C and failed to keep the interior below 137°C for long enough.   Increasing the thickness of the walls would solve the problem, but the capsule has to fit down the drill hole.

A method of dissipating the heat was needed.

The solution will be called “endothermic thermal dissipation”.   The heat is consumed in an endothermic process.

An insulation material with good strength, very high porosity and ample permeability was selected.   The best was Keramicalia’s Kerafire.    A capsule cover was made from this material.   It was fully impregnated with water, and then frozen.    When the capsule is placed in a furnace at 1000°C the temperature stays near 0°C until the ice has melted.   After that the heat is consumed at 1 joule per gram for every degree C until the temperature reaches 100°C.   The temperature stays close to 100°C until all the water has been boiled off as steam.   Only then can the heat start to find its way through the ceramic.

A wall thickness of 9mm kept the interior below 137°C for 20 minutes.   One would expect the time to increase in proportion to the wall thickness.  

Endothermic thermal dissipation can be taken further by addition of solids in the ceramic structure which decompose endothermically.   It can then be taken still further by placing “dry ice”; frozen carbon dioxide inside the interior of the capsule.


Nearly all chemical reactions are associated with either heat absorption (endothermic) or heat release (exothermic).

Sometimes we use endothermic reactions to stop heat from travelling.  Phase changes also involve heat absorption or release.  Ice melts at 0°C.  It remains at 0°C, absorbing heat, until all the ice has turned to water.  Then the water absorbs 1 joule per gram per °C as it heats up to 100°C. Then it remains at 100°C (at sea level) until it has all turned to steam.  The most effective way to raise your swimming pools temperature is to cover it with transparent plastic, thereby stopping the heat loss through evaporation.

Insulation is effective as long as heat is extracted at the far end.  If you completely enclose something in insulation and place it in a furnace, it will reach the temperature of the furnace.  The insulation will only delay the heat flow.  Sometimes data loggers are mounted under kiln cars to monitor temperatures as they pass through a tunnel kiln.  The ambient temperature under the kiln car is too high for the electronics to work.  Since the cycle is several days, insulation alone cannot keep the electronic box cool. Here we have to use endothermic reactions.  Three types are used; an ice box enclosing the electronics, a water box, or a salt which absorbs a lot of heat to melt.

A client had a problem with a data logger.  I explained the endothermic principle.  When I arrived on site, I found the data logger encased in a steel bath.  One of the staff said “Oh yes, now I remember; we used to fill that thing with water.”

Many endothermic reactions are associated with the release of gas, most commonly steam.  Useful ones are gypsum → calcium sulphate hemihydrates (128°C) → anhydrite (163°C)

Aluminium trihydrate → aluminium oxide + H₂O at 300°C

Calcium Aluminate hydrates → calcium aluminates at 400°C

Clay → metakaolin at 600°C

Calcium carbonate °→ CaO + CO₂ at 825°C

Magnesium Carbonate → MgO + CO₂ at 900°C

When firing a ceramic body, these reactions must be accommodated.  Firing must be slowed down at the appropriate temperatures so that gases can escape without the pressure exceeding the tensile strength of the ceramic and causing an explosion.  Such explosions are quite violent.  I have destroyed a kiln at 600°C with a clay rich refractory; it blew the sides right off.  I also blew up a very dense 2.5ton refractory launder at 400°C, 40 hours into its drying cycle.  It destroyed the dryer, and bent the bogey, made of railway lines, to the floor.  The cops came to investigate the explosion, and it took me hours to convince them it was only a steam explosion.

Endothermic reactions are used in many fireproofing applications.

Have a great 2016!

Best regards,

Dave and staff.


It’s been a long time since I last wrote.   My new IT lady Marelize has been on my case, so here goes my blog;

Imagine if all roads were one-way.   There has never been a circumstance where cars come hurtling towards each other at a combined speed of 240km/hour, and then miss each other by about 2 metres.   Now imagine some bright spark says “Hey, I’ve got a great idea!   Let’s build roads adjacent to each other running in opposite directions, it will save a few bob on construction.”  Apart from the extreme danger, several other reasons will soon be forwarded why it is a daft idea.   Firstly, how do you know which side goes which direction?   “Oh well, we could all keep to the left.”   What about night time, you’d have headlights shining in your eyes.   If you wanted to turn left you’d have to cross the path of the oncoming traffic.   “Oh well, we could put up a sign so everybody has to stop there, then the first to arrive proceeds first.”   What about where roads cross?   “Oh well, we could make electromechanical devices to signal which cars can go and which must stop.”

Actually, the two way road is a bloody daft idea, and nobody would give such a proposal any consideration at all if it was proposed in a society which had only one way roads.   It is strange and incongruous that we still have this daft system in our modern safety conscious society.

I propose a system of one way arterial routes.   The system works as follows:   Routes are chosen for one way traffic.   You can join an arterial route from either side, but via a slipway, with a barrier to prevent you from turning the wrong way into it or crossing it.   If you want to cross it, you have to join it at one slipway, work your way across the lanes and leave at a slipway on the other side.   Now think about it; on an arterial route, nobody crosses your path, nobody travels in the opposite direction, no piece of tarmac is traversed in different directions.  Presto!  We don’t need stop streets, we don’t need traffic lights!   The traffic keeps flowing like on a freeway.   From the moment you access the arterial route to the moment you leave it, you keep on moving.

So what’s the difference between my arterial routes and a freeway, apart from the convenience of having a gazillion on ramps and off ramps?   Actually freeways are also daft.   They are built with lanes in opposite directions next to each other.   Instead of stop streets and robots we build hideously expensive bridges and flyovers.   If we built them in one direction, well separated from each other, we could have the convenience of my arterial routes, i.e. a gazillion on and off ramps, on both sides!

If this does not make sense to you, read it again.   Yes, it is too good to be true.   Pity it seems like it will never happen.

Product Feature;

Fireproof Paint.

We manufacture quite a range of paints these days.   They are mostly inorganic paints with rare and obscure functions.    One of them has good market potential.   That is our Fireproof Paint.   It is thermally insulating, being composed of hollow ceramic microballoons.   It is much harder than normal organic paints.   Most of all, it is an excellent oxygen barrier.   It is chemically setting and will not wash off if it rains on it 2 hours after painting.   It is quite amenable to colouring with oxides.   We make a yellow for new thatch and black for old thatch.  Doesn’t matter what you current thatch is.   Mostly it is used to protect wood, chipboard, OSB etc., but it even works on cardboard!   To demonstrate it we paint onto a piece of cardboard, show how it protects, then burn the cardboard away from the back, leaving only the layer of paint!   See………………………………….

Technical Feature;

Houses and heating.

Just a few random thoughts and observations.   Have you ever noticed when on a ladder inside, how much hotter the air is near the ceiling in summer?   Sometimes people install fans and complain that they don’t work.   This can be because the fans push down this hot air which got there by convection.   Apart from convection, I guess everyone knows how hot it gets inside your roof.   You can put insulation on top of your ceiling, but a whirlybird will remove the heat effectively.   Best is our Keraforce roof panels, which meet the most stringent insulation requirements.   They are so light and strong that you dispense with trusses.   You can dispense with the ceiling as well if you don’t mind seeing the wires for your lighting.

I have had potters, heat treaters etc. asking advice on how to remove their heat.   More often than not, it turns out the heat is largely radiating from their steel roofs.   This is easily tested.   Take a large board and hold it over your head.   If the heat instantly disappears, it is all radiant heat from the roof.   There are several remedies.   A reflective paint on top gives slight relief.   “Insulating” paints are a myth.   Sisalation under the roof works, expanded polystyrene is best of all, because it keeps the cold out in winter.   Keraforce on top works very well.   It was used originally to repair corrosion damage or leaks, but was found to have a huge effect on stabilizing the temperature.   Kiln fumes destroy galvanized roofs.   Keraforce on top of corrugated or IBR forms a new roof even after the steel has totally disintegrated and fallen down.

Heaters work by radiation, convection or conduction or a combination.   Air heaters with fans work, but the result comes slowly.   Radiant heaters give instant relief.   Underfloor heaters use all 3 mechanisms.   Thermal mass plays a large role in heating.   A good stone castle is virtually impossible to heat, though radiant heaters will give relief without having an appreciable effect on the wall temperature.   I built an ultralow thermal mass house out of polystyrene, with excellent thermal insulation.   I built a fireplace in it and guess what?   It heats up so fast that you soon want to extinguish the fire!

I made a monster heater out of Pizza Oven Floor Mix, our super high thermal mass material.   It had a 2,4 kilowatt element and weighed about 30 kg.   It turned out you must switch it on when you come home, then switch it off when you go to bed, and it is still warm in the morning.

What household heater works on conduction?   Bet most of you are stumped here.   Your electric blanket!

Keep warm ‘till the next letter.

Best regards,

Dave Onderstall and staff.


Dear friends,

We lost a lot of business last year because our Telkom land line was broken about half of the year.  I heard that Telkom has so many broken lines that the technicians have to steal someone else’s line to repair yours. That person reports their line broken so 6 weeks later they steal another working line from elsewhere. We now have a wireless Premicell no. as our main contact.

Our numbers are:

Telkom: 011 412 3261 usually broken or inaudible.

Premicell: 074 587 2728

Fax: 011 692 1232

Accounts: 011 764 2139

Payments: 011 660 1606 Judy

Technical: 082 808 4757 Dave

Admin: 083 264 2955 Iris

Production: 079 622 3279 William

Drivers: 076 293 5967 Johnson, Solly 073 713 9564, and Alpheus 072 791 2841

Accounts: 083 258 6060 Myrtle

IT: 078 428 2307 Ellah

Maintenance: 071 440 1239 Solly

Web site www.keramicalia.co.za

Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Accounts: This email address is being protected from spambots. You need JavaScript enabled to view it.    myrtle

                 This email address is being protected from spambots. You need JavaScript enabled to view it.

Payments:  This email address is being protected from spambots. You need JavaScript enabled to view it.

Dave: This email address is being protected from spambots. You need JavaScript enabled to view it.

Post: P.O. Box 69 Paardekraal 1752

Factory: Corner Steyr & Alfa Str. Aureus, Randfontein.

We have been on the same premises for 23years now

We now have 375 products on our price list, and 182 data sheets on our web site and 940 precasting moulds. We have done over 1000 development projects and have 350 running metres of shelving with developed samples of materials.

I think we have captured about 1% of our local potential market. We still rely on everybody in the refractories industry to distribute our products, we still have no salesman. We still refrain from manufacturing products already manufactured in SA, but we do buy and sell these.

Our range of technologies is now so wide that we can supply your exact needs or modify a developed product within hours or days to suit your application. Factory 5 is full of our fast moving products and can be dispatched usually within 20minutes of your order.

We have a new phone number it is 074 587 2728.

Our Telkom line is still down, has been since 1 August. Every time we phone them they place it on "higher priority", it must on higher priority than the fire brigade's line by now, but that hasn't helped at all. The good news is our new line has nothing to do with Telkom!  One step closer to Utopia.

Sorel Cements

One day about 30 years Dave Thomas showed me a Sorel cement polishing wheel, not knowing yet what it was made from.   We were both enthralled by its hardness density and lustre.   I tried to replicate it with my Versimould technology but got nowhere near it.

It turned out to be Sorel cement; magnesium oxychloride. Over the past 30 years I have been involved in 26 developments projects using Sorel cement and have made some amazing products.

The story of my first Corcolium project is interesting.    Cornelia de Villiers bought a flat in Killarney with corcoleum floors, but it had been removed in the bedroom because it get wet once.  Corcoleum is cork chips bonded with Sorel.   She wanted to replace it.    Of course this is one of those “counter economical” projects, but she wanted it so badly that she came and helped me in the lab.   She named one mix “puppy puke”.  I didn’t like any of them, but she was happy with one, so I sold her the mix.    She mixed it in a 20litre nappy bucket.    It got hot,  it set hard, it started steaming and then it started exploding!   She sent her gardener off into the street with it and he hid behind a dustbin while it continued to spall explosively from the steam!    A piece of it was very exciting; a hard strong lightweight foam! Possibly the best strength to density ratio I have ever seen.    I tried to reproduce it in the lab but failed. I phoned her a few times with questions to no avail.   Of course I was being stupid, it wasn’t a detail of the formulation it was a question of scale.  I only realized later on the mine consolidation problem, when I had buckets of Sorel exploding.   The potential is there to make awesome foamed boards confined under pressure.

The mine consolidation project was interesting in that we used a Sorel cement so liquid that it ran almost like water through a pinhole in a plastic bag.  The mix was poured into a bucket full of rocks where it set hard.  Same as “infilcast” Technology.

The next project was for lightweight floorboards for containers.  Dov Calo rented my facility and we learned a lot about scaling up the mixes and the exothermic reaction running out of control.

Then most of the work was concentrated on abrasives and polishing wheels, blocks, segments and cubes.   We made a sample of a small glass beveling wheel for LTL abrasives.   After about a year I asked if there was any feedback.   They asked the rep to check it out.   He came back reporting “total disaster the damn thing is still working”.    Then there was this guy who wanted “magnesite boards “.   These are one of the most stunning of Chinese imports.    I dived into it with passion, called him to come and look when I was 90% there.    It turned out he was not willing to pay me for the technology nor was he willing to buy the raw materials from me.   So once again my R&D expenses were rewardless, and once again a stunning technology was left on the shelf.   This stuff STAYS INTACT after the cold crushing test.     I’m sure the mines could use it somewhere.

Made lots of other stuff and then got an enquiry for lightweight rollers.   A company was using long  steel rollers, which weighed 200kg and cost a lot.   I guessed we could get the same rigidity at a third of the weight and a third of the cost.   I showed the customer how hard Sorel cement is and I showed him my lightest pourable material, he said “why don’t you just mix the two together” instead of puking, I politely said I would try it. The resulting mix was interesting in that it ran like water.   The mind blowing part was that it set very hard!   I named it Reinite in his honor.    Reinite proved to be very compatible with reinforcing, a brilliant substitute for polyester resin in fiberglass and so clean and pleasant to work with.   The composite technology is now called “Keraforce” it was tested in a vast range of fibres and the unwoven fabrics proved to be the best because they cannot be pulled diagonally.

We started making all sorts of things from Keraforce mainly using expanded polystyrene cores.   When my staff saw me making something looking suspiciously like a ladder, one of them asked “Is that a polystyrene  ladder you are making?”   I replied in the affirmative and he shook his head, certain that I had now gone completely mad and said ” there is no way I will ever climb that ladder!”    The ladder turned out great in that it is so rigid it does not wobble at all, and feels really safe.   I even made an extension for it.    We are still experimenting with lighter ladders.

We devised a system of making large pots which nest inside each other like Russian dolls.   Ilana potteries were falling apart and Christine asked for help.    I fixed all her tables and benches with Keraforce, I fixed her kiln cladding with Keraforce. I fixed her roof and gutters with Keraforce, even her garage door.   Problem was, the weight of the garage door was now too great for the counter weights.   Guess what I used to enlarge them?   Ilana’s roof was extended and modified with Keraforce but it was a bit heavy.   We needed a lightweight system.   Eventually we figured out a system of very strong, insulating boards using polystyrene cores.

Solly built a shack in factory 3, which Iris dubbed a “kerakhaya.”   Along came Paul Olver and Liezl and soon we were brainstorming shack production.   Some lateral thinking produced a shack which can be assembled in minutes.   Liezl has registered a company for us under the name Biohabitat.

Hello there,

I feel my writers itch flaring up.   I come from a line of writers and journalists.  I feel this is going to be a long story.   Gerhard Louwrens and I have just spent a fascinating morning with Peter Ringdahl.   He explained in great depth and clarity the history and technology of synthetic diamond manufacture, illustrated with samples.   His samples of synthetic diamonds look really stunning under his microscope.   Not high purity, but each one with every crystal face perfectly formed.

But this story is not about the diamonds, it is the story about my involvement with pyrophyllite, a natural mineral without which synthetic diamonds cannot be manufactured.   I have to leave out a lot of it for political reasons.   One of my first involvements with pyrophyllite was with a synthetic diamond manufacturer.   They milled the pyrophyllite, screened out the desired size fraction and threw the fine powder away in 110 litre drums.   At the time, Keramicalia was a minerals by-product trading operation.   (I was under a restraint of trade from my former refractories employer.)   I offered them a better deal: I would dispose of it at no charge, but no only that; I would supply the drums at my own cost.   They said they would think about it.   After 2 weeks they decided they would rather carry on throwing it away at their own expense.

I was approached by a consulting geologist offering me pyrophyllite from the Wonderstone deposit in Ottosdal.   I collected samples and found that the variation was too erratic.   One end of a large rock would yield a perfect fired sample and a piece taken from the other end would disintegrate on firing.   Pyrophyllite is a phyllosilicate, related to clays, with a texture and mechanical properties similar talc.   Talc, also called steatite, is the soapstone from which ornaments are made in Zimbabwe and Swaziland.   The Ottosdal  pyrophyllite is grey to black in colour, and if you like sculpture, there are some enormous and intricate and almost unbelievable examples at Assore’s head office in Fricker street.   Assore owns Wonderstone, the company mining the largest of the Ottosdal pyrophyllite deposits.   The name Wonderstone was given to the Ottosdal pyrophyllite way back.   I have a geological survey report on the deposit issued in 1937.   (It cost 6 pence.)    The deposit was then a mountain, now the mine is below ground.  Wonderstone was machined on lathes etc. into intricate parts and then fired into hard ceramic components.   Today most of it is milled fine, calcined, bonded with sodium silicate, pressed into shape and then fired.

At a foundries exhibition in Dusseldorf I saw a remarkable refractory brick.   It was absolutely solid and smooth, looked almost like plastic.   Sang-yu refractories invited me to visit their plant in China, and I did so some years later while on a pot shopping with Adriaan Turgel.

Dear friends,

Sorry I have been quiet for so long. We are still here in the same place for the last 23 years.   I still mess around in the lab all day instead of trying to sell my products.   I still rely on you my friends and colleagues to send me business. My web sites are bringing in most of the business. The old one, Keramicalia.com is being replaced by a greatly extended one, www.keramicalia.co.za.   The problem with the web site is that it brings in all sorts of obscure enquiries.  The problem with me is I need to solve all the problems.  Having solved them I sometimes forget to tell the customer! I lose interest in them totally once they are solved. Most of them have no commercial value anyway.

In order to try to make a living out of this commercial disaster, I have had to change my way of doing business.  What I now try to do is charge for the R&D rather than sell material.  I negotiate a clearly defined, measurable goal with the customer and we set a price. He gives me an order and if I achieve the goal, he buys the technology.

In difficult projects, we set intermediate goals with prices.

Often the projects are beyond the boundaries of my experience. I have decided to bring in experts from other fields.  I found that retired technologists are all very keen to take up new challenges.  I have found over the years that some of the best technologies emerge when people from widely differing technical backgrounds get together on a problem.  Why not get all the retired top technologists together and work on difficult projects?

I have started putting together a consortium of brain power and I have already got a formidable team of experts, companies, laboratories and plants on board.  Already I offer a huge infrastructure and expertise in the metallurgical field.

I am advertising in the Engineering News on the 10th August for recruits in all technical fields.  The consortium is called “Keramicalia Research and Development” I suspect I will inundate with recruits.

I would like all my readers and colleagues to join in this venture. Just send me a CV, photo of yourself, some descriptions and photo of achievements, hobbies, interests. I would like to, with permission, out you on the web site.


I see one of the greatest problems of the corporate world as being their buying systems.  I call it "Passive buying".   Procurement is centralised in a department in which the staff have no specialised knowledge of the products.  The technical guy who needs a product, requisitions it.  It goes out on tender and gets bought from the cheapest supplier or the one who manages to buck the system.  The product purchased may have little in common with the requisitioned item.  We all know that money changes hands under the table, but the responsibility for purchasing is so diffuse that  nobody can be pinpointed as guilty.

I have a large corporate company that has been buying a small item off me for many years.  I don't really want the business, I don't even manufacture the product, I just outsource it.  Then one day I had to tender for this business.  I sighed, doubled the price and tendered.  Mine was the only tender.  Then they lost my tender.  I said "that's fine, I don't want the business anyway."  This caused great consternation.  If I don't supply it, where will they get it?  I said I was sure they could get it for a quarter of the price in India, all they have to do is look for it.  Look for it?  What a concept!  They have never looked for anything before.  All they do is wait for people to come and beg them to buy their products.  Now I suddenly had this huge corporation begging me to sell them a product.  I was most amused.  I told them I reject their conditions of purchase, and if they want to buy from me they must pay up front.  This really cast a cat amongst the pigeons.  Five months later I was paid up front and I supplied the goods.

The suppliers who push their products are the ones who have little to offer.  The suppliers who do not push are the ones whose products are bought on their own virtue.

So how should purchasing be done?  Whoever needs the product should take full responsibility for it and buy it.  If it works he should get the credit and if not he must suffer the blame.  Under these circumstances corruption cannot thrive.

Open tenders are good, provided all suppliers get the enquiries.  It is a pity that no refractory consumers send enquiries to all the suppliers.  "Active buying" is where the customer goes out and looks for the appropriate product.  Unfortunately this only happens in small and medium companies.

Here's a neat tip; if you want to sell anything to the mines, just give your card to the guy who needs the product and tell him since the mine does not have an account with you, he must choose an agent himself to represent you.  Watch the miner smile!  Your business is in the bag, and at your price too!

We use the whole refractories industry as our distribution network.  If you are looking for anything novel or unusual, we can supply it for commission, or in blank packaging or in your bags or whatever suits you best.


Judy is doing well with her cancer; she is currently recuperating on a cruise ship where my daughter, Gina is the ship's nurse.

Keramicalia is developing new products faster than ever and we are having fun.

One new product is a ceramic to replace polyester resin in fibreglass.

Another is Marna's new moulding compound called Marmould.  It is a hot melt compound which melts at 50 degrees and takes up immense detail.  Our most spectacular success was a puff adder which Dave found dead on the road.  We made a mould with Marmould and cast it in silicone.  The scales ACTUALLY OVERLAP!!

See the photos on our web site www.keramicalia.com/moulding/marmould.

Dear Readers,

I believe that one of the most important things in business is taking responsibility for your own actions.  I am afraid to say that I see less and less of this happening.  One of the most infuriating things is broken promises. 

Today I find that corporations build sturdy firewalls to prevent customers contacting management.  Mercedes Benz is the most impressive I have encountered.  These guys are masters at keeping customers from complaining.  Judy bought a Merc. which soon showed up a factory defect.  It was "repaired" several times but the problem remained.  Judy got nowhere with Daimler Benz, so I volunteered to "show them", but I got nowhere.  You simply cannot contact the CEO.  Eventually I got his e-mail address by being abusive, sent him a serious complaint, with copies to motoring magazines, and still I got no response.   They actually do not care.  Then Christopher, who is at home in the corporate world said he would show us how to handle it.  He too failed to get any response.  Then I tried to get a ruling on how many times a factory fault must be "repaired" before the vehicle is withdrawn.  It was made very clear to me that no matter how many times they failed to fix it the vehicle would never be replaced.  I had to concede defeat, see my last e-mail.  All I can do now is tell new would be buyers of Mercedes that they should change their minds, because Mercedes doesn't care. 

We seem to have a huge variety of vehicles to choose from today.  Perhaps the way to choose is to make a short list and try to 'phone the CEO of the company.  If you can reach him, as a man on the street, then definitely buy that car. 

If you 'phone Keramicalia, you usually get the owner within seconds.  I try to follow Ellis Falkof's policy "We may discount our prices but we will never discount our service."  I always take back materials for full credit if they turn out to be inappropriate, faulty, or in some instances even beyond their shelf life.  That's taking full responsibility.  I pride myself on being on a sole trader, not a CC or company.  People say I am exposing myself to risk.  I simply have to be extremely careful then, don't I?  I stand by my products, so you can use them with confidence.  I will make anything you ask for except something "the same but cheaper".  Part of the price you pay at Keramicalia goes towards service, delivery, research and development, testing in new applications and operational help and training. 

Have you noticed how many disclaimers you see these days?  I have considered putting at the bottom of my data sheets "this information had better bloody well be right because Dave Onderstall stakes his reputation on it".


Bad news unfortunately, Judy has cancer.  She has multiple Myeloma which is incurable but treatable.  She is now in remission and planning to live her life even harder!

Marna Olivier has joined us to do research and development.  She seems to be enjoying it excessively, I can't get her to go home at 5.  Myrtle and Mieke have taken over the accounts dept. with great vigour and are busy fixing all the stuff I have been selling at a loss.  My friends may have to withdraw my nomination as worst businessman of the year.

We are making element cages for the pebble bed test plant.  They are conceivably the most stunning looking refractories ever manufactured.  They fall into the area between technical ceramics and refractories, an area in which Keramicalia has been active for many years, and I have still failed to come up with a name for  this class of materials.  These materials are usually free flowing slurries which set strippable in two hours, are cast into elastic moulds and can take up extreme detail and wall thicknesses as low as 2mm.  Their compositions are alumina, zircon, aluminosilicate and other.  Strengths are generally high, and the commonest firing temperature is 1250 deg. with 5 hours soak.  Back to the cages; Jay Lloyd designed the concept.  I told him it was way past the limits of refractories fabrication, but he proved me wrong.  Ernie Coomb did the first production.  Chris Koch discovered them, commissioned some fancy ones and then brought the Pebble bed guys to the party.  Their requirements were way beyond the run of the mill refractories tolerances, so I got Composite House to design and manufacture the moulds.  Their mould makes the space shuttle look primitive!  The end result is a most stunning product, accurate to 0,3% with unprecedented efficiency and reliability.  It recently struck me that this is the solution to Prof. Jeff Ferreira's problem of how to build a furnace to ship around the world without it arriving in a heap of IFB crumbs.  Watch this space!


1.  Jack Marshall has an invertor, 42..........  Any offers?

2.  Jack also brought a small kiln which I jazzed up.  It fires very fast and guzzles electricity. Any offers?

3.  I bought a Wacker vibrator motor at an auction, got home and saw it is a 42Volt job! Can anyone use it?  I want only 10% of its replacement value of R12000.

I want to get out of precasting and more into R & D.  Is anyone interested in taking over my moulds?  There are about 750 different shapes.


When I started Keramicalia I wanted it to become the place where all the interesting enquiries end up. After 20 years it has got there, and I am very happy, Keramicalia may be a commercial disaster, but we sure have a lot of fun. This is the way I wanted it.

My wife, Judy just looked over my shoulder and pointed out that my title is her saying. Yes she is the master of “Making it Happen.” She has a Range Guide troop, and one day she announced that we were all going to Switzerland for a skiing holiday.  The parents thought she had “lost it”; I personally thought she had finally bitten off more than she could chew, but sure enough she got us there. Eleven girls, my whole family and a few other parents. It was the most awesome holiday. Yes it was a lot of work, some inventive fundraising, but it was unwavering, focused effort for a couple of years, and nobody regretted it. If you focus on your goal you get there. You lose it when you take the line of least resistance.

We have brought up our children in this culture of making it happen. Gina is now a trauma nurse, working on a ship doing a world cruise. John is going to China in May to film driving a convoy through China, India, Pakistan the Middle East to Djibouti, Ethiopia, through Africa ending back in Northcliff. Christopher has just come back from the USA where he spent his varsity holiday working in a shop, then checking out Washington and New York with his earnings. Nikki is having a ball with her gap year at a school in Southampton. I am so proud of all of them.

One of my most irritating saying is “Why put off for tomorrow what you can just as easily do today?” I am not good at that one, but at least I try a bit to strive towards it.

So think about what YOU really want, not what society expects of you, and go for it NOW.



Kerasic is our alumina bonded silicon carbide material. The “sic” comes from SiC, the chemical abbreviation for Silicon carbide. The” Kera” is because I am not very imaginative and call most of the things I make Kerasomething or other. (None of my kids are Keraanthing) kerasic is a fine pourable material and lends itself to very complex and intricate castings. It is used mainly for thin walled castings, for example, sintering trays, thermocouple sheaths, elements sleeves lances and fluxing tubes, thin walled crucibles, furnaces muffles, heat radiators, element cages and distillation columns it is also extremely strong. The items above are all small sophisticated expensive pieces and the cost of the material; R45/kg is no problem.

Gideon Kriel of Gee Kay Industrial Ceramics was a pioneer in the use of Kerasic and made some remarkable items.   Hennie van der Bank of Quarlcor got rapid casting down to a fine art, and could turn around moulds in 20minutes!

Jay Lloyd of Fornax pioneered Kerasic as a die-casting material. He was casting items in a R10 000 steel die of 2 cavities. With Kerasic he made 24 spin casting moulds at a cost of R6 each. The high thermal conductivity of kersic is good for die casting, also the fine surface finish and thermal shock resistance. Jay then started making thin walled crucibles. Because of the high strength, they do not have to be as thick as graphite crucibles, so you get faster heat transfer. Jay’s sidekick, Peter has invented an ingenious machine for moulding and stripping them. The three wise men of the gold industry have been doing ground-breaking work on composite castings using strange bedfellows such as kerasic and cellular insulation materials, also Zirconiaflow and Kerabrade C and Keratab Ultrafine. They have  had  some magnificent results. Of course I always want to cut them up to see the interface. Some of them don’t work at all on paper, but work brilliantly in practice. Now they can have their cake and eat it, a single component can be pyroplastic at one end, strong in the middle and insulating at the end.

Currently the crowning glory of Kerasic is Jay’s Element Cages. These are the most intricate castings I have ever seen. When he conceived the idea I told him it was impossible. But as Gideon says, anything is impossible until someone has done it. Element cages are shaped like squirrel cage and hold elements in place while hardly impairing radiation, and with almost no thermal mass. Take an element cage, wind an element into it, wrap it with fibre blanket, clad it, insert a kerasic crucible, connect it to 220 volts and you can melt 2kg of aluminium in 20 minutes .   I have been working on a Kerasic pump for molten aluminium.  I had problems in some areas. I believed it would be impossible to machine Kerasic, but Danie Wilkins of the CSIR proved me wrong! He has made some components of unbelievable precision.

We have got the volume stability remarkably good, and we can now cast 2 metre rods at 19mm thick. We have one 4 metres long now, still in the mould. I need to build a kiln to fire it as it passes through vertically.

Technical Features;

Silicon Carbide

Silicon carbide is a remarkable material. Diamond is the hardest natural mineral, 10 on the Moh scale of hardness. And corundum comes second at 9.    ( That’s where the company “Moh 9 got its name.   Silicon carbide has a hardness of 9.5. It is therefore the first choice for abrasives, not being as expensive as Diamond.

The other superior it has is its cleavage. It breaks with sharp edges. I am having difficulty getting facts and figures for this article, because silicon carbide does not occur naturally, and is therefore not found in any of my mineral reference books. It is not likely to be found in nature, as its synthesis requires the equivalent of long standing bolts of lightning. *Silica and carbon are placed in a long pile and an enormous electrical current is run through it for days on end. The result is a fused but porous mass of large silicon carbide crystals. The electricity consumed would make even a submerged arc furnace operator cry. The lump gets sorted into green silicon carbide from the centre and black from the outside of the pile. Next the material gets crushed. In the process, the silicon carbide removes a lot of the metal content of the machinery! Now it gets screened these sharp particles are difficult to screen, and abrasive manufacturers always use single sized particles, so that there are gaps between the grains, otherwise grinding wheels would not work. This gives the producers a major headache, because they may have 20 customers wanting 50 to 60 mesh and nobody wanting 60 to 70 mesh. It all adds up to make silicon carbide rather expensive. For sub micron material I have paid as much as R80/kg. Silicon carbide has an enormously high thermal conductivity. Pure crystals have a conductivity of 84 Watts per metre Kelvin. The highest of common Refractories is magnesite, with a measly 4W/mK. Yet fused magnesia is used as the isolator in stove and kettle elements. Why not silicon carbide? Well it is also electrically conductive. This makes it suitable for globar elements. Wonderful things, but pricey. The other property of silicon carbide is its high surface tension. It is not easily wetted by liquids. This makes it difficult to formulate pourable refractories, but makes it perform superbly in molten metal contact situations.

*Frans Nyikos recently gave me a book on silicon carbide which records a few small natural occurrences


For sale 5 cubic metre kiln belongs to Grob ceramics, now retiring R100 000

I want second hand and scrap kilns to repair and sell

3 000 insulation bricks, 1400°C @ R20ea

Sorry this newsletter is such a mess, I want to put a place for you to unsubscribe but haven’t got that right yet.

Dear Readers,

This newsletter was written on 2.5. 1997!   Then my photocopier broke. Colin Coomer lent me his old machine.   We were both bidding on this machine at an auction, but I backed down.   Anyway, thanks, Colin.

As you can see we are now on e-mail and have a web site.   The web site, when it works, contains most of our data sheets.   You can download it or we can give you all our data sheets on a disc.

I have had a lifelong assosciation with the medical profession. My father was a doctor, my daughter is a nurse, my wife and my mother have both been medical receptionists and my mother in law is a matron. South Africans tend to regard doctors as omniscient and infallible beings. If a doctor lets on to a patient that he does not know everything and can possibly make a mistake, he will probably never see that patient again.   If he keeps up the image of being infallible, he may feel terribly guilty about it, but at least he will stay in business. 

 So what can you do about it?   My advice is this;   When you meet your doctor, tell him that you don't expect him to diagnose your ailment.   I tell my doctor that I don't know what's wrong with my body even though I live in it, so I really can't expect him to find the problem. I would, however, gladly pay him to listen to my layman's description of what I feel in the hope that he may have some suggestions.   You will probably see your doctor visibly relax, and I am sure he will be totally honest with you.  

Another thing I believe about medicine is that half of healing is psychological. Sangomas successfully kill people just by convincing them they are going to die.   Conversely, people have been seen to survive extreme injuries if they have a strong will to live.   I believe my wife saved my life when I was dying from malaria and failed to respond to treatment.   She stayed at my side and fuelled my will to live. She even invented stories about cute things my daughter had done. My running friend Mervyn Niland has some fascinating stories about mind power.   I went to one of his seminars recently, and he got us all, everyone in the whole group, walking over red hot coals!   Nobody even felt any heat on their feet or showed any sign of burning.   As a refractories technologist I find that fascinating.   Go on, try it, Mervyn's number is 083 286 1936.


Product Feature - KERAPUMP

Since I first joined the Ceramic Society, Dr Richard Kruger was dead keen on cenospheres.   He introduced me to them, and opened up a whole new world of possibilities.   After many years of toil and maneuvering, Richard realised a dream and commercially produced cenospheres.   We worked together closely and Richard gave me immense support to create a whole new generation of refractories.  

Cenospheres are tiny hollow ceramic spheres which impart amazing properties.   They flow almost like water and impart brilliant thermal insulation properties.   I call the new generation of refractories "Cellular Insulation".   The materials made from cenospheres appear to be solid, but are full of microscopic sealed cavities.   Many readers will have seen the demonstration or the advertisements of me holding in my bare hands a crucible with 2000øC molten steel in it.

Kerapump is a series of pourable or injectable refractories.   Kerapump 1 stood around in the lab for a while.   Colin Coomer asked me if I could meet the stringent spec. for an insulation material for Mossgas.   I said I think I have just the right thing.   I had tests done on Kerapump 1 and it exceeded the strength requirements so far that Mosgas rejected it!  

Iscor Newcastle were pumping an imported insulation foam on their hot blast stoves on hot spots.   They had to repeat the procedure every few months on exactly the same spots.   They agreed to try Kerapump 1, and it worked permanently. Some years later Mike Kuys 'phoned me at 2am on a Monday morning.   A section of the roof of the hot blast stove had fallen in, just after they had spent R20million on relining the blast furnace. If they did not get the stove going soon, the whole blast furnace would solidify and have to be rebuilt.  Kerapump was the only hope.  Everyone pitched in to help.   We even had two ex bank managers driving bakkies up and down from Newcastle.   Four days later the stove was back on line.  

We didn't have a party, we all went off to sleep for a long time. Some months later Mike Kuys 'phoned again.   Slight problem; somebody pumped Kerapump into the compensators, a sort of expansion bellows, and they jammed solid as a rock. Could I make something compressible?  

And so Kerapump 2 was born.

Billy Wolmarans and I repaired cracks behind the buckstays at Vanderbijl's coke ovens.   The cracks were totally inaccessible behind the buckstays, we we plugged up all the openings around the buckstays with Versimould Plug, leaving a pipe protruding from the gap.   Into this we pumped Kerapump 1.   It was most dramatic.   Smoke and flames were billowing out from the roof over the regenerators, and about thirty seconds after we started pumping, the smoke and flames would suddenly vanish.   Working conditions were apallingly hot.   Everything got hot.

The floor was so hot that at times when we picked up plastic bags of Kerapump the bottom of the bag stayed stuck on the floor.   Kerapump kept setting in the pump because the water was too hot.   Back to the lab.    

Kerapump 3 was invented; more fluid, with a longer setting time, or rather more of a heat set.   Now it can travel far around a furnace shell, then penetrate cracks and set on its way to the hot face. Martin le Roux discovered Kerapump 3 for glass bending moulds.  Previously glass benders had to make clay moulds, prefire them to ñ1100øC and then bend their glass over them.   They used to break after about three bendings.   Now they can make them with Kerapump 3, fire to 400øC or use them straight away.   They seem to last indefinitely.   This was such a revolution in Martin's business that he spread the news far and wide.   He couldn't do enough for me.   He gave me his whole pipe collection, including beautiful hand-carved meerschaum pipes.

I find Kerapump 3 ideal for modelling, because it takes up very fine detail, is volume stable and easily workable to a fine finish, due to its very fine homogeneous microstucture.

Kerapump 4 is still slower setting and softer.   Kerapump 5 is lower density, designed to replace Marinite, an asbestos based material used in the aluminium industry.   We made some superb Marinite replacement parts for a customer, but he was reluctant to change.   It turned out that if he changed, four of his colleagues would be out of their full-time jobs machining Marinite!   Our latest development is floats for continuous casting of aluminium.   Gideon Kriel is doing the development.   The floats control the flow in the same way as a needle and seat mechanism in a car's carburettor.   Gideon's samples look stunning compared to the calcium silicate components which have replaced Marinite.

Kerapump 6 is a dense pumpable material with a high zirconia content which has been used in blast furnace repairs.

Kerapump 7 has largely replaced Kerapump 3.   It has a very high tolerance for "abuse" on site, and can be used over a wide range of water contents.   It is very fine and we make thin walled insulating coffee mugs from it just to demonstrate how good it is.

Technical feature


Ladles are very large refractory lined pots for transporting molten metals.   In steel plants they carry in the region of 70 tons of molten steel.   They are mostly transported by overhead cranes.   Imagine one of them springing a leak!   Well, it happens.   It happens frequently.  

Every time it happens, there is an investigation, and I am always very sceptical of the conclusions.   The conclusions always strike me as being the only possible theoretical explanation anybody could come up with, even though it seems rather far fetched.  

If molten steel finds a crack leading to the steel shell of a ladle, it will run through and freeze almost instantly.   The only breakout explanations that hold any water are those in which the steel continues to flow against the shell.  This necessitates a cavity or labyrinth of cracks in contact with the shell. Mike Moore of Richards Bay Minerals discovered that when he increased the capacity of his ladles, the pressure against the shell increased, as evidenced by the insulation being crushed.   This had me puzzled for some time.   The explanation is as follows;   The total outward movement of the refractory lining is determined by the highest expansion.   The highest expansion is on the hot face.   The larger the diameter of the hot face, the greater the movement outwards of the lining.   The hot face of the bricks on the working face expands and the bricks push each other away.   The colder bricks are in turn pushed outwards, but they do not expand as much.   It follows that the colder bricks are no longer in contact with each other, but are separated by small gaps.  

The chances of steel getting into this labyrinth of gaps is small, but it does happen.   Note that the pressure forcing it in is enormous.   2" metres of molten steel has a pressure equal to 20 metres of water.  

From my explanation, it follows that you can build a ladle lining absolutely perfectly free of cavities, but once you heat the hot face, it will contain a labyrinth of gaps in contact with the shell.   The solution is dead easy.   As soon as the ladle is hot for the first time, pump some Kerapump 3 through nipples in the shell, and it will fill all the gaps.   No gaps in contact with the shell means no possibility of a breakout.   There we have the solution to saving countless lives worldwide and millions of rands of equipment.   I wonder if anyone will ever listen?   If I were a mason building ladles I would certainly latch onto an explanation of how my perfectly solid linings can leak.   Would't you?

Our business still revolves mainly around solving problems. We get far more enquiries nowadays than we can handle. We try to attend to them according the following priories.

1.  Firm orders

2.  Established customers

3.  Cash customers

4.  Those who pester us the most.

5.  Those problems which are technically the most interesting.

Usually we can supply materials off the shelf that are more appropriate than anything made by the bulk manufacturers. We are getting the bulk of our sales today through agents, other refractories manufacturers, suppliers and installers.   We like it that way, as we do not have our own salesman.


My landlord, Hennie Maree, has a 35 cubic foot pottery kiln to sell. It opens both sides, and has never been over fired.   Tel. 692 1657.

I want to praise our local truck drivers.   I find them considerate and friendly.   Their practice of pulling over onto the verge of the road to let cars pass is not a legal requirement, in fact I understand it is illegal.   Of course there are some nasty ones and some idiots, but I think the standard is generally high.   I hear so many people complaining about trucks in the fast lanes of highways.   They are merely obeying the overhead lane markings.   Sure it is annoying that they do not keep to the left lane, but look at the overhead signs next time you get annoyed, and you will see that the truck drivers are merely obeying the signs.   It is the idiots who planned the signs who are causing the obstruction, not the truck drivers.  

We have all seen the extent to which truck drivers are harassed by traffic officers, yet they put up with it.   It makes me wonder how badly the cops harass township dwellers to earn such hatred. Jerry once had a puncture on our old Toyota Stout 1« tonner on the way to Rustenburg with a full load.   Believe me it is a hell of a job changing one of those tyres with a full load. A traffic cop pulled over, and instead of offering help, gave Jerry a ticket because the tyre he was removing was now damaged. I had a flat on the highway with that same old Stout once, and found the spare was flat too.   I had no difficulty getting to a garage and back with my two gynormous tyres, thanks to, you guessed it; truck drivers.


Kurt is back from Germany. We had a record turnover in his absence.  Perhaps he should go more often! John Onderstall has just won the Art in Magic junior championship in Gauteng.   He is available at R30/show for kid's parties.   Tel 660 1606

The Onderstalls have moved to 289 Jorissen str., Krugersdorp. The photocopier has just acquired a new drum, and it apologises for the poor quality of the last newsletter. Karbochem has just cancelled a large order for Multimould industrial gaskets.   The reason;  When they opened the sulphur tank for the reline, they found the old Multimould gaskets still fit for re-use. Previously no gaskets had ever lasted one campaign successfully.

Readers' contributions                                                 

We have a few letters from prison from irate readers, the rest of you keep up the fight against the evil toll-lords. Doug says he doesn't pay toll at all anymore, just drives through, and invites us all to join him.   John Weston says he used to wait patiently in toll queues, but now that he is aware of how unneccessary they are, he finds it irritating.   Sorry, John.

Anyone want a second-hand Carbolite kiln? Make an offer.

Frik van der Berg is selling his bus, and wants R45 000.

Product feature  


Versimould is our product range of "Cold setting phosphates".  Phosphate bonded materials are normally heat-setting.   "Cold-setting"means that they set by themselves, but it is a bit confusing because they can get very hot from their exothermic setting reactions.

They set rather rapidly.   We have achieved 20 MPa in 20 minutes! The strength of Versimould products can be rather deceptive.   Some of them can be thrown onto concrete without breaking.   They give the impression of being extremely strong, but if you measure their cold crushing strength, they give values around 20MPa.   Some of them do not break at all in the cold crushing test; they simply carry on deforming. What makes them different from normal ceramics and refractories, is the fact that they are not brittle.   You can hit them with a hammer, and leave a slight dent instead of shattering them.

Another valuable characteristic is the fact that they are impermeable.  One of applications for this property is casings for porous plugs. "Porous plugs" or bubbling plugs are refractory cones built into the bottom of ladles or furnaces to blow gases into molten metal.  Traditionally they have metal casings, and it is notoriously difficult to get a gas-tight seal between the "can" and the refractory.   In induction furnaces, a steel can cannot be used, as it is within the induction field of the furnace and would melt.   We make special bubbling plugs with a Versimould casing for this application.

Versimould is supplied as a powder plus liquid.   In many applications it is recomended to refrigerate the liquid before mixing.   In some cases this is absolutely essential.   One such case is repair of rotary kilns.   Rotary kilns have to keep turning, otherwise the top gets too hot and the shell buckles.   Repairing them is a major operation involving a lengthy shutdown.   With Versimould, a small patch can be repaired from the outside by injection.   The kiln is stopped for a few minutes with the hot spot on top.   A nipple is welded onto the hot spot, a hole lanced through it and a cap fitted.   The kiln is then rotated a few more times, and stopped with the nipple at the bottom.  

Versimould or "Versiject" is then pumped through the nipple and the missing lining is replaced.   15 minutes after stopping, the kiln must be rotated again.   The total downtime is only about half an hour.  Another characteristic of Versimould is that it expands during setting. This is a result of the impermeable nature of the bond plus the heat of reaction, which causes trapped bubbles of gas to expand.   This property makes it ideal for sealing applications.   It is particularly useful when doing pumping repair of cracks.   All cracks are sealed superficially with "Versimould Plug", leaving only one orifice with a pipe sticking out.   The pump nozzle is attached to the pipe and the material injected.   Any other material applied to a hot crack would fail to seal it.

There are certain applications where normal refractories would fail due to impact.   We have done quick repairs on hot boiler panels with "Versimould Panel".   These heavy panels get unavoidably bumped against the superstructure during installation, and only Versimould can survive the impact. Versimould is also useful for applications where high thermal gradients are involved and cracking is undesirable. The last application is hot repair of small areas of furnaces.   It is possible to repair minor damage very quickly with Versimould, and once installed, the furnace can be switched on immediately.   This can save many hours to days of downtime.

Versimould is so named because of its versatility.   Each of its properties gives it certain niche applications. It bonds well to steel, and the phosphate also inhibits corrosion of steel. Another obscure application is "Welding Aid".   Have you ever battled to hold several pieces of metal in position simultaneously while welding them?   Stick them together with welding aid.   It can also be used to make a bath of weld material, or to protect cetain areas from the arc. About 10 years ago I made a Versimould concoction to patch my Kombi's silencer.   The patch outlasted the rest of the silencer.   I spilled a few blobs on my tarred driveway, and they are still there today!  

Technical feature:

                          EXOTHERMIC MATERIALS

Many chemical reactions give off heat, and I want to point out some of the consequences.   The first and most important thing to remember is that the heat is dissipated through the material.   Therefore a thin layer of exothermic setting material will show very little rise in temperature.   A large mass on the other hand will get very hot.   The inside of the mass will get even hotter than the surface.   Large castings of Keraset (Magnesium oxychloride) generate enough heat to explode.   Explosion occurs as soon as the steam pressure exceeds the tensile strength of the bond.   Cornelia de Villiers invented a remarkable material by accident.   She made a batch of "Corkalium", a magnesium oxychloride bonded cork-chip flooring mix, in a nappy bucket. The mix started getting very hot and eventually boiling.   She sent her assistant out into the street with it, where it started erupting and exploding.   The resulting pieces of product were remarkably light but very hard.   I tried in vain to reproduce it in the lab.   I pestered Cornelia about her formulation, but she consistently gave the same details.   Eventually it dawned on me that the material cannot be made on a small scale without insulation or heat input.

Trapped gases in an exothermic material will expand with the heat, and cause the casting to bloat.   The best way to combat this is to start with cool materials, keep the castings small and cool them as far as possible during setting.   Use metal oulds in preference to wood.

Pyromould is an exothermic material of a different nature.   It is a concoction of pyrotechnic and refractory materials.   The installation is ignited at one point, and the reaction proceeds in a wave through the body.   Any given point in the body rises suddenly from ambient temperature to about 500øC and then gradually cools.   The temperature reached is not related to the size of the installation.   Pyromould's main application is ramming the joint between the furnace and a precast and dried launder.

I have just driven to Salt Rock for a long weekend. The road was busy and there were queues at the toll gates. The army taught me to hate queues, and I have already spent far too much of my life in them. I noticed that there were on average two unmanned toll booths per toll gate. The queues were therefore totally unneccessary.   

I experimented with driving through the empty ones with the red crosses above them. At worst I had to drive over a road cone or two. At best I got a toll collector going hysterical, which I found quite gratifying.  

South Africans are world renowned for their apathy and complacency, which is why we always get such bad service.   Let's start doing something about it. Call it "affirmative toll paying". When you arrive at a toll gate and there are queues  and some of the toll booths are unmanned, drive through. If enough people do it, the toll operators will be forced to spend that tiny bit more to pay enough staff to prevent queues. 

This is the New South Africa, let's be positive in everything we do and make it a better place to live in.


Keramicalia have become the West Rand agents for Alusil gold pots.  Alusil Refractories in Springs have a reputation for being the most innovative furnace builders in South Africa. Amongst their achievements is char plant built and comissioned in their factory, then dismantled and shipped overseas. Eddie Fullard invented the monolithic gold pot.   He started with a brick lining in sections, and developed the technology step by step until the present complete unit with a prefired lime-free lining. Naas van Heerden, previously of Elgin and later Tugela Alumina, handles sales. 

Product feature - KERAPOUR

Kerapour is a most unusual material. It combines most of what one wants from a refractory lining. It can resist molten metal contact, which is the downfall of most insulation materials. This can be demonstrated by making steel in a crucible of Kerapour. We use the "thermit" process, a dramatic chemical reaction between iron oxide and aluminium.  

Incidentally, we repair slag pots by this process. Maybe we will use the subject for another newsletter.

Kerapour is a viscousbut free flowing, self-levelling material. Just add water, mix and pour.                                     

Kerapour is frequently called on to do miracles. At Sappi's Enstra mill, a brick lining in their furnace had come loose.   Here Kerapour was called on to fill the cavity and cement the lining, otherwise it would have to be re-bricked, and the shutdown would cost a fortune.  I built a "swallow's nest" funnel out of Versimould Plug in the rather restricted doorway which was my only access to the crack leading to the cavity. I call this funnel structure a "swallows nest", because it is built up in layers similar to a swallows nest. It looks more like a swft's nest. Into this cup we poured Kerapour, and we poured and poured. Eventually we got half a ton in. The Kerapour leaked out of a few small holes which we plugged with Versimould Plug as they appeared. When the furnace was eventually rebuilt, we were able to determine how far the Kerapour had flowed; it had flowed for ten metres horizontally!

Some time later the same plant had a crack in the brickwork of a boiler arch. The air leaking through was causing premature ignition on the chain grate and destroying the breast plate and guillotine.  A shutdown was already programmed to rebuild the arch at a cost of R30 000.   I asked the engineer to give me just one day to try blocking the crack with Kerapour. We studied the drawings and found the appropriate points to introduce the Kerapour.   We poured some in and sure enough it emerged through the crack over the whole length of the arch and sealed it. The boiler worked perfectly again.

Lance Pretorius of Natal Foundry Suppliers also did a neat "Red Adair" style repair on a gas leak at Sapref with Kerapour.   A number of options were considered, and eventually Kerapour was chosen as the only safe option.   It worked perfectly; a tribute to the properties of "cellular" insulation.

Cellular insulation is the answer to heat conservation in ladles.   A backlining of Kerapour ensures a steel tight seal, as can easily be demonstrated in the thermit crucible test.   Installation requires a casting former, which is not always available, so tiles are also made, for installation with Kerasil mortar.   (Kerasil mortar is used because it is important to leave no gaps.)   Tiles have proved themselves at Siltek and Scaw metals, and are now being offered for large ladles.

A basic version of Kerapour has now been developed at the request of some customers.   Incidentally, we also have a basic insulating water-free mortar for use in contact with dolomite brick.   It is particularly useful for preventing steel from getting behind the dolomite bricks, and helps to make breaking out easier.

Readers' contributions

Some readers want to know what a "contirution" is.   Isn't it something to do with tying your body in a knot?   Somebody reckoned it was either a printer's gremlin or the word processor reminding us to pay the installment.  


Several readers want to know why we didn't tell them years ago about Multimould.   Sorry, but that's the purpose of this newsletter.   Two products down, about 50 to go.

Technical feature


Selling insulation by the kilogram has always been a hazardous occupation.   Customers usually get the impression that good insulation materials are expensive.   Furnace builders usually have more insight and immediately recognise a good insulation material as a bargain. To help evaluate new materials, I have developed a comparison which I call the "Heat containment cost factor".   By definition it is the cost per square metre of a large furnace wall to reduce the temperature from 1000øC to 115øC. The average castable or brick has a thermal conductivity of around 1,3W/mK and a density of around 2,4g/cmþ.   To reduce a furnace temperature from 1000 to 115øC we need 130cm of castable,to give us a K value of 100.   One therefore requires 312kg per square metre, and say it costs R1 400/ton, the heat containment cost factor is R436.80.  Heat containment cost factors for working linings are around this figure of 450 for aluminosilicate materials, and around  for basic materials. Kerapour has a thermal conductivity of around 0,3W/mK, a density of 1,1g/cmþ and cost of R3 500/ton. This gives a heat containment cost of R25.41  i.e. it costs one tenth as much as normal materials to do the job of keeping the heat inside the furnace.

Let us take a simple example:   Say we have a small furnace of 100mm square. We want a temperature of 1000øC inside the furnace and a cold face temperature of 115øC.   To achieve this with a conventional castable or brick with a thermal conductivity of 1,3W/mK we would need a thickness of 130mm   The total volume of material would therefore be 45 litres, weigh 108kg and cost R151.   In Kerapour, we would need a thickness of 30mm, use 3,1 litres, weigh 3,4kg and cost R12, i.e. less than a twelfth of the price of normal dense materials.   If you built the same out of basic brick, which would be daft, it would weigh 6 tons and cost 1000 times as much as Kerapour!

Note that the energy consumption drops drastically with good insulation and the speed of heating up increases drastically. Please let us do an exercise on your furnace to see if we can help. Fax us your dimensions, operating temperature and present lining design.