Induction Materials

1. Induction Coil Coating: A hard, strong, 93% alumina putty for protecting coils. Use it between coils and as a thin cover to prevent molten metal contact.

2. Kerasic: A hard strong, abrasion resistant material for inside the coils. Make it into a sleeve or skid rails.

3. Hollocast 1: An inexpensive, pleasure to install, quick setting insulation material. Use it as a support outside of the coils to keep them straight and in line. Easy to break out without destroying the coils.

4. Elmotherm® VA42: An insulating paint to prevent electrical shorting between coils.

5. Electrical Paint: A higher temperature resistant alternative to Elmotherm. Use on slings. Dip the sling into the paint, switch it on for 5 seconds and remove it. Switch on for another 10 seconds to dry and harden it.

6. Kerinduct 2: A dry spiking lining of spinel forming composition. Expands on sintering to make a tight lining. Use as a working lining in coreless induction furnaces for melting stainless steel and high temperature alloys.

7. Chloresist: A solid, almost impervious castable lining for channel induction furnaces. Use for zinc especially.

8. Mica Sheet: Use for a slip plane between Kerinduct 2 and the Induction Coil Coating.

9. Asbestos Board: A durable, heat resistant board for the end plates of induction coils and the tops of coreless induction furnaces. We stock boards 1m x 1m x 20mm.

10. Capping: A very fast setting material to give a decent hard capping against which a “gwala ” can be levered. It requires no heat to set.

11. Kerapatch Stainless: An excellent hot patching material.

12. Slag Coagulant: To thicken the slag and enable its removal.

13. Keratherm: An insulation cover which spreads nicely. Carbon free.

14. Keraplas Ramming: An excellent ramming material with green chromic oxide.


Description: A refractory material for resistance to chlorides.
It has low permeability and actively scavenges chlorine to form sodium chloride.

Applications: Incinerators burning PVC. Vessels in which metal chlorides are reacted. Protection from chlorine or HCl vapors.

Add +17% Hardcast Binder to Chloresist powder and vibration cast, or
Add +30% Hardcast Binder to Chloresist powder and pour it.
Use gloves, the material is highly alkaline.

Wet vibrated density: 2.3g/cm³
Wet poured density: 2.1g/cm³

Packaging: 22kg polythene bags of powder plus 6.5kg polythene bottles of Hardcast binder.

Electrical Paint

Description: A refractory coating with low electrical conductivity. Air drying. Consistency similar to household paints.

Composition: Fine reactive alumina bonded with colloidal silica, plus normal organic binders and suspension agents.

Melting point: About 1850°C.

Density: 2kg/litre.

Coverage: Smooth surfaces: 250g/m².

Rough surfaces: 1.1kg/m² plus a second coat of about 500g/m2.

Uses: Covering iron spotted bricks in contact with elements. Reinforcing ceramic fibre blanket/modules. (Dilute with +100% water and apply about 4kg/mý.) Cosmetic coating of refractory structures. Increasing reflectivity of furnace surfaces. Sealing fine cracks to reduce gas leakage.

Stir the bucket well.
Apply with a paint brush.
Clean brushes with water.

Packaging: 2kg, 10kg and 20kg plastic buckets. Ready mixed.

Elmotherm® VA42

Single component, anti-tracking, fungicidal varnish, suitable for transformers,

motors and windings.

Product description:

Elmotherm® VA 42 is a single component, impregnating varnish, based on a specially alkyd modified resin with long-term tank stability and a thermal rating of 155-180 °C.

The product consists of a polymeric binder, the so-called solid content and a solvent mixture.

Reducer X2 will be available for the dilution of the varnish. It is designed for use in applications where high bond strength and or good moisture and chemical resistance is required.

Polymerization is initiated by the effect of atmospheric oxygen and proceeds as a rapid chain-reaction until a three-dimensionally cross linked, duroplastic cured material is produced.

The product fulfils the directive 2011/65/UE e 2002/95/CE (RoHS).

The raw materials of the product are pre-registered according to directive to CE 1907/2006 and s.m.i. (REACH).

The product does not contain polycyclic aromatic hydrocarbons and substances listed in the SVHC Candidate List.

Areas of application:

Preferred applications for Elmotherm® VA 42 are:

  • Transformer
  • Stator
  • Drive in the chemical industry
  • General use

Properties of cured resin:

The tough-hard material shows very good mechanical and dielectric properties even under high temperatures. Windings impregnated with Elmotherm® VA 42 show good bond strength.

In addition, the cured material displays good resistance to the effects of liquid chemicals and their vapors. Owing to the high temperature index of 180°C (acc. UL= Underwriters Laboratories USA). Elmotherm® VA 42 can be used for electrical machines from 130°C to 180°C.

Flow time (viscosity):

Elmotherm® VA 42 is produced with a relative low viscosity: 160-200 sec measured with Ford 4-cup at 25°C (ø4 mm acc. ASTMD1200).

The kind of processing, e.g. with higher ambient temperatures, leads to rising losses of solvent and increased flow time.

In this case it will be necessary to adjust the flow time by addition of reducer X2.

Processing methods:

Elmotherm® VA 42 is using as a finishing varnish or as impregnating varnish.  The impregnating process has to be carried out with a corresponding impregnating material.

The flow time of air-drying varnish in opened container will increase permanently due to the evaporation of solvent, film forming can occur additionally. Therefore the containers should be closed carefully after application, the flow time should be checked frequently and adapted with reducer X2 if required.

Like all solvent based products Elmotherm® VA 42 should be stirred up carefully before each application.

Elmotherm® VA  42 can be applied by dipping, brushing, with flow time when delivered.

When it is used by spraying, it is recommended to add 10-20% of reducer X2.

Drying of the varnish will be at ambient temperature normally, time can be shortened by support of heat, for instance with hot air at 70-90°C.

It will be necessary to follow the instructions of the Material Safety Data Sheet (MSDS) for varnish and reducer.

Storage and stability:

Under appropriate storage conditions, protected from humidity and solar radiations, Elmotherm® VA 42 and reducer X2 can be stored in unopened containers at 23°C for 24 months.

Properties of varnish as supplied:

Property Value Unit
Shelf life at 23°C 24 Months
Appearance/Colour Liquid/red oxide
Density at 23°C, DIN 51757 960-1020 g/l
Content of binder (1,5 g/1h/135°C), ISO3251 54-60 %
Flow time at 25°C ford 4 cup, ASTM D1200 160-200 sec
Flash point 25 °C


Drying condition:

Surface 23°C 80°C
Touch-dry 15-20 min 3-5 min
Non slip 2 h 15 min
Fully dried 24 h 2 h


Mechanical properties in dried condition:

Test criterion Condition Value Unit
Bond strength, Elantas test

following 61083 method (helical coil)








Mandrel test (3 mm) Elantas test

Following 60464-3

23°C 150 °
Adhesion on steel UNI EN ISO 2409

Double application

40µ 100 %


Temperature Index: 

Test criterion Condition Value
Proof voltage Elantas test following IEC

60172 (twisted pair)

1000 V 180


Dielectric properties in dried condition: 

Test criterion Condition Value Unit
Volume resistivity after water immersion

Elantas test following IEC60464 part 2

Initial value

7 d storing



Ω x cm
Volume resistivity, at elevated temperature

Elantas test following IEC60464 part 2





Ω x cm
Electrical strength, after water immersion

Elantas test following IEC60464 part 2

Initial value

24 h storing


Electrical strength, at elevated temperature

Elantas test following IEC60464 part 2





Temperature at relative permittivity tang °=0,1

Elantas test following IEC 60250

50 Hz

1 KHz

10 KHz





Effect of liquid chemicals, including water: 

Test criterion Condition Value Unit
Resistance to vapor of solvents

Elantas test following IEC 60464 part 2





Carbon disulphide






Water absorption

Elantas test following IEC 62

At 23°C

0,5 h at 100°C




Hollocast 1

Description: Hollocast is a refractory castable with a high insulation value yet high strength and resistance to thermal cycling.

Composition: Hollocast has a very fine microstructure and low permeability, yet the total porosity is 40%. The porosity is largely in the form of minute hollow alumino-silicate spheres of “Hollofill.”

Physical properties: Hollocast mixed with +18 to 21% water gives the following properties after firing to 1300°C.:

C.C.S: 20MPa.

Bulk density: 1.6g/cm³ (S.G. 2,75)

Total porosity: 40%

Permanent linear change: -0.8%

Thermal conductivity:

200°C 0.49W/mK
400°C 0.5 W/mK
600°C 0.52W/mK
800°C 0.55W/mK


Applications: Replaces all traditional “semi-insulation” materials; Hot face linings for ladles to reduce sculling. Soaking pit roofs, especially where Detrick bricks are used as anchors. Any roofs where a weight saving can reduce the structural support system. Brick kiln roofs. Insulation applications which are subjected to mild abrasion. Heat treatment bogeys. Intricate kiln furniture. Places where access is limited or difficult. High thermal shock applications. Aluminium launders, ladles and holding furnaces.

Installation: Mix with about +19% water to +23% water and place by pouring

DO NOT VIBRATE, it will cause segregation and failure.

Pilot plant codes: OTO OZW and PGJ

Hollocast 1 Incinerator lining after 2 years of installation

Clean out ladle completely. Fit well block and purge cone seating block with mortar. Cover sides of well block and seating block with cardboard and wrap with buff tape to leave gap for ramming. Cover top of well block and seating block with cardboard or a lid of some sort. Make mark on a trowel or stick to measure required floor thickness. Place a pan mixer next to the top of the ladle and make a discharge chute to pour directly into the ladle. Remove the ladder from the ladle. Weigh out or measure in buckets, 32 litres of water. Place 8 x 20kg bags of Hollocast in the mixer. Start the mixer and dump all of the water rapidly into it. Mix for about 20 seconds and then add a further 4 litres of water to bring the mix to a very fluid consistency. (+22.5% water). Open mixer gate and discharge the whole mix directly into the ladle. Place the ladder back in the ladle, go down and check the thickness of Hollocast next to the purge plug seating block is approximately correct, using your prepared measure. Sweep material towards the edges of the ladle floor if it is flowing too slowly. Get out and remove the ladder. Clean out the residue from the mixer into an empty bag, to monitor setting time. The Hollocast will stop flowing after about 10 minutes. Once the setting sample in the bag is hard and warm, you may fit the former. (About an hour.) Repeat procedure for sidewalls.

Drying: Place ladle under the preheater and heat to 150°C for 3 hours. Raise temperature to 400°C and hold for 3 hours. Allow to cool and continue bricking the side up.

Hollocast 1 user references

* Armitage Shanks: 012 316 2571 Hennie van der Bank. Use it for sanitary ware kiln furniture, cycling through 1120°C daily. They find that its abrasion resistance is better than that of dense castable in their application.
* Aztek Furnace Services: 016 22 3414 Billy Wolmarans. Heat treatment furnace floors.
* Bohler Steel: 011 974 2781 Frank. Large heat treatment furnace floor.
* Custom Furnaces: 016 365 5723 John Lee Use it for all furnace floors, even forges.
* Fibreline: 016 54 020 John and Phillip Havenga. Used around 4 tons per month.
* Iscor Pilot Plant: 012 318 7785 Paul Hloben. Tested on project codes OTO, OXW, and PGJ.
* Pressure Die Casting: 0331 72327 Colin Belsham. Aluminium furnaces. Good resistance to thermite reaction.
* S.A.A.: 011 978 6298 Isaac van Rensburg Relined Wild-Barfield furnace with complex element bricks made from Hollocast. Also a large very flat heat treatment furnace floor.
* Darton: 011 432 0086 Darryl & Alan. Various furnaces.
* Microsteel: Insulation on floors of dolomite lined ladles.
* LTL Abrasives: 011 412 2920 Mike Reid. Furnace floors.
* Zimalco: Aluminium ladle linings. Kim Garner, 011 914 4300
* S.A. Metals: Ladle and tundish backlinings. Peter Lumley, 021 590 3943

Induction coil coating

Description: A high density plastic alumina refractory. It has high strength and abrasion resistance and good electrical insulation once dried.

Installation: Supplied as powder, to which +12 to+13% water must be added for a stiff putty consistency, or more water for a soft coil embedding consistency.

Applications: Areas where combinations of high strength, abrasion resistance, high thermal conductivity and zero electrical conductivity are required. Main uses are; Filling the spaces between induction coils, Embedding elements around muffles.

Chemical Analysis:

Al2 O3 97.0%
Fe2 O3 0.01%
SiO2 0.01%
CaO 3.0%
Na2 O 0.25%

Colour: White

Maximum particle size: 1mm

Packaging: 25kg plastic bags

Shelf life: 18 months

Development number: 24698

See Keratab Ultrafine: Similar material, self-flowing and self-levelling.


Description: Kerasic is alumina bonded silicon carbide. The main problem with silicon carbide is that it oxidizes to silica. The alumina bond reacts with the silica to form a mineral called mullite, which has a needle like structure and imparts high strength, and has a melting point of 1850ºC. Kerasic is not as electrically conductive as other silicon carbide materials. Kerasic is a very fine grained material which can be poured like thick cream. Very detailed castings can be made with wall thicknesses down to 2mm. Plates have been made 300mm x 300mm x 5mm thick. The surface texture is very smooth, and the abrasion resistance of fired parts is excellent. The strength increases with repeated firing.

Cold crushing strength: 50 – 120 MPa

Chemical analysis:

Al2 O3 34.0%
SiO2 2.0%
SiC 58.0%
CaO 6.0%


Packaging: 25kg plastic bags.

Water addition for pouring: +12% vibration casting; +9%

Kerinduct 2

Description: A spinel forming alumina induction furnace lining.

The aggregate is fused chrome alumina and the fines are high purity sintered and reactive aluminas and 12% dead burned seawater magnesia.

There is no frit addition.

Sintering is by spinel forming reaction which gives expansion and a tight sealed hot face, with powder behind it to prevent crack propagation.

Maximum Services temperature: 1750°C

Density: Hand rammed density is 2.9g/cm³

Chemical Analysis:

Total Aggragate Alumina Fines
Al2O3 80% 87% 99.7%
Fe2O3 1.2% 2% 0.02%
Cr2O3 6% 10%
SiO2 0.2% 0.2% 0.04%
CaO 1.4% 2% 0.04%
Na2O 0.06%
K2O 0.6% 1%
P2O5 0

Sintering: 12 hours on low power, then 2 hours at 1680 – 1700°C

Packaging: 25kg plastic bag

Shelf life: 6 months