Zircon mould and core coatings for mild steel and stainless steel castings
Steel pours hot, and on a sand mould the metal has time to penetrate between the grains, react with the silica and burn on, leaving a skin that has to be chipped and ground off every casting. A refractory wash on the mould and core faces is what stands between the melt and the sand. Pyroflux India formulates three zircon washes for heavy mild steel, stainless and alloy steel castings: Maxcote 100, water-based and brushed straight from the can; Technomol 256, alcohol-based for flash drying; and Isocote 100, a high-zircon thixotropic paste for the most coverage per kilogram. All three also serve heavy nickel, copper, brass, bronze and gun metal castings, and alumina-silicate and graphite washes cover grey iron, SG iron and non-ferrous work. Ready for use, 30 kg packs, from the formulating bench in Noida.
What goes wrong without the right wash
- Metal penetration. Liquid steel enters the pores between sand grains, especially on heavy sections and in hot spots, and solidifies as a sand–metal crust that must be ground off.
- Burn-on and sand fusion. Silica sand softens against steel pouring temperatures; the skin fuses to the casting and the mould face is lost.
- Veining and erosion. Cores and mould edges wash away under the metal stream, leaving fins, veins and inclusions.
- Poor surface finish. A rough or reactive mould face prints straight onto the casting, adding fettling time on every piece.
A zircon wash answers all four: zircon is dense, chemically inert to steel and does not wet, so the melt stops at the coating and the casting peels clean.
Which coating for which metal
| Grade | Carrier and form | Use it for | On the floor | Packing |
|---|---|---|---|---|
| Maxcote 100 | Water-based, ready-for-use zircon wash | Heavy MS, SS and alloy steel castings on most sand binders; heavy nickel alloys, copper, brass, bronze and gun metal | Brush straight from the can; dilute with water about 8:1 to spray. Air-dry about 15 minutes, then torch or oven bake. Builds a crack-free refractory layer up to 1 mm in one coat | 30 kg bucket |
| Technomol 256 | Alcohol-based, ready-for-use zircon wash | Heavy MS, SS and alloy steel castings in green sand and CO₂ processes; heavy nickel, copper, brass, bronze and gun metal | Remix, brush or spray, and flash off. Typically 10–15% dilution for brushing, 25–30% for spraying; on large faces apply in parts and ignite each at once. High filler-to-solvent ratio gives high coverage | 30 kg polycarboy |
| Isocote 100 | Alcohol-based high-zircon thixotropic paste | Steels, iron, nickel and copper based castings; all sand binders | Dilute with ethyl alcohol or IPA to the consistency the method needs, brush or spray. Highest zircon content, so the most coverage per kilogram | 30 kg polycarboy |
Beyond the three zircon washes, the same bench makes the rest of the mould and core coatings a ferrous and non-ferrous foundry uses:
| Grade | Carrier | What it is |
|---|---|---|
| Mouldcote MG | Solvent | Ready-for-use magnesite coating for manganese steel castings |
| Maxcote 210 | Water | Ready-for-use graphite coating for iron and non-ferrous castings |
| Mouldcote GR | Solvent | Ready-for-use graphite coating for iron and non-ferrous castings |
| Technocote 60 | Water | General-purpose water-dispersible graphite coating for ferrous and non-ferrous castings |
| Technopaint 212 | Water | Graphite paste for dip coating of shell and hot-box cores |
| Viscotec XL | Water | Ready-for-use dip coating for cast-iron automotive castings |
| Suncote 11 | Water | Semi-colloidal graphite suspension used as a mould release agent |
| Ladlecote 100 | Water | Zircon coating for ladles and launders |
| Maxcote 110 | Water | Protective coating for furnace refractories |
Maxcote 100 suits shops that air-dry and then torch or oven bake; Technomol 256 and Isocote 100 flash-dry with a torch and are the usual choice for cores and for moulds that go straight to the pouring line. Solids, density and coverage are on the data sheets; request them here.
Getting a consistent coat
- Remix the coating thoroughly; Maxcote 100 brushes straight from the can, Technomol 256 and Isocote 100 are diluted with alcohol as the data sheet directs. Keep a density check on the line.
- Apply by brush, swab, spray or dip to a clean mould or core face; one even coat is better than two heavy ones.
- Air-dry Maxcote 100 for about 15 minutes, then torch or oven bake; flash off the alcohol-based grades with a torch at once, in parts on large faces.
- Inspect for runs, pinholes and bare patches before closing the mould; touch up by brush.
- Record density, coat count and drying for each pattern so the finish repeats from one heat to the next.
For the rest of the foundry
Centrifugal casting die coatings
Spuncote 100, 200 and 300: water-based alumina-silicate, alumina and zircon coatings for spun pipes and cylindrical castings.
Read more →Covering and refining fluxes
For non-ferrous melts: covering, drossing and refining fluxes from the same bench.
Read more →High-temperature ceramic coatings
Supracoat for ladles, launders, furnace fixtures and refractory surfaces to 1750 °C.
Read more →Common questions
Do you supply zircon coatings for stainless steel castings?
Yes. Maxcote 100, Technomol 256 and Isocote 100 are all formulated for heavy MS, SS and alloy steel castings, because zircon does not react with the melt at pouring temperature. Tell us your sand system and drying method and we recommend the one that fits.
Water-based or alcohol-based?
Maxcote 100 (water-based) suits shops that can air-dry and then oven or torch bake before pouring, and avoids solvent on the floor. Technomol 256 and Isocote 100 (alcohol-based) flash-dry in seconds and are preferred for cores and for moulds that close straight after coating. All three carry zircon.
Which one gives the most coverage per kilogram?
Isocote 100, the high-zircon thixotropic paste, followed by Technomol 256 with its high filler-to-solvent ratio. Maxcote 100 is chosen for convenience: brushed straight from the can with no mixing, and a layer up to 1 mm in one coat.
Will a zircon wash stop penetration on heavy sections?
In the great majority of cases, yes, provided the coat is even, dried properly and the density is held. Where a section is very heavy we may recommend a second coat or a higher working density, which we set during a trial on your pattern.
Do you send a data sheet?
Yes. TDS and SDS go out by email within one working day of a request, with the dilution and drying guidance for the grade.
Tell us the metal and the sand; we will recommend the wash
Metal and grade, sand system (green sand, CO₂-silicate, resin), section thickness, and whether you oven-dry or torch-dry. That is everything we need to recommend a grade, quote and send a trial pack.
- Phone
- +91 98181 87838
- sales@pyroflux.in
- Office
- G-5, Sector 63, Noida 201301, Uttar Pradesh, India
- Factory
- G-15, Sector 63, Noida 201301, Uttar Pradesh, India
- Hours
- Monday to Saturday, 9 am to 6 pm IST