The thermal decomposition products of the organic resins used in the foundry to bind moulding sand contain elements, in particular carbon and possibly also sulfur and nitrogen, likely to diffuse to the surface pollution, in particular the recarburizing, impairs corrosion resistance. After the mechanism and effects of this recarburizing were determined and the level of harmfulness of various resins commonly used as binders in steel casting was tested, an effective remed y was developed: an oxidizing aqueous coating free of organic substances. Applied to the mould, this coating, which may be based on a zircon or corundum refractory, completely and significantly limits nitrogen diffusion. It is patented in France and Europe, and is now marketed by the ASHLAND-AVEBENE company.
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