Metal casting sand additive - used to prevent casting flaws

Additive for metal-casting shell mould and core sand comprises castor oil-impregnated wood flour contg. >=90% particles of size 0.05-0.7 mm. Appln. is esp. in presence of tert. amines with isocyanate-reactive phenolic resins. Risk of casting flaws is reduced, and stability to humidity during storage is improved.