Black-wash
A refractory mixture for coating the surfaces of loam and dry-sand moulds and dry-sand cores, to protect the sand from burning by the interposition of a coat of carbon between it and the molten metal. The compositions for this purpose are various, but the principal ingredients entering therein are charcoal-dust, silver lead, mineral, and hard Lehigh blacking; these, in varying proportions, are mixed with thin clay-water to a suitable consistency and applied with a swab or brush. See FACING.