Core-wash
A special manufacture, intended to supersede the ordinary blackings mixed in the foundry.
This wash is a preparation of black lead and other materials. It makes a hard skin or veneer on the mould, which does not rub off nor run before the molten metal while the latter is flowing into the mould, and consequently the castings come out "sound, smooth, and perfect." The wash is applied with a brush to the mould, and when a very smooth surface is desired on the castings, it is applied before drying and smoothed with a slicker; while for ordinary work the wash can be used before or after it is dried, while the mould is still hot, and without smoothing.
For very heavy work two or even three coats may be applied, to insure the best results. See FACING.