WASHING, in painting, is when a design, drawn with a pen or crayon, has some one colour laid over it with a pencil, as Indian ink, bistre, or the like, to make it appear the more natural, by adding the shadow of prominences, aperture, &c. and by imitating the particular matters whereof the thing is supposed to consist.
Thus they wash with a pale red, to imitate brick and tile; with a pale Indian blue, to imitate water and slate; with green, for trees and meadows; with saffron or French berries, for gold or brass; and with several colours for marbles.
WASHING of Ores, the purifying an ore of any metal, by means of water, from earths and stones, which would otherwise render it difficult of fusion.