This is a mixture used by painters to cover their work when they are obliged to leave it for some time. It may be washed off with a sponge and water, so as to leave the painting in the exact state in which it was when work was suspended. It is composed of pale nut-oil, 6 ozs.; mastic, 1 oz.; sugar of lead, previously ground in the least possible quantity of oil, 1/4 oz. Dissolve the mastic in the nut-oil, add the sugar of lead, and then add water, beating the mixture all the time until it looks like cream.

Another recipe is as follows: Take of very clear nut-oil 3 oz.; mastic in tears, pulverized, 1/2 oz.; sal saturni, in powder (acetate of lead, 1/3 oz. Dissolve the mastic in oil over a gentle fire, and pour the mixture into a marble mortar, over the pounded salt of lead; stir it with a wooden pestle, and add water in small quantities, till the matter assumes the appearance and consistence of cream, and refuses to admit more water.