Note 20 — Chapter VIII

(p. 55.) There is another method of getting what may be called a proof, i. e. by taking a cast in plaster. Ink your plate and wipe it clean, as described in Note [22], and then pour over it plaster-of-Paris mixed with water. When the plaster has hardened it can easily be separated from the plate, and the ink in the lines will adhere to it. To make such a cast you must manage a rim around your plate, or you may lay it into a paper box, face upward. Mix about half a tumbler full of water (or more, according to the size of the plate) with double the quantity of plaster, adding the plaster, little by little, and stirring continually. When the mixture begins to thicken pour it on the plate, and if necessary spread it over the whole of the surface by means of a piece of wood or anything else that will answer. Then allow it to harden.