(p. 52.) M. Lalanne, it seems to me, does not do full justice to zinc plates. Very delicate lines can be bitten on zinc if the acid is sufficiently weakened. I have found that one part of nitric acid to eight parts of water, used on zinc, is about equal to one-half acid and one-half water, used on copper for about the same length of time. Zinc plates can also be bought of Mr. Geo. B. Sharp, 45 Gold St., New York. As to the length of edition that can be printed from a zinc plate, see Note [27].
(p. 52.) This is not strictly correct. The “manière de crayon,” as practised by Demarteau and others, differs materially from soft-ground etching. A ground was laid and smoked as usual, and on it the drawing was produced, by a variety of instruments, such as points, some of them multiple, the roulette, the mattoir, etc.
(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.
(p. 55.) The chafing-dish and the ball (or dabber) are now replaced by the gas flame and the inking-roller in most printing establishments. But if you desire to do your own proving, you will have to use a dabber, the manner of making which is described in the [next note].
(p. 59.) If there is no plate-printer near you, but you have access to a lithographic printing establishment, you can have your proofs taken there. “Lithographic presses,” says A. Potémont, “give perfectly good and satisfactory proofs of etchings.”
Not every printer can print an etching as it ought to be printed. A man may be an excellent printer of line engravings and mezzotints, and yet may be totally unfit to print an etching. I would recommend the following printing establishments:—