Part 5 (1/2)

In order to impress the gilt figures on the leather covers of books, the leather is first dusted over with very fine powdered resin or mastic; then the iron tool by which the figure is made is moderately heated and pressed down upon a piece of leaf gold which slightly adheres to it, being then immediately applied to the surface of the leather with a certain force; the tool at the same time makes an impression, and melts the mastic which lies between the heated iron and the leather; in consequence of this, the gold with which the face of the tool is covered is made to adhere to the leather, so that on removing the tool a gilded impression of it remains behind.

PRINc.i.p.aL COLORS OF GOLD FOR GRINDING.

The princ.i.p.al colors of gold for grinding are red, green, yellow. These should be kept in different amalgams. The part which is to remain of the first color is to be stopped off with a composition of chalk and glue; the variety required is produced by gilding the unstopped parts with the proper amalgam, according to the usual mode of gilding. Sometimes the amalgam is applied to the surface to be gilt, without any quicking, by spreading it with aquafortis; but this depends on the same principle as a previous quicking.

WRITING ON METALS.

To write on metals, take half a pound of nitric acid and one ounce muriatic acid. Mix and shake well together, and then it is ready for use.

Cover the plate you wish to mark with melted beeswax; when cold, write your inscription plainly in the wax clear to the metal with a sharp instrument. Then apply the mixed acids with a feather, carefully filling each letter. Let it remain from one to ten hours, according to the appearance desired, throw on water, which stops the process, and remove the wax.

HOW TO TRANSFER A PHOTOGRAPHIC PRINT TO GLa.s.s.

To transfer a photographic print to gla.s.s for painting or for other purposes, separate the paper print from the background by steaming it; dry thoroughly, and having given the warmed gla.s.s an even coating of clean balsam or negative varnish, place the face of the print on the surface thus prepared, smooth it out and let it stand in a cool place until the varnish has hardened. Then apply water, and with a soft piece of gum-rubber rub off the paper so as to leave the photographic image on the varnished gla.s.s.

STEREOTYPING WOODCUTS.

In stereotyping woodcuts, care should be taken that they are thoroughly dry before being sent to the foundry, as the intense heat to which they are subjected frequently causes them to warp and split, especially if pierced.

TO GILD WITH GOLD LEAF.

Bookbinders use gold leaf in two ways--to gild on the edge, and to place gold letters on the binding. To gild on the edge, the edge is smoothly cut, put in a strong press, sc.r.a.ped so as to make it solid, and the well-beaten white of an egg, or alb.u.men, put on thinly; the gold leaf is then put on before the alb.u.men is dry; it is pressed down with cotton, and when dry polished with an agate polisher. To put on the lettering, the place where the letters are to appear is coated with alb.u.men, and after it is dry, the type to be used is heated to about the boiling point of water, the gold leaf is put on, either on the book or on the type, and then placed on the spot where the lettering is desired, when the gold leaf will adhere by the heat of the type, while the excess of gold leaf loosely around is rubbed off with a tuft of cotton.

GILDING ON WOOD.

To gild in oil, the wood, after being properly smoothed, is covered with a coat of gold size, made of drying linseed oil mixed with yellow ochre.

When this has become so dry as to adhere to the fingers without soiling them, the gold leaf is laid on with great care and dexterity, and pressed down with cotton wool. Places that have been missed are covered with small pieces of gold leaf, and when the whole is dry the ragged bits are rubbed off with cotton. This is by far the easiest mode of gilding. Any other metallic leaves may be applied in a similar manner. Pale leaf gold has a greenish-yellow color, and is an alloy of gold with silver. Dutch gold leaf is only copper colored with the fumes of zinc. Being much cheaper than gold leaf, it is very useful when large quant.i.ties of gilding are required in places where it can be defended from the weather, as it changes color if exposed to moisture; and it should be covered with varnish. Silver leaf is prepared like gold leaf, but when applied should be kept well covered with varnish, as otherwise it will tarnish. A transparent yellow varnish will give it the appearance of gold.

GILDING IN OIL.

In order to make good work in oil gilding there are several indispensable conditions which must be observed. First, a smooth ground. Second, gold size free from grit or skins. Third, in putting oil gold size on the work it must be dross black, ground in turpentine, and mixed with boiled linseed oil and a small piece of dryers; well sand-paper again, when this coat is dry. And now for the finis.h.i.+ng coat of color, which should be flat, _i. e._, mixed with turpentine and a few drops of j.a.panner's gold-size, but no oil. The dross black should be first ground in turpentine and the gold-size added after. When this has dried, varnish with hard drying oak varnish, leave for a day or two, and then rub down with pumice-stone powder, sifted through muslin; use a piece of cloth or felt wrapped on a small block of wood, and first wet the surface to be rubbed with water; dry with a wash-leather, and re-varnish. The ornaments are usually done with stencil patterns, and the lines are done with straight edges and lining fitches. Stencil patterns can be cut out of card paper. Before using, give a coat or two of patent knotting. For gilding panels, give a coat of buff first, then a coat of gold-size, in oil. When this has dried just sticky, press the gold leaf upon it with a ball of wadding, and leave for five or six hours, then rub over with a piece of soft wadding, and wash well with a sponge and cold water. The gold will not need any preparation before painting on, but if varnished afterward use pale varnish. Screens should be painted in colors to match the rooms they are intended to be used in. Birds, flowers and animals are the subjects generally introduced for this purpose. Birds should be painted toward the top of the screen, animals, flowers, etc., in the centre or at the bottom.

GLOSS PRINTING.

Gloss printing is done in two ways; one by using the gloss inks specially prepared for the purpose, the other by printing the gloss preparation on over the finished job, or over that portion of it required to be glossed.

To the inexperienced this is a difficult operation, attended by many failures. It is accomplished as follows:--Prepare a tint block the exact size and shape to cover the printing to be glossed. The block should be of boxwood or hard metal--soft metal will not do. Fix it on the press and make it ready as for ordinary work, with a good, even impression. Wash up the ink table, the rollers and the block itself thoroughly, removing the least trace of ink. Replace the rollers and distributors. Now, with a clean palette knife put a little of the gloss preparation on the ink cylinder or table, let it distribute for about a minute, and then pull an impression; if it comes up perfectly clean, the work may proceed, but if there are any signs of dirt, it is best to wash up again at once. While working the gloss, keep the machine in motion, and should the gloss become too sticky (which it is apt to do) sprinkle a very little turpentine on the rollers. It is best to have a separate hand to put on the gloss, so as not to delay the feeder, and the sheets should be taken away at once and laid out singly to dry. The two most important points are to have the machine clean and keep it in motion. After printing, wash up the gloss quickly with benzine.

TO BLEACH SHEEPSKIN PARCHMENT WHITE.

To bleach sheepskin parchment white, expose the pieces to strong sunlight under gla.s.s, in a moist atmosphere.