The various methods of applying gold leaf used by painters and decorators are termed: Oil gilding, Japan gilding, and Water gilding.

These methods vary in detail upon different kinds of grounds. Oil or Japan gilding is used upon painted surfaces, or grounds that have been strongly sized or varnished.

Oil Gold Size

Oil gold size is a preparation of fat linseed-oil, which has, by exposure to the atmosphere, lost its power of absorbing oxygen, and become viscid and less hard drying, it may be prepared by exposing linseed oil to the air and light in a wide, open-mouthed vessel for about six months. To make it usable and give it a little body and color, ochre is ground up in about one-third of the whole quantity and added to the whole bulk, a little driers, usually litharge, is also required, and, if too thick for use, it must be thinned to proper consistency with boiled oil. A small quantity of good varnish, one part to twenty, added to gold size, gives it hardness and additional luster. Good oil size will be ready to receive the gold at any time between twenty-four hours and a week from the moment of using it, and the longer it holds its tackiness the better is the result, provided that the size ultimately dries firm and hard, like a piece of gold-beater's skin.

Japanners' Gold Size is a quick varnish drying in about half-an-hour to two hours, and is ready for gilding as soon as sufficiently dry. It must be gilded upon at once when this is the case, as the tack soon changes into a hard varnish surface.

Gilding can be done with varnish, but the excessive gloss gives a blackish look to the gold, and as the varnish hardens it loses its hold of the metal, which will then wash off with soap and water. Notwithstanding this fact, it is often used in large proportions added to gold size by certain decorators, who admire the additional gloss, but do not trouble about durability.

Many special sizes of a varnish nature are made for sign writers.

Water Gold Sizes vary in their nature for different purposes. For gilding on prepared wood, papier mache, plaster, or composition, as for picture frames, two kinds are used, burnish and matt gold size.

Burnish Gold Size is made from pipeclay and black lead, with a small quantity of mutton suet added in the grinding. It can be purchased ready made, and is used with ordinary parchment or gelatine size as a binding medium. Gilding on this size will take a good polish, or burnish with an agate burnisher.

Matt Gold Size

Matt size is for gold which is required to have a matt or dead surface, and is made from pipeclay, Armenian bole, and other materials. It can be purchased ready for mixing with the clear parchment or jelly size.

Isinglass Gold Size

Gilding upon glass is done with isinglass size. Take a pinch of best Russian isinglass, put it into a pint of water, and stand the whole in a covered jar in the oven for a few hours, when dissolved or cooked add a 1/4 pint of spirits of wine and strain or filter through white filter paper. The spirits of wine removes the solid or waste portion of the isinglass, and also serves to counteract grease on the glass, or in the hairs of the brushes used, its action is similar to that of wine in milk.

Clear Size For Gold

Gold is often clear sized to improve its color and prevent blooming. This size, as well as that used for matt and burnish work, is best prepared from finest gelatine, or from boiled parchment cuttings.