The operator, having stocked himself with the above tools, may now proceed to lay the gold-leaf upon the work he desires to gild. There are two methods of doing this, known in the trade as "Oil-gilding" and "Water-gilding;" and so called from the composition of the size which serves as a vehicle for making the gold-leaf adhere to the work.
The following is the usual process in oil-gilding:—This method costs less and will wear much better than water-gilding, which will be presently described; but has not its delicate appearance and finish, nor can it be burnished or brightened up. Though the oil gold-size can always be purchased of good quality, it may be well to describe the fat oil of which it is principally composed.
Linseed oil, in any quantity, is exposed during the summer in the open air, but as much away from dust as possible, for about two months, during which time it must be often stirred, and it will become as thick as treacle. It is a good practice to pour into the pot a quantity of water, so that the oil may be lifted from the bottom of it, as all the impurities of the oil sink into the water, and do not again mix when it is stirred. When of the consistency above mentioned, the oil is separated from the water, and being put into a bottle, is subjected to heat till it becomes fluid again, when all remaining impurities will sink, and the oil, being carefully poured off from the sediment, forms what is termed "fat oil." The gilder commences by priming the work, should it not have been painted, using for the purpose a small portion of yellow ochre and vermilion, mixed with drying oil. When this is quite dry, a coat of the oil gold size, compounded with the fat oil just described, japanner's gold-size, and yellow ochre, is laid on, and when this is perfectly dry, a second should be given, or even a third. A superior finish is produced by going over the work, before using the size, with Dutch rushes or fish-skin, which gives a finer surface to it. After the last coat of size is applied, the work must be left for about a day, to set, taking care to keep it from dust; and the proper state for receiving the gold-leaf is known by touching the size with the finger, when it should be just "tacky," that is adhesive, without leaving the ground on which it has been laid.
The gilder then, taking on his left hand his cushion, transfers to it the gold-leaves from the books in which they are purchased. This is not very easy to a beginner, as the gold cannot be touched except by the knife. Gilders manage it by breathing under the leaf in the direction it is desired to send it, and flatten it on the cushion by the same gentle blowing or breathing. It is now cut to the required shape, and applied to the sized surfaces by means of the tip, which, if drawn across the hair or face each time it is used, will slightly adhere to the gold. The whole leaves are sometimes transferred from the books to the work at once; and when there is much flat space, it facilitates the process. As the leaves are laid on the size, they are pressed gently down with the cotton ball, or in sunken parts with camel-hair brushes; and when perfectly dry, the loose leaf is removed by gently brushing over the work with the softener, when if there should be found any places ungilt, such spots are touched with japanners' gold-size, and the leaf applied as before. The process of oil-gilding is then complete.
Water or burnish-gilding differs from the former in the use of parchment instead of oil size, and has received its name from being moistened with water in rendering the size adhesive, and also from its fitness for burnishing. Its superior beauty, however, is balanced by its being less durable than oil-gilding, and, unlike the latter, unfit to be exposed to damp air; it is therefore only used for indoor work or ornamentation. The parchment size is made by boiling down slips of parchment or cuttings of glovers' leather, till a strong jelly be formed, the proportions being one pound of cuttings to six quarts of water, which must be boiled till it shrinks to two quarts. While hot, the liquid should be strained through flannel; and when cold, the jelly required will be fit for use.
The work to be gilded will require several coats of composition: the first, or priming coat, is made of size thinned with water, and a little whiting; with this the work is brushed over, using a thicker mixture when there are defects which need to be stopped. Successive coats are then laid on to the number of seven or eight, and the last, being moistened with water, is worked over and smoothed on the plain parts with Dutch rushes. After this is completed, a coating is laid on, composed of bol ammoniac 1 pound, black lead 2 ounces, ground up on the stone with 2 ounces of olive oil. This is one out of many receipts; all, however, are diluted for use with parchment size warmed up with two-thirds water, and forming what is called water gold-size. Two coats of this should be laid on; the part about to be burnished should then be again rubbed with a soft cloth till quite even, and care taken that each coat be perfectly dry before the subsequent one be laid on. The work is now moistened in successive portions with a camel-hair brush and water, and while moist covered with gold-leaf in precisely the same manner as described in the directions for oil-gilding, great caution being observed in order to avoid wetting the leaf already laid down, as a discoloration would be the result. The work is now left for about four-and-twenty hours, when the parts which are to be burnished may be tried in two or three places. Care should be taken not to let the work get too dry, as in that case it would require more burnishing, and yet not give a good result. This state is known by its polishing slowly, and if it be too wet it will peel off; but should the places where the trials are made all polish quickly and evenly, the work may then be finished; for which purpose agates cut in proper forms and set into handles, are sold at the artists' colour-shops.[[121]]
The gilding satisfactorily accomplished, the artist or amateur has only to add the finishing tints and touches to his work, and then either to leave it alone, or to varnish it in accordance with the directions which will be given presently. If the work has been executed on canvass, it will remain only to apply it to the surface for which it may have been destined. This may be done by painting that surface with thick white lead, in two or three coats, and by also similarly painting the back of the canvass. The latter being then pressed evenly down upon the former, while the white lead upon both is still tacky, and, left for a few days, will be found to have attached itself with the greatest tenacity. Scrolls and panels cut out of zinc sheets may be painted upon just as though they were cut out of canvass, and may be fixed in their places by nails or screws. In illuminating on wood, pretty effects may be obtained by varnishing partially with transparent colours, such as the lakes, umber, Prussian blue, burnt sienna, &c., so as to allow the grain of the wood to show through,—restricting the use of opaque colour and gilding to a few brilliant points.
Distempering is a method of colouring walls and ceilings in which powder colour, ground up in water, and mixed with sufficient size to fix the colour, is used instead of paint made with oil. The most simple employment of distemper is in whitening ceilings, but it is also very much used in theatrical decoration and scene-painting; and rooms are sometimes so ornamented, the process being much less expensive than oil-painting. The foundation of all the colours is whiting, which, having been set to soak in water and break up of itself, is (when the top water is poured off) in a fit state for use; common double size is then added, with as much of the colour as will make the desired tint; but as this, when dry, will be many shades lighter than it appears when wet, trials should be made on paper, and dried by the fire till the colour required be attained. A gentle heat is required for melting the size. Old walls are prepared for distemper by being scraped and cleaned, and a coat of "clearcole" given to them. This is merely thin size and water with a little whiting: it serves to wash and smooth the walls and stop suction. Should there be any cracks or holes, a thick paste of size-water and whiting is laid in them with a palette-knife, and, when dry, smoothed down with pumice-stone, and another coat of clearcole given, when the wall is in a proper state to receive the ground tint; for new walls one coat of clearcole is sufficient. If it is intended to lay on lines of various colours, the wall is, previous to the laying on of the ground tint, set out as previously described; and the appropriate colours put on in succession, according to the design to be followed. All the colours required should be ground up, and kept ready prepared in galley-pots well covered over, so as to be at hand at once. The colour should be of the consistency of thick cream, and should run from the brush on being raised from the pot in one thread; if it run in several, it is too thin. If too thick, add more size and water; if too thin, more whiting. The pots used are the common red paint-pots.
VARNISHING.
Varnish is a solution of resin in oil or spirits of wine.[[122]]