This section is from the book "A Treatise On Architecture And Building Construction Vol4: Plumbing And Gas-Fitting, Heating And Ventilation, Painting And Decorating, Estimating And Calculating Quantities", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
154. Assuming that the student has, by this time, acquired some knowledge of the painter's art and of the tools required by this form of work, demanding, as it does, attention, practice, patience, and cleanliness, there are, we need scarcely say, many ways of gilding. To one especially, known as oil gilding, we invite the student's attention.
The process of oil gilding is employed to beautify the interiors of private dwellings and of public buildings; all interior work is, in fact, usually oil gilt. This method is the most commonly selected on account of its recognized wearing qualities. Fat linseed oil is, for this purpose, used, mixed with finely ground yellow ocher, the older the oil the better.
The gilder's tools should be in the best of order, his cutting knife (Fig. 51) scrupulously clean, as likewise his cushion, as shown in Fig. 52, which, when worn, should be recovered with soft chamois leather.
The gold leaf is spread on the cushion and cut into small squares or rectangles with the knife; a thin, flat brush called a tip, as shown in Fig. 53, is then used to lift the leaf from the cushion and place it upon the surface to be gilded. The tip is first drawn across the hair or face in order to slightly moisten it so that the leaf will adhere until transferred to the sized surface.
Important, also, is it that there be provided a proper platform, from which the whole ceiling-may with ease be worked upon. There should also be a substantial bench or stand, such as shown in Fig. 54, placed in the middle of the room, for colors and thinnings and such mixing of tints as may be required.
Gilding is finished in two ways: burnished bright or left dead. The latter is the most usual style of decoration adopted.
155. Besides oil gilding, there is the Japan method of gilding, and water gilding, used for frames, mirrors, and console tables. Ceiling work is usually executed in oil, but may be done, wholly or in part, in Japan gilding.
Oil gilding is durable, rich, and brilliant, but Japan gilding is the more expeditious, for, as the work is not liable to bloom, or become clouded and discolored on the surface after drying, there is no necessity to size it after completion, as is the case with oil gilding. Japan being the best vehicle for running the lines in a design, may also be preferred for such parts as do not present a solid or rounded surface. Japan gold size is, when used alone, too rapid a drier to insure the requisite tack or adhesiveness; most gilders, therefore, add a proportion of copal varnish and a drop or two of linseed oil.
In case the lines are to be run upon a dark surface color, or in juxtaposition thereto, the vehicle should be slightly stained by the addition of some finely ground chrome. If, however, the lines are to be run in contrast with light tints, a portion of burnt sienna should be added, care being taken that the pigment thus used is sufficient only to give requisite staining property, without affecting the adhesiveness of the gold size. The medium thus prepared, lines may with it be run by the aid of straightedge and lining fitch. Moldings, also, may be gold sized with sable or fitch. Stenciling, too, may be done, and such parts as require penciling in by hand, readily completed.
Japan size, if properly manipulated,. should be ready for gilding in from one to two hours, and should, after being thus ready, hold the tack for at least an hour.
Oil size, from its liability to spread and form a ragged edge on the work, is not adapted to lining or to stenciling. Where the paint underneath is not properly hardened, the surface should, before gilding, be brushed over with white of egg and dusted with powdered whiting. This process, which arrests the adhesiveness of the paint, is unnecessary if the colors have been worked in flatting, provided the flatting itself has been properly made up.
156. Oil gold size being an expensive commodity, many gilders make their own, as being more reliable than any of the readily purchasable kinds. It is simply a preparation of fat or linseed oil, thickened by age or exposure to the sun. For this purpose the oil which collects on the top of oil paint should, after standing a few weeks, be carefully poured into another vessel. Mixed with raw linseed oil, this is placed in a large, wide-mouthed pot, covered with a sheet of glass, to keep out dust particles. This is, in turn, put where it may, for two or three months, get the direct rays of the sun, during which time it must be occasionally stirred. If water be placed at the base of the pot, such impurities as may be in the oil will sink through the water to the bottom, greatly facilitating this stage of preparation. The oil, under this treatment, will, in the course of a few weeks, attain the consistency of syrup and may be poured off into bottles.
This, again, should be heated gently until the oil once more becomes fluid, when it may be gently strained through coarse muslin, to remove the sediment, after which it is put into gallipots or covered away for use. When required for use, a proportion of yellow ocher and chrome finely ground should be added to the oil, which, if found too slow in drying, may be further implemented by a slight admixture of the better class of carriage varnish. The usual time required for it to set properly on the surface, is from twelve to sixteen hours. Properly made, it will, after it has become set, hold the tack for six .or eight hours or even longer.
Turpentine should never be added to either oil or Japan gold size, as its evaporation greatly impairs the brilliancy of the gold, some work actually turning black in consequence of the use of turpentine as thinning. The best method is to thin out with oil or varnish. Oil gold size invariably tends, however, from its very nature, to produce a ropy surface, i. e., a surface streaked with lines of uneven thickness or body. Hence, on broad surfaces, to insure an even spreading of the vehicle, it must be carefully laid off.