We will now proceed in earnest to the serious work of gilding a picture frame.
1.—Commence by weighing out one ounce and a half of glue or gelatine. Put this into a cup and pour over it eight ounces of water by measurement. This of course you will do with the aid of your graduated glass measure. Let the glue soak for several hours, and then set the cup in a pan of water and expose it to heat until the glue becomes perfectly fluid and completely melted. A teaspoonful of carbolic acid must now be stirred into it and thoroughly incorporated with it. The acid will preserve it, as already stated, from decomposition, and most effectually so and for any length of time. This glue should be strained before being used. Whenever a portion of it will be required for the preparations herein described, it is well to take out as much only as may be wanted for use, leaving the balance untouched; as by so doing its purity can be relied upon, and besides, the oftener glue is melted the weaker it becomes.
2.—Lay down the frame which is to be gilded, back up, and, with a pencil, mark a line across the sections, if there be any, so as to be enabled to return them to their correct positions when ready to do so. Next, draw out the nails which fasten the sections together, and then take them apart. Now turn the sections face up and proceed to fill up any nail-holes about the corners, where the sides have been joined together, as well as all imperfections which may be found to exist. There are often fractures and indentations to be found, and these must be carefully repaired and the frame, or its several parts, made as perfect as can be. The joining at the corner must be filled up and made to appear solid.
3.—The preparation with which all this is to be done is made as follows:
Mix some of the Paris white with just sufficient water to moisten it thoroughly, and then add enough of the glue which has been described, and which has been melted for the purpose, to make the mixture into a thick paste. The Paris white might be mixed at once with the glue, but it does not seem to combine so well as when it has been previously moistened with water. It will be too lumpy and full of undissolved particles, unless mixed with the fingers; which operation would be generally objectionable. The paste should be just thick enough not to run.
4.—Now proceed to fill up the nail-holes, corner joints and all other visible imperfections with this mixture; either by applying it with a small bristle brush and laying on a sufficient quantity, until the required places are fully stopped up, and, when perfectly dry, sand-papering them down smooth and uniform, or by applying it like putty, with the fingers. The latter method is not recommended, as it requires a peculiar facility in the management, which can only be acquired by considerable practice, and besides, it does not give as good results.
5.—After smoothing down the fillings-up, the flats and hollows of the frame should be gone over first with number 0 sand-paper, and afterwards with a moistened rag, and be rubbed perfectly smooth and even and until the surface appears polished.
6.—The frame will now be ready for the white coat, which must be prepared in the following manner and then applied to the composition parts only:
Soak some of the pipe clay in water, barely enough of the latter to moisten the clay thoroughly, and then add enough of the glue, already prepared and in so hot a state as to render it of the consistency of thin cream; and add also a teaspoonful of the ox-gall, to prevent pin-holes forming and to keep it from frothing. A little practice will be required to determine invariably the requisite consistency, but the above directions will give a satisfactory result. The object of these two preliminary white coats is to kill any grease which may still adhere to the moulding, and which would otherwise prevent the proper drying of the oil-size. They also serve to give a soft and smooth appearance to these parts. The mixture as described must be applied warm, with a bristle brush (number 4 will do for the purpose), to all the composition parts of the frame. Apply this mixture sparingly, but sufficiently to cover the parts completely, and be careful to avoid bubbles while applying it. When the first coat is perfectly dry, apply the second.
7.—When the last white coat is perfectly dry, two coats of clear size should be applied all over these portions which are to receive a coat of oil-size. Even where a portion of the composition is to be burnished, (which process is done in water,) it is better to go all over these parts with the clear size; but the hollows and flats which should be burnished must not be touched, if it be possible to avoid doing so.