“First, if you would paint miniatures you must draw with a leaden style figures, foliage, letters, or whatever you please, on parchment, that is to say, in books: then with a pen you must make the delicate permanent [p166] outline of what you have designed. Then you must have a paint that is a sort of gesso, called asiso, and it is made in this manner; namely, a little gesso sottile [see chap. 116, below], and a little biacca [whitelead], never more of this than equals a third part of the gesso; then take a little candy, less than the biacca; grind these ingredients very finely with clear water, collect them together, and let them dry without sun. When you wish to use some to put on gold, cut off a piece as large as you have need of, and temper it with the white of an egg, well beaten, as I have taught you. [The froth is allowed to stand for one night to clear itself.] Temper this mixture with it; let it dry; then take your gold, and either breathing on it or not, as you please, you can put it on; and the gold being laid on, take the tooth or burnishing-stone and burnish it, but hold under the parchment a firm tablet of good wood, very smooth. And you must know that you may write letters with a pen and this asiso, or lay a ground of it, or whatever you please—it is most excellent. But before you lay the gold on it, see whether it is needful to scrape or level it with the point of a knife, or clean it in any way, for your brush sometimes puts more on in one place than in another. Always beware of this.”
“Chap. 116.—How to prepare gesso sottile (slaked plaster of Paris) for grounding panels.
“You must now prepare a plaster for fine grounds, called gesso sottile. This is made from the same plaster [plaster of Paris] as the last, but it must be well purified (purgata), and kept moist in a large tub for at least a month; renew the water every day until it almost rots, and is completely slaked, and all fiery heat goes out of it, and it becomes as soft as silk. Throw away the water, make it into cakes, and let it dry; and this gesso is sold by the druggists to our painters. It is used for grounding, for gilding, for working in relief, and other fine works.” [p167]
APPENDIX: ON GILDING
(By Graily Hewitt)
Success with raised gilding can only be expected when practice has rendered attention to the details of the process automatic and there is no need to pause and think. Even then the results must be somewhat uncertain and experimental. For our own preparations of size are usually unsatisfactory, and the ingredients of the best we can buy are unknown to us. And our vellum is certainly not of the quality we find in the old books. Some one is badly wanted to investigate the chemistry of the one and an appropriate preparation of the other. But we can take as much care as our time allows, passing nothing as “good enough” which we have not well examined, and bringing to the business all the patience and deftness available.
Vellum is too stiff, or too dry, or too greasy. When stiff, it is too thick for books; when dry, too apt to crack or cockle; when too greasy, exasperating. And yet the soft and rather greasy sort can be rendered more agreeable than the rest with labour. It should be rubbed by the flat of the hand with powdered pumice (or even fine sandpaper on the rough side) and French chalk, especially on its split (or rougher) side, until it is serviceable. A few trials will teach how long to give to this. Five minutes for one side of a lamb’s skin would not be too much. It can then be beaten with a silk handkerchief, but not rubbed with this until the size has been laid. It may be rubbed cleaner between the laying of the size and the gilding. Especially must those parts of pages be thoroughly rubbed clean which in the book, when made up, will lie upon and be pressed against gold letters on the page opposite; or the pumice left behind will scratch them. On the other hand, if the vellum has not been thoroughly pumiced on both pages, the greasiness in [p168] it will dim the gold in time, both from above and below; or even make the size flake off altogether. The size is often blamed for faults of the vellum and its want of preparation.
Again size, or “raising preparation,” is too sticky or too dry. If the former, the gold will not burnish well; if the latter, it will burnish, but will not stick at the edges, and will crack sooner or later. And though the essential quality of gilding is brightness, one may be content to fail of this rather than have letters ragged in outline or broken on the surface.
The size in use should be just liquid enough to flow evenly from the pen. More water makes it dry too brittle, and tends to cockle the vellum also; less tends to blobbiness and unevenness. Even when it is put on fairly an uncomfortable groove is apt to form as it dries down the centre of letters; but this can be either filled up as soon as the first layer is dryish, or the sides of the groove can be scraped (when the letter is quite dry) down to the level of the groove itself with a sharp knife. The knife must be sharp. As this scraping does not affect the extreme edges the power of the size there to hold the leaf is not impaired by it; and certainly a well-scraped surface is extremely even and pleasant to gild. If the surface, however, be burnished and not scraped before laying the leaf, it will not hold the size well, and remains lumpy also where lumps were there originally; while scraping gets rid of these. During use the size should be kept thoroughly mixed; and a small sable brush serves well for this purpose, as soon as it can be used so carefully as not to cause bubbles.
To know the exact time to allow between laying and gilding one had need to be a meteorologist, so much “depends on the weather.” Very dry and very wet weather are equally unkind. Generally an interval of about twenty-four hours is right; but it is better to gild too soon than too late, provided one can be content, on testing the naked surface of the gilded letter with a [p169] burnisher, and noting that the glitter is reluctant to come, to leave the burnishing for a while, and only lay the leaf, pressing it well home to the outline of the letters. The burnishing can then be done in a few more hours. But if the size be too dry, the difficulty will be to make the leaf stick to it at all. In this case the leaf adhering can be scraped off, the size scraped down further, and another thin coat added and gilded after a shorter interval. If the letter be so fouled that such repairs are difficult, it should be entirely scraped away and the size relaid altogether. In doing this care is needed that the vellum be not injured round the letter.
The best gold-leaf for ordinary work costs about 3s. for twenty-five pages. More expensive leaf, being thicker, does not stick so well to the edges; cheaper is too thin to burnish well. Two kinds may be used together with good results, the finer leaf being put on next the size, and the thicker at once on to the top of that. The letter is then pressed and outlined as usual through paper, and the thin leaf will be found of considerable assistance towards the making of a clean cut edge. Generally, however, the piling on of several leaves is inadvisable, as bits are liable to flake away as the letter goes on drying, leaving dim specks where they have been. Yet if, after the outlining through the paper, the leaf is seen to be very dull or speckled with the colour of the size, this means that the size has been partly pressed through the leaf; and another laid immediately will have enough to stick to, and will burnish well. The best result comes of one moderately thick leaf laid and burnished at the right time as quickly as possible. Thicker leaves need only be used for large surfaces, where the edge can be scraped even and clean, or where a black outline is to be added.