Secrets of Glass Manufactory - Compositions to Imitate Precious Stones, called French Paste

Secrets Concerning Colors and Painting
§ I.  Paint In Varnish On Wood
§ 2. Paint On Paper
§ 3. Compositions For Limners
§ 4. Make Transparent Color
§ 5. Compositions to Dye Leather
§ 6. Color or Varnish Copperplate Prints
§ 7. For Painting on Glass
§ 8. Color Preparation for Oil, Water, and Crayon
       Marble and Jasper Paper
       Methods to Clean Paintings
       Making Good Crayons
       Directions for Coloring Prints
       Directions for Painting in Oil
§ 9.  Preparation of Lapis Lazuli to Make Ultramarine

I.  The method of gilding with size, or oil.
    The gold leaves which are commonly used in gilding are of different sizes, as well as of various degrees of thickness.
    To gild on iron and other metals, the strongest and the purest are preferable.  That which is not so pure is commonly employed by carvers in wood, as it comes cheaper to them.
    We are indebted to this discovery of the secret in painting in oil, for the means of gilding in such a manner as to resist the injuries of the weather.  An art the ancients were no acquainted with, and they could not obtain from their method of applying gold, since they used nothing else but whites of eggs for gilding marble, and such other bodies as do not admit of being committed to the fire.  As for the wood, they made a composition which was used with size.  But neither size nor whites of eggs can resist the water.  Therefore they could not, with propriety, gild any other works than such as were sheltered from the intemperance of the weather, viz. their arches, their ceilings, which were all gilt in that manner.  The composition they used for gilding on wood was made of a slimy earth, which held the place of the sized white we use now-a-days, and with which gilders made that first coat, called by artists assiette, or burnish-gold size.

II.  To gild with size, or what is called in burnish gold.
    1. Begin by preparing your size as follows.  Take about a pound of odd bits of parchment, or leather, such as is prepared for gloves of breeches.  Put this a boiling in a pailful of water, till it is reduced to one half, and your size is done as it ought to be.
    2.  When you want to use it for wood which is to be gilt, it must be boiling hot, otherwise it would not penetrate sufficiently into the wood.  If you find it too strong, you may weaken it by adding water to it.  Then with a brush, lay the size in smooth, if it be a plain work; but if a carved one, you must lay it in stumping with the brush; either of which way is equally termed to size.
    3.  When the wood is thus prepared with size only, make another preparation, called an infusion of white, in the following manner;  Take a quantity of size boiling hot, as much as you think will be sufficient for your work.  Dilute a discretional quantity of pulverised whitening in it, and let it infuse some time.  When it seems well dissolved, strain it through a cloth to make it finer; then with a brush, as above, give seven or eight different coats of it in stumping on your work, and two more coats in smoothening, if it be on carved work; but if on a plain one, you must give a dozen coats at least; for the white is the nourishment of gold, and serves to preserve it a great while.  Be careful not to give coat upon coat, unless the last be very dry; otherwise the work might scale.  You must even have a great care that each coat should be laid on a perfectly equal as possible, both in the strength of the size, and thickness of the white, to avoid the same inconveniency.
    4.  When you have given the requisite number of coats, whether in stumping, or in smoothening, you must let the work dry thoroughly before you polish it.  As soon therefore as it is perfectly dry, you must have a coarse rough cloth, quite new, and as closely wove as possible, with little deal sticks, cut square, angular, or pecked, according as the nature and carving of the work require; and thrusting one of these sticks into the cloth, rub an smoothen the white.  Then taking a brush made of boar's bristles, which has been already used, because it is softer, dip it into some clean water, and wet the work in proportion as you go on in polishing, with your little sticks wrapped up in cloth.  This precaution completes the smoothening of the work, by leveling the small bumps and imperceptible undulations you may have made either in giving the white, or in polishing it.  For the smoother the work, the more easy to burnish the gold, after having been applied.  Wet and brush it in proportion as you polish it, with a brush a little worn, spare not to purge your brush of all the filth it gathers about the point of its hair, by washing and squeezing it again as soon as you seen them grow thick in the least with that dirt.
    5.  When the white is once more dried, rub it with shavegrass, or rushes, in order to level still better all the grains and inequalities which may be on it.  Do not, however, rub it too much with the shavegrass, because you may hereby fall from one error into another, and make your white what is called greasy or smeary, which would prevent it afterwards from uniting with the burnish gold size, which is to precede the laying on of gold.
    6.  Now, as it is difficult that after ten or a dozen of coats of white, the carving should not be choked up, they who are fond of finishing their work highly, take an iron instrument, made on purpose, and curved by one end, (called by the French a fer-a-retirer,) with this raffling crook they go over all the turns, and open all the places which want it, to restore them to their former sharpness.  Or else, take what is called a fermoir, or gouge, and give to the ornaments the same form which the carver observed when he first cut them,  turning agreeably the sides of leaves according to nature; then bretelling with another instrument, called the veining crook (in French fermoir 'a nezrond,) all the ornaments, you thereby render neater, and more delicate than the carver had first made it.  That you may cut the white more neat, observe only to wet it a little with a brush.
    7.  When works are not of great consequence, you may easily save yourself all that trouble; principally if the carving is pretty neatly finished, by giving two or three coats only of white, very clear.  But the white is the principal support of gold, this operation is never so perfect as when it has received ten or twelve coats of white, and been afterwards re-cut, carved, veined and repaired over again, as I said before.
    8.  Then dilate some yellow ochre, and grind it with sized water, weaker by half than that which you used for the whitening.  And having made it a little fluid and warm, lay one coat of it over all the work, principally in such deep places of the carving as you cannot come at to lay the gold leaf, that this colour may supply its want.
    9.  When the yellow is dry, lay over it (in all the raised places, but not in the bottom grounds) three different coats of another sort of composition, called in French assiette, and here, burnished gold size, prepared in the following manner;  Bol armenian, about the bigness of a nut, and grind it by itself; bloodstone, or red chalk,  the bulk of a horse bean, and black lead pulverised as big as a pea, grinded both together; and at last one drop or two of tallow, which grind afterwards with all the other drugs and water, taking them a little at a time, to grind and incorporate them the better.  Put this composition in a cup, and pour over it some of your aforementioned size, boiling hot, and strained through a cloth,  Stir and mix all well, while you pour that size, that the whole may be well diluted.  The brush you lay it on with ought to be soft, and the first coat lay pretty thin; but as for the two others, they must be so thick that the stuff should run with difficulty from the brush.  Each coat must be well dried before giving the next.  And when the last is perfectly dry, take a stiffer brush, and dry rub the work all over, to smoother all the grains and little risings of the gold size, and thereby facilitate the burnishing.
    10.  The gilding is performed as follows.  Have first a pipkin very clean, in which put some very clean and filtered water, and a few wetting pencils, which ought to be make in the form of those ermine tails which hang in the ermine skins.-- Get nest a cushion, which is to be made with a light and flat square board covered with calf leather, fixed all round with nails, and stuffed underneath with cotton.  Let this cushion be also surrounded by the back part, and two thirds of each of the two sides, with a band of parchment of five ore six inches high, to prevent the air from blowing off the gold leaf.
    11.  Put what quantity of gold leaves you think proper.  With the gilding knife spread these leaves very smooth, in doing of which you will assist yourself very much if you breath over them while you pass the knife under.  Then cut it in as many parts and sizes as you want, or, if there be occasion for it whole, take it with your tip, and lay it.  A tip (in French, palette) is an instrument made with the point of a squirrel's tail placed upon a round stick flattened, and about half and inch wide by one end, with a slit, to separate and spread the better the squirrel's tail.  This tip pass along your cheek, and with it take of the gold leaf, or what part of it you have divided, and thus lay it on the work.  Previously, however, to this, you must have passed on the place one of your pencils immediately before the laying of the gold, otherwise the gold would be incessantly slitting and cracking.  As soon as the gold leaf is laid on the work, take your water pencil quite wet, and passing it above the work, let the water run from it under the leaf just applied; this will quickly make it spread and catch.  But if is should pass over the gold leaf, it would immediately spot and spoil it; and as it is impossible to lay on gold, especially when wet,  you would not be able to repair it, unless you take the gold leaf entirely off, and put another in the stead.  On the contrary, by the water slipping under the gold leaf just laid, you will find that this spreads infinitely more easy, and almost of itself; it sticks faster on the gold size, never scratches, is more easily dusted for burnishing, or matting with size; in short, the work looks infinitely better in every respect.  As it is impossible with all possible care, but there may happen some little accident now and then, principally in carved works, you must, in such case, cut some small bits of gold, which, with a pencil, take and put on the defective places, when you look your work over.
    12.  When the work is perfectly dry, burnish it where you think proper, in order to detach certain parts form the other, to make them set off and show to better advantage.  To that effect use an instrument called a burnisher, made either of a real wolf's tooth, or rather as they now use it, an agate made in the same form, and finely polished, or else a pebble called blood stone.  Before burnishing you must, with the crooked point of you burnisher, push down all the parts of gold in the hollow parts which you forgot to do with the pencil, the dust is with a large one.  When the work is burnished where you want it to be so, matt and repass, with a very soft pencil and burnish gold size, what has not been burnished, or, you may again put some vermilion, to raise the gold, and make it loot brighter; which is call, in term of art, repassing.
    13.  There is again another repassing you must not forget, which is to lay, in all the hollow places of a carved work, a coat of a composition of a vermilion, as I am going to prescribe, and which will give an incomparable fire to the gold, and make it look as goldsmith's work.  This composition is such--Grind together, on marble, some vermilion, gamboge, and oil of turpentine.  If, after having burnished, matted and repassed your work, you find again some defective places, you may mend them with gold in shell, which is diluted with a little arabic, and applied with a pencil.  This sort of faulting is no small addition to the beauty and richness of the work; the French call it buckling with gold in shell.

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