Читать книгу A History of Inventions, Discoveries, and Origins (Vol. 1&2) - Johann Beckmann - Страница 16
ОглавлениеGOLD VARNISH.
As mankind could not have everything that they wished for of gold, they were contented with incrusting many articles with this precious metal. For that purpose the gold was beat into plates, with which the walls of apartments, dishes, and other vessels were covered. In early ages these plates were thick, so that gilding in this manner was very expensive38; but in process of time the expense was much lessened, because the art was discovered of making these gold plates thinner, and of laying them on with a size. Articles however ornamented in this manner were still costly, and the valuable metal was always lost. Yellow golden colours of all kinds were then tried; but these did not fully produce the required effect, as they wanted that splendour peculiar to metals, and appeared always languid and dull. It was not till modern times that artists conceived the idea of overlaying with silver, or some cheaper white metal, such things as they wished to have the appearance of gold, and then daubing them over with a yellow transparent varnish, in order to give to the white metal the colour of gold, and to the colour the splendour of metal. “When we cover our houses with gold,” says Seneca, “do we not show that we delight in deception? for we know that coarse wood is concealed under that gold39.”
This ingenious process, which at present is employed all over Europe in gilding wooden frames, coaches, and various articles, and which was formerly used in the preparation of the now old-fashioned leather tapestry, was invented towards the end of the 17th century. Anderson, in his Historical and chronological deduction of the Origin of Commerce, says that it was introduced into England by one Evelyn in the year 1633; and quotes, in support of this assertion, The Present State of England, printed in 1683.
This invention, however, does not belong to the English, but to the Italians, and properly to the Sicilians. Antonino Cento, an artist of Palermo, found out the gold varnish, and in the year 1680 published there an account of the method of preparing it. That work I have never seen; but I found this information in a book printed at Palermo in 1704, and entitled The Inventions of the Sicilians40. Among the few important things contained in this book, the greater part of which is compiled from old Latin writers, there is, in the additions, a receipt how to prepare the gold varnish (vernice d’oro). The whole account I shall transcribe, as the authors of the French Journal of Agriculture, Commerce, and the Arts, thought it worth their trouble to make it known in that work in 1778.
“Take shell-lac, and having freed it from the filth and bits of wood with which it is mixed, put it into a small linen bag, and wash it in pure water, till the water no longer becomes red; then take it from the bag and suffer it to dry. When it is perfectly dry, pound it very fine; because the finer it is pounded the more readily will it dissolve. Then take four parts of spirit of wine, and one of the lac, reduced, as before directed, to an impalpable powder, so that for every four pounds of spirit you may have one of lac: mix these together, and, having put them into an alembic, graduate the fire so that the lac may dissolve in the spirit. When dissolved, strain the whole through a strong piece of linen cloth; throw away what remains in the cloth, as of no use, and preserve the liquor in a glass bottle closely corked. This is the gold varnish which may be employed for gilding any kind of wood.
“When you wish to use it, you must, in order that the work may be done with more smoothness, employ a brush made of the tail of a certain quadruped called the vari, well-known to those who sell colours for painting; and with this instrument dipped in the liquor wash gently over, three times, the wood which has been silvered. You must, however, remember every time you pass the brush over the wood to let it dry; and thus your work will be extremely beautiful, and have a resemblance to the finest gold.”
After this invention was made known, it was not difficult to vary, by several methods, the manner of preparing it. Different receipts, therefore, have for that purpose been given in a number of books, such as Croker’s Painter, and others: and, on this account, young artists are frequently at a loss which to choose; and when a receipt is found better than another, experienced artists keep it always secret.
With the preparation of that varnish used for gilding leather tapestry Reaumur was acquainted, and from his papers it was made known by Fougeroux de Bondaroy. The method of making the English varnish was communicated by Scarlet to Hellot, in the year 1720; and by Graham to Du Fay, in 1738. In the year 1761, Hellot gave the receipt to the Academy of Sciences at Paris, who published it in their memoirs for that year.
If it be true, as Fougeroux says, that gilded tapestry was made above two hundred years ago, it might be worth the little trouble that such an examination would require to investigate the method used to gild it.
