Valuable Secrets concerning Arts and Trades:
or Approved Directions, from the best Artists, for the Various Methods...
Printed by Thomas Hubbard,
Norwich, 1795Chap. III. Secrets for the composition of Varnishes, &c.
1. Take two pounds of double-rectified spirit of wine; seed-lac, four ounces; sandarac, as much; gum copal, one. Set all a-dissolving, on hot ashes, in a matrass, or a vessel with a long neck. When perfectly dissolved, strain it through a jelly-bag, made of new cloth. Mix, with that which shall have strained out of the bag, out spoonful, of oil of turpentine; then bottle and stop it well, and set it in the sun. There will happen a separation, and a certain coarser part will shew itself at the bottom, while another more clear will appear swimming on the top. Divide carefully, by inclination, the clearest from the thickest part.
2. This last you may use with fine lamp-black, well picked, and free from all sorts of hard nobs, to make a black-colour varnish. With it, you rub whatever you want to be varnished, and lay, one, two, or three coats of it, more or less, according as you think proper, letting dry between each coat. And, when this is done, you put, of the first separated clear part of your varnish, as much as you find requisite to give your work a fine lustre.
N. B. It is proper there should be some fire, so near to the work, as it may receive from it some gentle heat, while all this is performing: and when the whole is well executed, you must let dry in the shade what is varnished, and guard it against the dust.
3. If, instead of black, you want a red colour, you must, from the very beginning of the operation, join some tacamahaca-gum with the spirit of wine of double rectification above mentioned; and, in lieu of lamp black, in the second part of the operation, you put some cinnabar in powder. Then, when you have done with laying the several coats of varnish, in which the cinnabar is, you put in the clear varnish, which is deflined to make the last coats, for lustring, some dragon's blood in tears.
4. You may put, in the same manner, whitening in varnish, if you want it white; or verdigrise if you want it green; and so on any other colour you want it to be, proceeding, in respect to each of them, as before directed for the others.
N. B. These varnishes, when dry, do all require to be polished. For that purpose, you take a cloth, dip it in tripoly, and rub, with moderation, over the last coat of varnish, till you find it has acquired a sufficient degree of lustre, and equality.
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