LXII. To imitate porphyry.LXIII. To imitate serpentine.

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.


LXII. To imitate porphyry.

Take English brown red. If too red, add a little umber, to it, or some soot. Pound all into powder. Then have a plank, or marble stone, of a fine polish, which, you overlay with oil. Make a colour composed of brown red, and a little flat, or Venetian lake, previously grinded with gum adragant. Then, with a largish brush, take of that colour, and asperse your oiled marble with it, by striking the handle of the brush on your wrist, as the book binders do to stain the covers of their books. When your marble shall have been thus well speckled all over with that red colour, you let it dry. Then, taking your lump of brown red and umber, you dilute it, make a thin paste of it, and lay it on your speckled marble. When this is also dry, it admits of a very fine polish, and looks like porphyry.


LXIII. To imitate serpentine.

1. Take auripigment, which you grind well first with water, and next with a little addition of indigo. Let this dry; and, when dry, reduce it to an impalpable powder; then mix it with a little gum adragant, and make a paste of it, as in the above receipt.

2. After this is done, take some lighter green, put a little more auripigment with the indigo, till you come to obtain the trus hue of the spots which are in the serpentine. Of this colour you take with a brush, and asperse with it a marble piece in the same manner exactly as described in the preceding article; and when this is dry, you lay your first prepared pastee on it. - For the rest, do as above.

N. B. You may thus, with a brush, imitate, or even invent, all sorts of marbles, according to your taste and fancy; and, when the first laid colours are dry, lay your paste over them, let them dry likewise, and polish. For , have several different colours prepared as above; asperse, or mark with each of them separately, and one after another, on some piece of glass, or well polished marble. Then make a paste and lay it over them, of whatever colour you will. If you will have it white, it is done with whitening, or white-chalk, and a little mixture of yellow ocher. These sorts of works admit of being overlaid with an exsiccative varnish.