Preparation of Sizes for Gilding.

Scientific American 15, 9.10.1869

Gold Oil-color, or Size. - The English method of preparing the color in size, which serves as the ground on which the gold is laid, is, to grind together some red oxide of lead with the thickest drying oil that can be procured - the older the better. To make it work freely, it is mixed, before being used, with a little oil of turpentine, till it is brought to a proper consistence.

Gold Water Size. - One pound of Armenian bole, two ounces of red lead, and a sufficient portion of black lead, are ground separately in water, and then mixed, and re-ground with nearly a spoonful of olive oil. The gold size is tempered by mixing it in parchment size which is clear and clean, and has been passed through a fine sieve to clear it of all foreign matters. The parchment size is made by boiling fown pieces of white leather, or clippings of parchment, till they are reduced to a stiff jelly.

Preparatory Size. - Boil a handful of the leaves of wormwood and two or three hands of garlic in a quart of water, until the liquid is reduced to one half; then strain it through a cloth, and add half a handful of common salt, and nearly half a pint of vinegar. The design of this composition (usually employed in gilding looking-glass and picture frames) is to obviate the greasiness of the wood, and prepare it the better to receive the coats which are to be laid on, and to preserve it from the ravages of worms. When used, it is mixed with a sufficient portion of good glue, boiling hot. In applying it to the gilding of plaster or marble, the salt mus be left out of its composition; as, in damp situations, this would produce a white saline efflorescence on the surface of the gold.

White Coating. - A quart of strong parchent size and half a pint of water are to be made quite hot, and to this are to be added (in small portions from time to time) two good handfuls of commong whiting passed through a fine sieve; this mixture is to be left to infuse for half an hour, when it is to be stirred carefully so that the amalgamation may be perfect.

Coloring Yellow. - Half a pint of parchment size is taken, which must be clean, white, and clear, and of one half the strength of that used for the white coating; this is warmed, and there is mixed with it two ounces of yellow ocher, very finely ground in water; it is then left at rest, and the clear portion decated, which gives a fines yellow color, that serves, in water gilding, to cover those deep recesses into which the gold cannot be made to enter; it serves also as a mordant for the gold size.

- The Painter, Gilder, and Varnisher's Companion.

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