The Instant the Smoke changes from white to black, take off the Ladle; or the whole will break out into a violent Flame, and be spoiled or lost.
(Care must be taken that no Water be added: a few Drops only of which, woud—on Account of its superior specific Gravity, for the Cochuc swims in Water—make it boil over furiously, with great Noise.)
At this Period of the Process; two Pounds, or one Quart of the best drying-oil, (or even of raw Linseed-Oil, which, together with a few Drops of Neat’s-Foot-Oil, must have stood a Month, or not so long, on a Lump of Quick-Lime, to make it more or less drying)—being poured off the Lime-Lees; is to be put into the melted Cochuc, and stirred till hot: and the whole poured into a glazed Vessel, throu’ a coarse Gauze, or fine Sieve.
When settled and clear, which will be in a few Minutes; it is fit for Use, either hot or cold.
The Silk shoud be stretched all Ways horizontally, by Pins or Tenter-Hooks, on Frames; which Frames, the greater they are in Length, the better: and the Varnish poured on cold, in hot Weather; and hot, in cold Weather.
It is perhaps best, always to lay it on, when cold.
The Art of laying it on properly, consists in making no intestine Motion in the Varnish, which woud create minute Bubbles. Therefore Brushes of every Kind are improper.
Each Bubble breaks in drying, and forms a small Hole, throu’ which the Air will transpire.
