Scientific American 4, 26.7.1862
Painting Glass Transparencies. - Provide a small muller and a piece of thick ground glass five or six inches square to grind the colors on, also a small pallet knife and a few bottles to put the colors in. For a red color get a little scarlet lake, and for blues a little Prussian blue. For green use purified verdigris ground with a quarter of its bulk of gamboge, and for brown use burnt umber, and for black, burnt sienna black. These colors are truly transparent. Having all these colors ready, grind them in the balsam of fir mixed with half its bulk of turpentine; mastic varnish will do very well, but the balsam is the most beautiful. To coat the glass black the painting, dissolve asphaltum in turpentine and mix with lampblack.
Varnish for Wood Patterns. - The most simple varnish, combined with adaption, is the following: - 1 quart of alcohol and a quarter of a pound of gum schellac. This put into a bottle and when wanted for use mix up with a little lampblack to about the thickness of cream and varnish the pattern over, rubbing it into the grain of the wood, until a slight friction produces a polish. This varnish makes a smooth surface on the pattern, rendering it more easily drawn from the sand, and it fills up all pores or worm holes that may be in the wood, consequently a cleaner and smoother casting is produces.