The thicker the Varnish, the sooner it dries.
To make thin Varnish.
327. Article 1. To make an excellent thin Varnish.
To one Quart of cold raw Linseed-Oil poured off from the Lees made by a Lump of unslacked Lime on which the Oil has stood, ten or eight Days, at the least, in order to communicate a drying Quality: (or on brown Umber burnt and pounded, which will have the like Effect:)—add half an Ounce of Litharge.
Boil them for half an Hour.
Then add half an Ounce of the Copal Varnish.
327. 2. While the Ingredients are on the Fire, in a Copper Vessel; put in one Ounce of Chio Turpentine, or common Rezin: and a few Drops of neat’s-foot-oil: and stir the whole with a Knife, or any clean Thing.
When cold, it is ready for Use.
327. 3. The Neat’s-Foot-Oil prevents the Varnish from being sticky, or adhèsive: and may be put into the Linseed-Oil, at the same Time with the Lime, or burnt Umber.
327. 4. To make the above Varnish transparent, or white; use Mastic and Copal: to make it brown, use Seed or Shell-Lac, and browner still, use pounded burnt Umber.