Damascus,
Here's what I found. Any suggestions for modifications for use on stocks? Linseed, Tung or Walnut oil?
Copal Varnish For Fine: Paintings, etc
Fuse eight pounds of the very cleanest pale African gum copal, and, when completely run fluid, pour in two gallons of hot oil; let it boil until it will string very strong; and in about fifteen minutes, or while it is yet very hot, pour in three gallons of turpentine, got from the top of a cistern. Perhaps during the mixing a considerable quantity of the turpentine will escape, but the varnish will be so much the brighter, transparent, and fluid; and will work freer, dry quickly, and be very solid and durable when dry. After the varnish has been strained, it" it is found too thick, before it is quite cold, heal as much turpentine and mix with it as will bring it to a proper consistence.
Read more:
http://chestofbooks.com/home-improvement...I#ixzz2tJPPaLAZThanks
Ken