Re: Wood finishing
Well, first, rottenstone is very finely ground pumice (volcanic rock - highly aerated lava, actually) originally used for "French Polishing" in the cabinet trade. For more than you will ever probably want to know about French Polish, see this link:
http://www.lmii.com/CartTwo/FrenchPolish.htm
Second, re the various mixes of linseed, tung, etc.
I have used a formula, or actually, formulas of the above for about forty years, which somehow got named "juice" in the early days.
Juice I: 1/3 BLO, 1/3 Tung, 1/3 Gum Turpentine. This is a fairly "thin" solution with great penetrating qualities. Builds VERY slowly, about 4 hours between coats.
Juice II: 3/8 BLO, 1/2 Tung, 1/8 Gum Turpentine. Heavier bodied than Juice I, quicker build, kicks quicker, dries harder. This is my everyday, go to mix.
Juice III: "Cheater Juice." 3/8 BLO, 1/2 Tung, 1/8 Varathane. Varathane is compatible with both BLO and Tung, and Varathane's driers greatly accelerate the time it takes for a coat to kick off. Warning: if you don't stay on right on top of wiping this one down, it will turn into varnish on you and you will be digging out the sandpaper. Good for hard service.
Juice IV: "Butter Juice." 1/2 BLO, 3/8 Tung, 1/8 Gum Turpentine. Add 3-4 oz. Beeswax per quart. This is a very soft and creamy finish, great for furniture, not so great for hard service. I have a lot of older furniture which I have refinished with this.
As you might have guessed, there are damn near infinite variations on the above, depending on the species of wood being used and the service its being put to. But that is a book in itself.
Enjoy
isher
ps.
SAFETY NOTE. RAGS OR PAPER TOWELS USED WITH ANY OF THE ABOVE CAN SELF IGNITE IF NOT DISPOSED OF PROPERLY.