david weaver
Thanks for the comments, John. When I looked up asphaltum on ebay yesterday, there were many options color wise - maybe 5? Depending on where in the world the powder was coming from.

I stuck with black, but thought the others were neat looking. They don't appear to be intended for paint purposes, though (some of them were mixed with herbs), so I wasn't brave enough to buy them and find out that they're not good. I stuck with black gilsonite. I should've bought it from kremer pigments, but didn't think about them at the time.

I read a little bit about japan drier yesterday. Everything i read from folks is "too unhealthy to use, extremely toxic. Generally mineral salts that are some kind of cobalt (or cobalt salts?). Not a geologist or chemist, so no clue about the accuracy of that statement. I think my varnish is probably a "healthy varnish", but it would probably take years to fully cure. it takes a few months and a couple of sun sessions for it to be reasonably hard, but it's still not resistant to shellac when I use shellac to touch up any bumps a guitar gets when installing the hardware.

At any rate, I got a chuckle out of the insistence from some posts to not use japan drier (because of the toxicity of cobalt) and then subsequent recommendations to use something like epifanes. I have epifanes on hand, too, but it smells like an oil slick and is really sticky (the turp/pine/damar varnish is sticky, but less so, and easier to wash off or wipe off with some effort). Epifanes dries a little bit faster, and sure enough, the MSDS lists cobalt.

So I'm going to try some in mine. George recommended the same if I was getting impatient, but he said a drop at a time, as things can change fast in varnish and the result will be cracking and crazing.

I am not working to nearly the same standards as your bows. I don't mind some finish flaws and am not looking for a rubbed out type look, just a thin varnish finish.

As far as the asphaltum/linseed being a paint/stain, I think you're right. It'll dry sooner or later, but it might sag and settle before it does. I wonder if the heat just speeds up oxidation? Who knows. If it dissolves in turpentine, I might thin some of my varnish with turps and put asphaltum in it and see if it partially cures in the sun in a day. My varnish gets hard, but not like lacquer - it might work well. It dries slow enough that it pretty much flows out level or smooth on any surface that it's on.