I got a little bit of 70% nitric acid, potent stuff. I cut the end off a screw
of the same exact type as I previously dissolved in alum, put it in the bottom
of a small glass, and added about 10 drops of nitric acid. Naturally, I wore
face shield and gloves, and used an exhaust fan. Nitric is pretty nasty. Anyway,
it was cooking along nicely for a few minutes but then it seems to have slowed
down quite a bit. It's been going about 8 hours now, and I'm wondering if there
is enough oomph in the little bit of acid I put on it, barely enough to cover
the bottom of a small water glass.

Thing is, my actual screw, which is in an aluminum casting, won't have much acid
around it either.

I suppose I could try drawing the liquor out carefully after it slows, and
adding a few more drops.

Anyway, tomorrow I'll take the piece out and weigh it and I'll get a rate of
dissolution and then I'll compare it to how the alum did.

GWE