Many moons ago, I had a gallon of it (and may still, somewhere…). I
asked MaryAnn Scherr for a copy of the lab report she’d had done up
on it, to figure out what it was. As I recall, it was mainly sulfuric
acid, with a little thiourea. No HF at all.
This was important, as I was desperately trying to get AWAY from
using HF etches at the time. (This was in gradschool, roughly 1993 or
so.) I’m in the middle of moving, so most of my research notes from
back then are packed away, but I think I may even still have the lab
report in with my notes. If it becomes a big deal, I think (?hope?) I
know where all that stuff is.
I’d also heard that it was no longer available, as of a few years
ago. But with the advent of Bill’s Multi-Etch, I haven’t bothered
worrying about it. Multi-etch works much better than No-San did.