I made a very detailed piece and in polishing discovered the
cursed firescale. Using zam as usual will obliterate the
engraved details, so am considering the use of a 50% nitric acid
dip. Aside from the cautions required in the handling of a
powerful reagent, does anyone have experience with this? The piece
was pre polished with zam and rouge before the detailing and
final soldering so that cleanup would be minimal.
Bill: Any time that I got firescale on a delicate piece( if it
wasn’t delicate I would just sand and repolish), was to use
concentrated nitric acid. I would take an eye dropper made of
glass, and wearing gloves, preferably under a fume hood, drip
the nitric acid onto the spots that had the firescale. By the
way this was done after the final rouge polishing. As soon as I
dropped the acid onto the piece I would drop it into a cup with
baking soda and water. This neutralizes the acid and you are
done.
Hope that helps,
Cary James