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Nitric acid and firescale


#1
i'm 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? 

I used to do this regularly and it worked beautifully. I’d
string a batch of rings together on a silver wire and dip them
for a short time, if I remember right, maybe 30 seconds or a
minute. The firescale would turn black. Whatever this black
compound was, it was soft and could be easily polished off
without obliterating all the detail.
I haven’t used this technique for a long time. Firescale
doesn’t seem to be much of a problem if one uses an alcohol and
boric acid dip before heating. And no one, of course, likes
nitric acid. Regardless of how carefully you seal up the
container, it seems to cause every metal article within about a
hundred feet to rust.
But as a firescale removal technique it certainly beats trying
to polish it off.

Neal Nye
@nnye