Hey Don,


Yeah, I worded that poorly. What I meant was that Nitric works faster
for any given temperature.


That may very well be true, however the immersion times with the citric
acid are not excessive. They recommend 2-5 minutes at 120F-160F, and
that seems to be giving me good results. Ask me in another two years ;-)

That should be fine. Most folks don't have temp baths to work with, so
I assumed you would be working at lower temps. There are also
off-the-shelf ferroxyl test kits available for testing the surface
passivity if you want.


Yes. I always try to dip my parts in a temp controlled bath with some
sort of agitation. Sometimes this cannot be done because the part is too
large for my available containers.

A buddy of mine has a business specializing in sanitary piping and
equipment, custom s/s fab work, and mechanical / electropolishing /
passivation. I can hook you up with him if you ever need a larger piece
polished and passivated. He's in Tempe AZ (a suburb of Phoenix - but
don't tell them that).

Keith