G’day; my suggestion (for what it’s worth because I’ve never had
to do it) is to put the work into a approx. 50% slightly warmed
solution of nitric acid: sterling and fine silver dissolve easily
and rapidly but gold doesn’t;
Hi John,
I guess (!) that the copper will also be dissolved, leaving a
fine gold surface layer. And: provide ventilation, it will eat
holes into your lungs!
regards, Markus
Wouldn’t dipping silver into Nitric acid strip the silver away
as well as the frestain? Wouldn’t electrostripping be better to
remove firestain? Richard W UK
Hi, Ive just moved out to the west coast and am looking for a
sourse for Nitric acid. Back in the midwest I used to refine
(Chemical seperation) with a chemical grade(40 % ?) Nitric which
I purchased thru a friend in Indiana. It was cheap then.Does
anyone know where to get in touch with a supplier in California,
or prehaps out west somewhere?
Hi, I’ve had the same problem in Oregon, have to sign your life
away to buy anything like nitric acid. Nevada does not have such
restrictions so I buy it at a chemical supply place in Reno. Check
the chemical supply places where you live to find out Cal.
restrictions and if all else fails take a trip to Reno or Vegas. Jan
McClellan http://www.designjewel.com
Have you checked with the chemestry departments of your local
schools (colleges or universities?) Sometimes they can supply you
with what you require.
Try Bryant Labs,
1101 5th
Berkeley, CA 94710
510-526-3141
or
Chemicals for Research and Industry
2928 Poplar
Oakland, CA ???
510-893-8257
They both carry nitric acid. I do ot know if it can be shipped but they
will let you know what is possible.
John
John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc.
PO Bx 44, Philo
CA 95466
Ph 707-895-2635 FAX 707-895-9332
The playfulness of the Universe
is reflected in the dance of the stars!
Not to quibble Al (but quibble I must). Nitric does gradually
turn blue as it etches sterling silver. It also is etching the
copper in the sterling, forming copper nitrate. It’s still got a
lot of punch, however, even when blue. It will turn pretty deep
before it isn’t any good anymore.
Now for another “nitric question”; I know there’s an easy answer
(but I can’t seem to figure it out):
This weekend I tried ferric nitrate for the first time, in an
effort to find a less noxious way to etch silver than using
nitric. This was at the suggestion of another Orchidian, who
electroetches with it. I didn’t have a gram scale available, so
my measurements were approximate. I added about 100 grams of
ferric nitrate to 250 ml water. The color of the solution was a
medium amber. There was no heat generated at all when I added the
crystals to the water (I was a little surprised at this), nor
were there any fumes whatsoever (and I have a very sensitive
sniffer for this stuff). After 3 hours in the bath, the silver
was slightly etched, but with very little depth. Still no fumes.
(I was using a covered container.) At this point I warmed the
solution slightly by placing it in a sunny location. This on the
cool Mendocino coast with the white caps whipping it up would
have brought the temp up to about 75 or 80 degrees max, just
tepid. After another hour or so I checked the bath. When I
removed the lid, I noticed the strong odor of nitric acid right
away. The silver was significatly etched. After I transferred
the solution to a bottle I neutralized the remaining few drops of
ferric in the tray with baking soda, to much fizzing.
Question: Obviously this process formed nitric acid. But why
wasn’t it formed when I originally added the crystals to the
water? (no heat or odor whatsoever) The only thing I can think of
is that the chemical reaction began with the slight increase in
heat (and it was very slight). Would any of you be able to fill
me in on the precise chemistry? Also, what would be the strength
of the nitric in my solution, given my proportions? (“Qual” I was
OK at, but I almost flunked “quant”.)
Thanks for flexing those brain cells!
Rene Roberts