Peroxide & Vinegar

Jewelry Discussion
21

Judy Bjorkman,

As far as I could tell from Amy’s post her student’s copper plating
was the result of pickling the brass and not heating the brass.

A cuprous oxide or a red heat patina that can be achieve on copper is
more difficult to achieve on brass. The color of the copper left by a
zinc depletion plating is a dull soft copper and not as intense as
the red heat patina of cuprous oxide.

Since we can not see the metal we are discussing, I based my
assessment on the years of similar experiences I had while teaching
metalsmithing at the college level. I also experienced the zinc
depletion plating of brass as journeyman goldsmith while finishing a
brass sample line.

Back in the late 1970s road reps would carry small independent
jewelry maker’s lines around the country taking orders. Often the
jewelry makers could not afford to send out “live” goods (real gold &
diamonds) lest they be stolen.

So brass samples with cz’s where made and gold plated. Often the
brass samples did not cast as well as would be hoped for and repair
work would need to be done, thus the soldering, the pickling, the
zinc depletion and copper plating.

If you find this difficult to believe, test it for yourself. place a
piece of cold brass in cold pickle and within an hour you will begin
to see a dull copper (zinc depletion) plating occur on the brass. Of
course heat speeds this process. And while some zinc may oxidize
during soldering procedures, even without any heat, pickle will
dissolve zinc from the surface of brass.

Nanz Aalund
Associate Editor / Art Jewelry magazine
21027 Crossroads Circle / Waukesha WI 53187-1612
262.796.8776 ext.228

22

I too sometimes get a pink copper coat on some of the brass and
silver I pickle. After reading Bill Seeley’s short article on
Hydrogen Peroxide Pickle several years ago, I began to keep a bottle
of drug store peroxide (3% H2O2) near my bench. If I have a copper
flash I need to pickle off, I just dump some peroxide into the
pickle pot with the existing Sodium BiSulfate (NaHSO4, Sparex #2 tm
type acid). It works like a charm and also replenishes the lost
(evaporated) water. While I have other acids available, I rarely use
them. Many are volatile like HCl (Hydrochloric or muriatic acid),
HNO3 (Nitric acid), or Acetic acid (vinegar is around 5%). The
resulting fumes, especially when heated, can be hazardous both to
your health and to your tools, causing a lot of rust. Some safer
acids like citric acid seem too weak. Others are just too hazardous
like concentrated H2SO4 (Sulfuric acid) or volatile, hazardous and
hugely dangerous like HF (Hydrofluoric Acid) and NaCN (Cyanide).
Like I said I have these other acids and will occasionally use them,
but only for a special case and with great care. I am very intrigued
by the Reactive Metals Studio Multi-Etch product. Not only do they
say it works on Titanium, but “It etches copper, brass, pewter, steel
and will clean light fire scale from sterling.” Like everything
Reactive sells, I assume this has to be ‘best in class’ and work well
or they would not sell it. It is however dangerous, if not especially
hazardous. It contains NaF (Sodium Fluoride) and perhaps acid
sulfate and nitrate salts. It has a very long shelf life when dry,
but decomposes once mixed (at least 6 months life) and is available
in minimum one gallon size, which must be mixed all at once. I sure
wish it was available in in smaller units, like an 8 pack of 16oz
packets so I would have less to store once mixed and less to dispose
of. Do any of you have any experience using MultiEtch?

Marlin in Denver on a great Autumn day.

23

I recently had some rings cast in bronze. They came out red on the
outside and black on the inside. I asked the castor how they treated
and polished their pieces and he said they put them in muriatic acid
and then tumbled them with steel shot and he showed me a finished
piece that had a good polish and was very gold in color.

But, and here is where my troubles start, having followed the
peroxide and vinegar thread I put them in this solution (heated) and
the red disappeared. The black remained so I put them in muriatic
acid (heated) and the black disappeared but some red came back.

During these procedures I see a very nice crystaline surface appear
and I think serendipity - If I could just keep the crystal effect AND
get a good gold color.

I have tried Sparex plus peroxide, Sparex plus peroxide and vinegar,
ditto for muriatic acid, first Sparex than peroxide and vinegar and
many variations but the pieces come out either too gray or too red.
Is
there a formula or is it just dump something into the solution until
you get the right result?

By the way, the crystal effect is not just superficial. I can file
and sand the areas that I want to be smooth and just by placing the
piece in a heated solution the crystal effect will reappear.

Lois

24

I would suggest you look under “metallurgical etches”

see to start:

I have a couple reference books – you might find some in an
engineering school library. What alloy is the “bronze” supposed to
be.

jesse

25

Hi–I am a new member replying to Marlin’s question (under peroxide
& vinegar):

Do any of you have any experience using MultiEtch?

I’ve been working with titanium since 1979 dba Exotica Jewelry.
After ten years of using hydrofluoric and nitric acids, while using
all the necessary but burdensome safety devices, I no longer wanted
to engage in such critical risk management… So I worked on
developing a safer alternative which I market as Multi-Etch–it has a
ph of 6.60–almost neutral.

I had the product tested by an industrial hygiene firm and the
following are a few quotes from their report.

“The mixture, if handled properly, is not a highly dangerous
solution.”

“Working with the materials inside a local exhaust ventilation hood
is recommended.”

“It appears from the current literature that flushing the spent
solution down the drain using copious amounts of water as a method
of disposal is adequate in regards to the percentage of hazardous
ingredients in the spent solution.”

I performed air sampling with Draeger tubes while etching titanium
and consistently got zero readings for fluoride/fluorine gas. In
other words, Multi-Etch is not as safe as water but with care, can be
used without fear.

What it will do:

– Prepares titanium for anodizing brilliant colors, i.e., voltages
over 50. Removes anodizing mistakes on both titanium and niobium.

– Can be used with other metals too. It will not remove silver or
gold ions but zaps away copper flash/light fire scale.

– Great on mokume for producing dimensional etches.

– Works great on copper and brass.

– For platinum it’s the only thing I’ve ever used for the final
cleaning prior to welding/soldering.

– Removes broken drills/taps from titanium, niobium, silver, gold,
or platinum.

– And yes, I’ve even used it to get rust stains out of my
daughter’s clothes! But note, rinse real well or it will put holes in
the clothes.

Hope the above is helpful.

Chris Boothe
(800) 297-6707

26 
I'd be interested (I'm sure all of us will be) in the results of
the etching on platinum, and if so, would that include rhodium? I
take many painful tech calls requesting a way to remove rhodium
plating.

I originally perfected Multi-Etch for titanium production. It’s a
nonacid alternative to hydrofluoric acid. I’ve also tested it on
other metals with great results. I manufacture a line of titanium
wedding rings with platinum inlays. As all platinum fabricators are
aware, the accepted method to remove cross-contamination prior to
welding or soldering is a 15 minute soak in nitric acid or bisodium
sulfate. With Multi-Etch, a 15 second dip is sufficient to eliminate
all impurities that could interfere with a perfect weld or solder
joint.

The equipment I use is available everywheRe: the standard off the
shelf pyrex measuring cup and single coil hot plate with a heat
diffuser (don’t place the cup directly on the hot plate.) Do this
under a fume hood or outside. For one ring I use 1/8th cup of
Multi-Etch, heated to about 150 degrees F. You can use a thermometer
or look for the built in Multi-Etch bubbles which tell you when it’s
ready to use (visual check.) These tiny bubbles appear when the
Multi-Etch is brought up to the correct temperature. I dangle the
platinum from a niobium wire into the Multi-Etch for 15 seconds and
then rinse in distilled water. It’s now ready for a perfect weld.

By the way, Multi-Etch will etch glass so as a rule I replace the cup
every 3 months–it can shatter and make a mess. If you’re
high-production, then replace the cup more often.

I’ve done limited testing with Multi-Etch on platinum for etch
effects, that is, removal of platinum ions, and there doesn’t seem to
be any effect. I have not tested it with rhodium plating but I assume
there would be no effect on that either. I’d be interested in
hearing from other platinum workers how they would compare Multi-Etch
to the standard protocols of platinum cleaning. Multi-Etch is
available
through Reactive Metals Studio, reactivemetals.com.

Thanks all you fellow metalheads!

Chris (Electro-geezer)
Exotica Jewelry
(800) 297-6707