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Etching gold in sterling bimetal


#1

Hello,

I’ve been having all sorts of fun etching patterns into Reactive
Metal Studios’ copper/silver bimetal (I’ve only had luck etching away
the much thinner copper layer with ferric chloride, no luck etching
away the thicker silver with ferric nitrate – the piece starts to
deteriorate before you get through the silver). Now I’m dying to try
a project with their 22K gold/sterling bimetal (want to etch away the
silver, leaving a silver pattern on gold). The stuff is pricey or
otherwise I’d just experiment. I’ve been looking through the Orchid
archives and my books but I can’t find anything that says for sure
that ferric nitrate won’t etch the gold too.

To make it even more complicated, I’m guess the the gold layer in
the bimetal is thinner than the silver or else it would be even more
pricey. If so I’d run into the same problem as I did with the
copper/silver bimetal, when trying to etch away the thicker layer.
(I could try shellacking the *$#%^ out of the gold and the sides of
the piece, so the ferric nitrate doesn’t get a chance to undercut).

So…is there any chemical that will etch away the gold and not the
silver?

Help! This is not a time I want to create one of my signature
of-course-it’s-art-I-MEANT-to-do-that (aka “ooops”) pieces of
jewelry.

Mona


#2
Now I'm dying to try a project with their 22K gold/sterling
bimetal (want to etch away the silver, leaving a silver pattern on
gold).  The stuff is pricey or otherwise I'd just experiment. I've
been looking through the Orchid archives and my books but I can't
find anything that says for sure that ferric nitrate won't etch the
gold too.

Mona,

Gold is very resistant to chemical attack which makes it a popular
masking layer in my work. It is very likely that ferric nitrate will
not etch gold. One gold etchant is potassium iodide and iodine
(KI/I2/H2O in 4:1:40 ratio by volume) and the other is aqua regia
(HCL/HNO3/H2O in 4:4:9 ratio by volume). Cyantek AU-5 is one example
of a commercially available gold etchant.

To make it even more complicated, I'm guess the the gold layer in
the bimetal is thinner than the silver or else it would be even
more pricey.

Thea Izzi told me that 10% of 24 gage bimetal is 22K gold.

If so I'd run into the same problem as I did with the
copper/silver bimetal, when trying to etch away the thicker layer.
(I could try shellacking the *$#%^ out of the gold and the sides of
the piece, so the ferric nitrate doesn't get a chance to undercut).
So...is there any chemical that will etch away the gold and not the
silver?

Sorry, I don’t know of an etchant that will etch gold and leave the
silver.

Jeff Simkins
@Jeff_Simkins


#3
Well, if you are talking about Shining Wave 22K Bi Metal here is
what you g= et- 

Composition: 8.3% 22K gold, 91.7% Sterling silver
Weight: 12.5% 22K gold, 87.5% Sterling silver The 22K layer is 1/8th
the volume, 1/12th of the thickness.

If you etch away much of the silver the metal will become very week.
The silver provides a strong backing so the object will hold its
shape.

From a design point of view I have always thought that the concept
of carving/engraving through the 22K to reveal the sterling was the
most interesting. The sterling would patina to black. The patina
would age and wear well becuse it would be protected by the
surrounding gold. Black and gold=8A not a bad look. Bill

Reactive Metals Studio, Inc.
PO Box 890 * 600 First North St. * Clarkdale, AZ 86324
Ph-928/634-3434 * Ph-800/876-3434 * Fax-928/634-6734
@Michele_Deborah_Bill


#4

Thanks, Jeff! Reactive Metal Studios confirmed that the gold layer
in their gold & sterling bimetal is much thinner and recommended
etching with aqua regia (apparently it will not etch the silver). Is
anyone aware of guidelines for etching gold with aqua regia (where to
buy it, does the solution need to be agitated as when etching with
ferric nitrate, toxicity, etc.?)

Mona