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Silver metal clay turns brassy


#1

Silver metal clay turns brassy after immersion in jewelry cleaner?

I got a gift from my mother-in-law, a small round “basket” bead on a
silver chain. The set was tarnished so I dropped it in some
commercial cleaner (Hannoush Jewelry Cleaner, largely ammonia), left
it in 2 minutes per the instructions on the jar, and when I removed
the items, the chain was sparkling but the bead had taken on an ugly
brassy yellow color. Soaking it in hot citirc acid solution also
didn’t help.

I sent email to the gallery where it was purchased (in England),
explaining what had happened and asking what the bead was made of so
that I could clean it. I’m awaiting more from the person
who actually made the bead, but the gallery owners told me the bead
had been made from a silver metal clay. Which doesn’t help, since
cleaning isn’t different as far as I know. All I can wonder is
perhaps the clay was incompletely fired?

In my determination to clean the darn thing, I put some boraxo on a
toothbrush and scrubbed it, which took the brassy color off, but
also marred the shine on the surface. Oops. I think the only solution
to this now is to have it plated.

But I’m curious to hear opinions as to the reason for the brassy
color.

Thanks,
Christine in Littleton, Massachusetts


#2

Christine,

I work in Silver metal clay and although I can’t tell you why it
turned brassy, I can suggest a way to get the shine back. Why don’t
you try using a Dremel polishing wheel with red rouge to gently buff
it up? I use this on my pieces and it makes them look just brilliant,
with very shiny mirror finish.

If this doesn’t work, let me know. I have some other suggestions.
However, I would not use harsh chemicals on it, so let me know if
you need more suggestions. Remember it is pure silver (.999) and may
more easily combine chemically with other substances (like ammonia)
because of this.

Hope this helps!

Laura


#3

Christine, although I am just a beginner in art clay, I will mention
that when I dipped a ring quickly in hot very dilute sulfide
solution, it took on a nice golden (you could say brassy) color.
Leaving it in longer darkens it to more of a bronze, with colored
highlights.

For what it’s worth.
Margaret

p. s., – I forgot to mention that this effect can be removed by
heating with the torch.


#4

This is a bit of a mystery to me as well. If it’s made of metal
clay, then jewelry cleaner should definitely have done the job.
Actually, when you first described the incident, I had thought that
the bead had actually been plated first and that the ammonia had
destroyed the outer layer.

But if it’s truly metal clay (and that has yet to be confirmed)
simple jewelry polish (not cleaner, but polish) should restore the
shine. The important thing, now is to find out what it’s really made
of.

Jackie Truty
Art Clay World, USA, Inc.


#5

Here is a post from Metal Clay Gallery yahoo list that may shed some
light on the recent question about the metal clay turning brassy.

Elaine

  I have been using dry casting investment (powder) as a support
  for odd shaped/hollow objects, I use a dust mask. It works
  great but I have noticed that the items develop a golden/brassy
  tarnish, at the contact points with investment, within 10
  minutes in my tumbler. Scrubbing with a wire brush doesn't
  remove it. This tarnish only comes off with (yikes)Tarnex! I've
  tried a good long soak in strong hot pickle and it just doesn't
  work as well. After the 2 minute Tarnex dip I rinse it in water
  then neutralize it in hot baking soda and water. The pieces
  tumble up beautifully after the dip. I <snip> Vicki 

Elaine Luther
Metalsmith, Certified PMC Instructor
http://www.CreativeTextureTools.com
Hard to Find Tools for Metal Clay