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silver contamination on mold

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SGS
Posts: 9
Joined: Tue Apr 17, 2007 1:28 pm

silver contamination on mold

Postby SGS » Mon Feb 16, 2015 6:45 pm

I'm trying to figure out a solution for a mold that got contaminated with silver . . . I know the key is prevention (!), but it has already happened, and I'm trying to fix it.

After finding out about it, I did the following: Cleaned off all the kiln wash, put on a fresh coat, and tested with french vanilla . . . yep, contaminated.

I've cleaned it again, and have thought about taking the mold up to (say?) 1500 degrees, and hold for a while (1 hour?) and see if it will fume totally off, then do another test.

Does anyone have any experience with this?

Thanks.

SGS
Posts: 9
Joined: Tue Apr 17, 2007 1:28 pm

Re: silver contamination on mold

Postby SGS » Thu Feb 19, 2015 1:45 pm

Does anyone have any experience/suggestions? Thanks. :-k

Valerie Adams
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Location: Santa Rosa, California
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Re: silver contamination on mold

Postby Valerie Adams » Thu Feb 19, 2015 2:01 pm

I only have very limited experience with fine silver encased between two sheets of glass. Even though the silver wasn't touching my shelf and had what I thought was plenty of glass surrounding it (therefore no fumes leaking out the edges), I still had heart shaped stains on my shelf. The silver was heart-shaped wire.

I discovered the staining on the next piece, which was spring green opal. Figuring it would be gone by then, I discovered stains on a French vanilla piece. Both of these pieces had perfectly formed hearts stained on the backs!

After that, I fired the shelf to 1500° two or three times by itself. Haven't had a problem since.

SGS
Posts: 9
Joined: Tue Apr 17, 2007 1:28 pm

Re: silver contamination on mold

Postby SGS » Thu Feb 19, 2015 3:05 pm

Thanks, Valerie,

I fired to 1500 once, tested, still some marks (very discouraging).

So I cleaned them again (don't know whether that helps or not) and they're in the kiln now with a nice long hold at 1500 -- hopefully that will do it.

Thanks, again.

rosanna gusler
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Re: silver contamination on mold

Postby rosanna gusler » Thu Feb 19, 2015 3:25 pm

you can also try firing with a heap of bentonite clay on the stain as hot as your jiln will allow.
artist, owner of wanchese art studio, marine finisher

SGS
Posts: 9
Joined: Tue Apr 17, 2007 1:28 pm

Re: silver contamination on mold

Postby SGS » Thu Feb 19, 2015 6:03 pm

Thanks, Rosanna,

Just ordered some . . . about the "as high as the kiln will go," do I need to worry about that affecting the molds? (I can go to 1700.)

I'll be testing again, and if the firing I've done doesn't work, I try the bentonite.

Thanks,

Sherry

rosanna gusler
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Re: silver contamination on mold

Postby rosanna gusler » Fri Feb 20, 2015 7:38 am

Ceramic molds will be fine to 1700f. R.
artist, owner of wanchese art studio, marine finisher

SGS
Posts: 9
Joined: Tue Apr 17, 2007 1:28 pm

Re: silver contamination on mold

Postby SGS » Fri Feb 20, 2015 11:06 pm

Thanks, Rosana,

The bentonite came in the mail today . . . but I checked my 2nd test run today, taking the molds to 1500 with an extended hold (I did it twice, plus cleaning off the kiln wash both times), did the trick! French vanilla came out beautifully with no marks.

I have the bentonite stashed away so if this ever happens again (and I'm hoping not!), I'll try to do one firing with bentonite up to 1700.

A positive learning experience!

Sherry


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