Firing sterling with PMC

[Pat_Waddington]

What is the best way to protect sterling silver from
discolouring/firescale when firing it with PMC? I exclusively use Art Clay 650 or PMC3 so that I can fire it with a butane torch, but have been reluctant to mix sterling and PMC because I am worried about ruining a piece if I damage the sterling. I have read all the info I can find about anti-firescale, but this forum provides so much that I am thoroughly confused! I need a simple,

inexpensive solution to the problem as I do not have a need for large quantities. Would painting the sterling with a mixture of borax(?) and denatured alcohol suffice?

Christmas is coming and I expect there will be no Orchid for a few days over the holiday - I will miss my daily fix!



Orchid is not resting this year :-)



Best to all
Pat

[E_Luther]

Best not to embed sterling wire in PMC. The extended firing time
makes something in the alloy do something weird, to speak
scientifically, and the sterling -- say it's wire that extends
beyond the PMC piece -- will become brittle and break off.

Then if you look in the center of the wire, it looks seriously
changed and different. It's not the silver that does this, it's
something in the other 75 parts/1000.

Use fine silver, or solder on the sterling later.

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

[judymw]

Hello Pat,

First, have you checked the PMClay website? You can ask technical
questions and get an email response. This sounds like a Tim
McCreight question.

The Japanese invented PMC and have published some fascinating books
illustrating various techniques. I can't read Japanese but looked at
the photos, which showed sterling used as a base and completely
coated with PMC. When I need a bail or other finding fired into a PMC
piece, I use heavy fine silver. Has worked just fine.

Judy in Kansas

[bericho1]

Well, I've not worked with PMC3 that much, but I understand that one
of the pluses of PMC3 is that you can use sterling findings with it..
PMC3 fires quicker at a lower temp and shrinks less which I think is
one of its advantages that allows the use of sterling findings.

Kay

[Pat_Waddington]

Hi Elaine,

I always use fine silver wire with PMC, fine silver bezel strip and
fine silver sheet where appropriate. In this case I was looking to
attach cufflink findings. Guess I'll just have to learn to solder.

Thanks
Pat

[E_Luther]

I don't like to fire PMC3 (which, actually, I don't use) at the
lowest possible temperature because it's not as strong. Firing PMC+
and PMC3 at the schedule for PMC Standard (1650, 2 hours) gives you a
5% increase in density and makes the item as dense as cast fine
silver.

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

[Pat_Waddington]

    I don't like to fire PMC3 (which, actually, I don't use) at
the lowest possible temperature because it's not as strong.  Firing
PMC+ and PMC3 at the schedule for PMC Standard (1650, 2 hours)
gives you a 5% increase in density and makes the item as dense as
cast fine silver.

With the best will in the world, I can't hold a torch for two hours
But getting my kiln next week.

Pat