debkaplan3 on fri 23 feb 01
Hi all,
I've been experimenting with the combination of silver clay (aka PMC
Precious Metals Clay or Silver Art Clay) and white stoneware. Has anyone
else worked with this combination? I've seen the current article in Ceramics
Monthly but I'd love to know more. Some of the work,which I would love
comment on, is the following:
1. Adherence to glazed surfaces vs bisque surfaces - my experience is that
PMC works with both, if using silver slip need 3 heavy coats.....bond seems
stronger on bisqued surface. However, some current experiments attaching
silver (PMC) medallions to bisqued surfaces has resulted in:
a.some perfectly ok
b. some with curled up edges of the PMC!!! Does anybody know why?
2. Using glaze over silver clay; bisque, then fire on silver clay, polish,
apply glaze, fire cone 010 or less, looks great
3. pit firings: procedure: bisque, apply silver clay & fire, pit fire with
kosher salts, copper carbonate etc...; results
a. beautiful results, need to polish silver area
b. where heavy carbonization silver clay peeled ? Why??
c. 1 out of 5, temperature went too high, silver metal beaded up......I
can live with 4/5 good ones
Thanks
Debbie Kaplan
Snail Scott on fri 23 feb 01
At 07:58 AM 2/23/01 -0500, Debbie Kaplan wrote:
>silver (PMC) medallions to bisqued surfaces has resulted in:
> b. some with curled up edges of the PMC!!! Does anybody know why?
PMC has a very high shrinkage (50%) and must be
mechanically bonded to the surface underneath
(i.e. very rough, to restrain the shrinkage and
force it to shrink by thinning out, instead.)
Otherwise, it will try to shrink by pulling away
if it can.
>3. pit firings:
> b. where heavy carbonization silver clay peeled ? Why?
PMC has lots of organic material in it as a binder,
and to hold the water which acts as the vehicle.
If the pit firing didn't allow proper burnout of
the PMC organics, the resulting carbon might very
well inhibit adhesion of the PMC to the pot. If
your firing materials had poor enough combustion
to result in that much surrounding carbon, the PMC
in the same areas would also suffer inadequate
burnout.
-Snail
debkaplan3 on fri 23 feb 01
Dear Snail & all,
Shrinkage may be the key however, I use PMC+ which has a shrinkage rate of
10-12 %. I have already bisque & glaze fired the stoneware. Therefore the
shrinkage is complete for the stoneware & just begining for the PMC+. Will
try firing the PMC+ 1st then adhering it to the stoneware. I get very
strong attachment using PMC+ slip.
With regard to the pit firing, I bisque the stoneware, add PMC+, then fire
again to 1650 F, at which temp the binder in PMC+ burns out. Then I pit
fire. Can there be something about the make up of silver & carbon? If I
place my piece on a rock, raising above the level of the ash, I get little
carbonization & the PMC+ sticks well. But I like the silver on top of the
black.
You sound like you have worked with PMC. I'd be delighted to hear of your
experiences particularly as it relates to use with stoneware,
porcelain,.....
Debbie
At 07:58 AM 2/23/01 -0500, Debbie Kaplan wrote:
>silver (PMC) medallions to bisqued surfaces has resulted in:
> b. some with curled up edges of the PMC!!! Does anybody know why?
PMC has a very high shrinkage (50%)
>3. pit firings:
> b. where heavy carbonization silver clay peeled ? Why?
PMC has lots of organic material in it as a binder,
and to hold the water which acts as the vehicle.
If the pit firing didn't allow proper burnout of
the PMC organics, the resulting carbon might very
well inhibit adhesion of the PMC to the pot.
-Snail
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