Firing PMC with garnet beads?

Jewelry Discussion
1

All,

I’ve already told Ed, one of the managers of Indian Jewellery Supply
in Gallup, about this group. You have been so very helpful with your
advice in helping this unemployable software and electrical engineer
begin the process of reskilling into a precious materials machinist
(I wouldn’t dare call myself a jeweler! What else could I call
myself?).

I’m afraid I can only reward you with more questions as I go, as my
imagination branches out and blossoms as I explore further.

Here goes:

I intend to use PMC in place of bezels for setting gems of my choice
into my casted or milled fine silver designs, seeing as how I will
have yet to master bezels for a very long while.

(I know the masters here would seriously frown on using PMC as a
setting technique. But if they were musicians they would be playing
to the elite audience, and I would be a klezmer playing at proms and
bar-mitzvahs, so I want to design the best roadside jewelry I’m
capable of as I continue to pay my dues for this new trade.)

Of course, that limits my choice of gems. But garnets are listed in
PMC groups and websites as being entirely suitable for exposure to
molten silver. They

come in a variety of colors, they are very difficult to treat or
fake (I’ ll know it’s fake if it melts or burns!), and the price
range
at the low end is quite affordable. So garnets would be a really good
entry level choice.

Of course, garnets are only available in bulk as beads, or as pebble
rough too small for faceting (as at facetroughgemstones.com).

Focusing on the garnet beads for now, I notice that the faceted
stones on some strands are even quite pretty were it not for the
holes.

But I wonder: if I take a stone off the strand, thread it with fine
silver wire, anchor the wire into the work, and then fill the gaps
between the work and the stone with pmc, will the silver wire still
be noticeable through the gem?

Also, I had thought that a pebble rough garnet could look nice if
set under the right circumstances, but I wasn’t sure what a master
would think if I did that?

I know I’m exaggerating, but basically I’m asking the masters and
other experienced among you this question:

I start with cruddy materials like faceted beads and pebble rough
will they still look like crud no matter how much care I take to make
it look otherwise?

Or is part of the job of a capable crafter to use as much care as is
needed to start with crud as raw materials and make the finished
result worth a second look?

It’s a fundamental question, but I think it’s worth asking.

Thanks,
Andrew Jonathan Fine

2

Hi Andrew

Early on, when PMC first came out, I was using the Standard and put
Garnets in the casting. It was then only 1650 degrees for 2 hours,
and the garnets came out black. I have never tried it again.

With the new less heat and shorter firing time - with PMC+ and PMC3,
you might be able to get this to work…I wouldn’t try expensive
ones!

Good luck,
Rose Marie Christison

3

When heating garnets with silver clay, you should use one of the low
fire clays (PMC3 or ACS650) and fire at the lower temperatures.
Hotter and longer firing schedules sometimes causes a hematite-like
sheen on the surface of the Rhodolite due, I think, to the chemical
composition of the stone. If you have a batch of stones from the same
source, testing one may give you an idea of what will happen, but
there are no guarantees. Tsavorite seems to be more stable. Hessonite
falls somewhere in between.

For more on this, check out an article I wrote on the subject at:
http://tinyurl.com/dagostino-garnets

In addition to the book already mentioned, two other sources for
setting stones in metal clay are:

L J Davis Setting, Gemstones in Metal Clay:

http://tinyurl.com/Davis-gemsetting

and M E D’Agostino, Using Investment Models to Set Stones in Silver
Clay:

http://tinyurl.com/dagostino-setting

Mary Ellin D’Agostino, PhD
www.medacreations.com

4

Andrew,

Of course, that limits my choice of gems. But garnets are listed
in PMC groups and websites as being entirely suitable for exposure
to molten silver.

As you’ve expressed concern about the aesthetics of setting garnet
beads, why not try the first few times using cubic zirconia They’re
safe to fire, and if the outcome is less than you’d hoped for, your
heart and your pocketbook won’t be broken.

Lorraine

5 
Focusing on the garnet beads for now, I notice that the faceted
stones on some strands are even quite pretty were it not for the
holes.

As you say, garnets are affordable at the lower end. Why not find a
reliable supplier of faceted garnet stones - then you wouldn’t have
the problem of the bead holes? I buy decent garnets in calibrated
round and oval sizes from a UK seller. I’m sure you could find a
decent supplier where you are.

Helen
UK