PMC Sterling Rings

Pictured here are a group of rings I'm working on for my upcoming CraftCast webinar on April 4th and for my pre-PMC Conference class. Mostly I'm enjoying the process of learning about another new material, its pros and cons, and how to best integrate it into my studio.

About the rings: They are all about the same size as this makes it easier for me to keep track of the shrinkage and determine if it's regular.

They are all 'open' because I haven't wanted to do this in fine silver clay and PMC Sterling seems a perfect opportunity. They are all carved because it's simply one of my favorite activities and PMC Sterling does it so well. I have discovered something: The drier the clay, the more it's likely to chip when carved. If you're carving PMC Sterling and it chips try giving it a "steam bath". By this I mean, put it in a hydrating environment briefly then carve. This might be 10 minutes but it depends on where you live, the thickness of the piece, etc. Don't overdo the hydration or it will get floppy and while this is good if you want to re-form the piece, it may make it too fragile to carve.

Once I form, refine and carve the rings I begin trying different solutions. I have a lifetime of pebbles and pieces, not to mention those I make, to house on the rivet wire that joins the two sides of the ring band.

I love working this way: On one side of my desk I have a pile of treasures I've collected or made over the years: rocks, beads, baubles and bits. On the other side I am making and carving ring shanks, the solutions for the orphans in the other pile, the 'bits' pile. The fun is in mixing and matching them up then sorting out the inevitable problems that occur when joining disparite materials.

This hollow form "flip ring" looks straightforward but actually depends on a tube inside the hollow form through which the rivet wire will go. Without the tube, the rivet wire would simply bend inside the hollow form. Fortunately the PMC Sterling's longer open working time serves it well for use with the extruder and the tube was easy to make.

Later this month I'll be posting examples of other rings that will be featured on the Craftcast webinar.

Testing the new PMC Sterling

I am captivated by the new Sterling PMC; having worked with it since the spring, I want to write a little bit about my experience.

I’m thrilled to be able to say it’s very strong when fired and lovely to work with when fresh. Like PMC Pro, it has a longer open working time than other versions of PMC. When dry, it’s generally similar to dry PMC3 or Plus except it's much easier to carve with gouges. It carves smoothly without chipping, like PMC Pro and like BronzClay.

Sterling PMC needs to be fired in 2 stages, a brief air fire and then a carbon firing. This is more complicated than the needs of fine silver PMC and at first it loomed large as a drawback for me. As I began to appreciate its strong points, however, the double firing became a lot more tolerable.

What follows is a brief story of my experience with the material to date. My plan for the winter is to explore more open work, more ring designs, hollow forms, and larger kiln loads. To be able to rely on metal clay for the kind of strength required by this type of work is thrilling to me. I look forward to developing ideas that I have been reluctant to do in PMC and also reluctant to fabricate in sterling metal.

Five Rings in Sterling PMC:

Please note: The times and temperatures I used in the firings described here were part of my testing process. The times and temperatures described in the PMC Sterling insert are our up-to-date recommendations for firing.

All of these pieces were fired at 1000F for 30 minutes then 1510F for 45 minutes, in well used coal carbon. All were fired with approx. 10mm of carbon on all sides (ie not much carbon).

The first (corset ring, 4 cards thick) was fired flat as a strip then keum-boo-ed on the inside surface with two layers of 24k foil (the gold adhered nicely, although a few tiny spots resisted the bonding). Then the strip was formed into a ring around a mandrel, laced with wire, patinated and polished.

This bee ring was fired face down and in spite of the band being thin, it did not warp or slump. The bee is quite thin, but strong and unmovable with my fingers.

The bee was more challenging to keum-boo than the corset ring, I think because the corset has no texture on the inside.

There was some staining on the surface of the bee that seemed to repel the gold. I tried cleaning it off but I couldn’t get the gold to adhere to some spots. This type of staining, after the carbon firing, has not happened again. The fact that the gold adheres as well as it does to the sterling without depletion gilding or any other preparation is still a mystery.

I made the snake to test a thick piece and to try carving the sterling clay. It is superb to carve.

I made this ring to test strength in open work pieces and also attachments like the little balls, which I attached with slip. It did well on both counts. The ring is thin but strong and the balls are not coming off.

I fired this ring face down in the carbon with a piece of kiln paper under the cutouts and on top of the cutouts so the carbon granules would not jam into the cut out areas. This worked perfectly well although the ring itself is too thin to be practical. In spite of it being thin, it did not slump. I fired this ring with 4 other pieces; two hollow tubes and two flat pieces. All fired to strong metal.

(dry ring)

(ready for firing)

This cylinder is the first hollow form I’ve made in sterling PMC. The caps on the top and bottom are donuts (rather than solid clay). I did this to conserve material. The cylinder did not distort in the firing; next time I will make it thinner walled and lighter weight.

I’m experimenting with firing more pieces in the carbon. The cylinder was fired with 4 other small pieces: 1000F in air for 30 minutes then 1510F in coal carbon for 45 minutes. All pieces are strong and well sintered.

I'll write more as I experiment more and experiment I will. As with the BronzClay, and then the PRO, I look forward to discoveries I'll make bumping along in territory that is not entirely known. As with everything to do with metal clay the pleasure is in the pioneering (well, at least most of the time).

I look forward to hearing about your discoveries, as well!

I'm teaching a PMC Sterling ring class before the PMC Conference this summer. The class is full but please let me know if you'd like to be on my mailing list for upcoming PMC Sterling classes.