Friday, November 26, 2010

Playing with PMC Pro...

Well, I think I'm hooked... I actually didn't want PMC Pro to work so well because I've never been a fan of the whole carbon business... but it does. This stuff is soooo tough! This ring has a band as thick as a nickel and it won't bend - I tried to twist it and it didn't budge.

Not that I think Pro will replace my other silver clays, but for some applications it's going to be great. Again, not a fan of the carbon, but for making tough rings or delicate parts, I can get around that...

This ring is only 3 cards thick - and with the shrinkage rate being greater than PMC3, the resulting ring is even thinner than you'd expect. C'mon, who would make a PMC ring only 3 cards thick? Not me - till now. I tried to squeeze and crush it and... nothing.

Since that went so well, I made another one like it with some really skinny snakes around the edges (they worked beautifully) - also 3 cards thick and it won't crush either. I've asked students to try to squeeze the rings and they were impressed with the strength too. All the rings were fired in carbon for 1 hour. They were constucted @ 3.5-4 sizes larger. I didn't put any ring plugs in them. I figured if they got too small I'd just stretch them. I did end up stretching the wider band, but that worked just fine. 

And I wondered about making hollow forms - how small and thin could I make them? These tiny lentils (yep, that's a dime) are for earrings. They are only 2 cards thick. They could have been domed more, but I got caught up in the excitement of making them and didn't look for a better dome... 

And now the question you've been waiting for (OK, I was), how well does it WATER ETCH? 

The answer is (after a couple of tries) great! The best result so far is with my favorite wax (Mayco wax resist - on the heart shown here).

I did try my new kistka on this clay because it has worked well on PMC+, but with Pro I had some blistering issues. I shelf fired the all the water etched pieces prior to carbon firing to burn off the wax. 

after carbon firing
after shelf firing
In firing the first piece done with the kistka, I got distracted when I programmed the kiln for the shelf firing and accidently set it for 1400F (firing temp) instead of the recommended shelf firing temp of 1000F (not shown here). I thought the resulting blistering was from shelf firing too hot. So I tried it again with another piece (above right), this time at 1000F - but still got the blistering. Then I decided to try the Mayco wax. This time, after the shelf firing there was no blistering. It did shelf fire for an hour - I intended to stop the kiln after 30 mins but got busy and it ran the whole hour. But I don't think that was the difference. Just to be sure, I'm going to do another piece with the the Mayco wax shelf fired for 30 mins, and one with the kistka wax shelf fired for 1 hour to see if that affects the blistering. All the water etched pieces were then carbon fired (after shelf firing) for an hour. I just wanted to be sure they were fully sintered.

My tests were mostly designed for learning about the strength of this new version of PMC. The shrinkage rate is shown at left with the fired piece and the cutter used to make it. The clay is good and sticky with long working time, though snakes were still subject to cracking if you weren't careful. It made the smoothest slip - letting it rest after mixing is important.

The bails on the water etched pendants are only 2 cards thick and very strong! This two-card bail can't be crushed (with my hands), nor did it snap when I put some pressure on the joint - which was not reinforced from the back.

So I'm impressed. I can see using it for ring bands and more delicate bails and findings. I have many more tests in mind, but so far, so good. I'd love to hear what others think if they've tried it.

Thursday, November 4, 2010

PMC Pro - Here we go...

It's finally here! After hearing about this new metal clay product at the PMC Conference this summer, PMC Pro is now available - and my own order is probably somewhere in the middle of the US right now...

Tuesday night I had the opportunity to learn more about this delicious* (OK, not literally) new product. Alison Lee presented one of her fabulous craftcast classes featuring Tim McCreight, with guest comments by Celie Fago, Barbara Becker Simon, and Jeanette Landenwitch. They shared their experiences which provided a lot of insight into using the new material.

Taking a class, (online or otherwise) is a great way to cut your learning curve. I learned some great tips. For some reason, people thought this class was going to be some kind of "infomercial." It was anything but... nobody was selling anything - just sharing their experiences with the material. And we all got the info we needed to get rolling...

Celie Fago's carved ring
Barbara Simon's carved bangle 
One of the things I was thrilled to learn about was how wonderful it is for carving. Both Celie and Barbara commented on how well it worked. I have carved original PMC and loved it. Plus and 3 just don't carve as well. COPPRclay and BRONZclay are good for carving, but when all is said and done, I'm really a silver girl...

Celie Fago tear-away ring
So now I'll get to carve this new stuff and I can't wait! (Hurry UPS!) It takes texture just as beautifully as other versions of PMC - and can accept Keum-boo, though it may be a little more challenging to apply than the fine silver. Celie mentioned that this ring required a little patching... still, it works well enough - and as Celie said "it sticks" which, after all, is the bottom line.

For an hour and thirty minutes we got to hear all about PRO - and ask questions too... there were a lot of questions with about 100 attendees in the class!

Some of the notes from the class are now available on the PMC Guild website.

Just a quick synopsis:
  • This stuff is STRONG! The various strength tests show it to be far superior to any previous PMC formula. You can work thinner without sacrificing strength. 
  • Fired in carbon - 1400ºF for 1 hour (or more, depends on several variables - see the notes). Pieces should be about 1/2" apart (10 cm) and have that much carbon on top and below. Too much carbon will inhibit sintering.
  • Shrinkage is about 15-20%. A bit more than PMC 3 or PMC +
  • Hattie Sanderson added that she sizes rings 3.5 sizes larger to accommodate the shrinkage.
  • Can't be directly mixed with the other clays, but can be joined with the other clays and fired. Requires a shelf firing/carbon firing combo (30 mins shelf 1000ºF; 30 mins 1400ºF carbon).
  • The slip is easy to make - just add water (and lavender oil too - Tim has used this on the greenware as well as the fired clay).
  • As noted above, will accept Keum-boo, no prep necessary.
  • Can be enameled. Using the two-stage shelf firing/carbon firing method is best (per Jeanette Landenwitch). This is not unlike the experience I found with the COPPRclay. Enamel adhered best when it was shelf fired prior to carbon firing.
  • Wash tools between using for other silver clays, just as you would for base metal clays. Do not share sanding tools, as these can load up with material and contaminate your regular clay.
  • The melting point is lower (typical of an alloy) so you have to be sure not to fire with original clay (requiring 1650ºF firing) or use hard solder (flows above the melting point). 
And there's more... when I actually get a chance to play with it, I'll be happy to share what I learn too. Cutting edge stuff - literally, Tim showed a knife he'd made that actually held an edge - pretty cool!

* Barbara Becker Simon's description