PMC and lampwork

ChrisM · #1 2006-10-01, 2:29pm

I've never worked with PMC so I don't know the answer to this. One of my bidders asked me this question so I told her I would post it here.

"I design jewelry with PMC. Can these beads be refired and if so what would be my maximum temp. for the kiln. I would be using PMC 3 for these beads."

Also, some of my beads are etched - don't know if this affects it or not.

Thanks in advance!

Chris

Emily · #2 2006-10-01, 5:05pm

If she's asking if she can use your lampwork beads with PMC3, the answer is yes, but she'll have to fire the PMC3 at the lowest possible temperature, which is 1110 F. If her kiln is actually holding that temperature, the glass should be OK. If her pyrometer's off and the kiln's running high -- well, let's hope that doesn't happen. She should be firing for only 30 minutes, which will give her minimum strength on the PMC, so she shouldn't try to do anything structural with the metal. She can't give it the heat and firing time necessary to get maximum strength for the metal without risking the glass getting soft.

She'll need to take the kiln up to temperature slowly, which she won't be used to doing for PMC. If you batch anneal, you can help her work out an appropriate rate, except of course she'll be going to 1110 instead of annealing temp. Remind her that she'll need to cool slowly, too. Unless she fires stones in place, she may be in the habit of grabbing her PMC pieces hot out of the kiln and quenching them in water.

If the kiln holds the right temperature, the etching shouldn't be affected -- but (I'm speculating, here) if the temperature's a little high, that might be the first place it would show.

ChrisM · #3 2006-10-01, 6:16pm

Thank you Emily for all the great information! You're Awesome!!!!

Chris

orodrago · #4 2006-10-01, 6:38pm

5 Stars for Emily's answer - excellent help!
Cheers, Lavender

Raven Wylder · #5 2006-10-02, 3:43pm

So I if I understand the question correctly the bidder wants to take a finished glass bead (annealed) and then put pmc clay (designed etc) on it and refire? So the bead will be fine? Please let me know if I'm wrong?
If not - Wow, Emily that's soo cool! So I can design special bead caps and designs that are attached onto the bead? This might be dangerous - I can't let my bf know I'm starting a new addiction with PMC (I haven't used it before) . Rationalizing: It's just part of the glass addiction. Yeah, that's it. Thanks again!

Emily · #6 2006-10-02, 4:45pm

Before anybody gets too grateful, let me clarify that I'm just going by what the books say, here -- I haven't done it myself (with Moretti/Effetre -- I have fired Bullseye, which is a reasonably safe bet). I've been playing with PMC (PMC+, not PMC3) lately and had my PMC books out when Chris asked her question, so I looked up the firing temps.

WARNING -- I'M BACKTRACKING ON WHAT I SAID BEFORE: I just did some more research on the web, and Arrow Springs' website is giving a lower softening point for Effetre than I'd seen before. I'd heard before that Moretti/Effetre softened between 1100-1200 degrees. Arrow Springs' site gives the softening point as 1050. As we all know, different colors of Effetre have different characteristics, and that's probably the temperature for the color that softens most easily (maybe white or ivory, who knows), but it makes sense to use the most conservative number. Effetre has never been very forthcoming about giving specific info about the characteristics of its glass (it's not exactly COE 104 -- it's just around 104.) Basically this means that if you want to use PMC3 with Effetre, it would make sense to do a test bead before you commit to your whole project, but that's not helpful advice when the beadmaker and the PMC user aren't the same person. "Use Bullseye" isn't exactly helpful, either.

DreamMuse · #7 2006-10-02, 9:09pm

I haven't fired PMC and beads together, but I have done both separately. The other thing you'll want to remind her of is that some colors of glass will be affected by firing them with silver. White is the worst, and will turn yellow. Ivory and some clear are also problems - so if it's an encased bead there's a chance it'll develop a scummy surface near where the silver touches the bead.

ChrisM · #8 2006-10-03, 5:28am

Thanks everyone for all the great responses. I wrote back to the bidder with the ideas given here and also offered her a test bead to try it on first. She said that it sounded too risky to try and that she wouldn't be able to do it anyway with her pre-programmed kiln. (She was very grateful for all the info from you guys).

But the idea is really intriguing to me. If anyone tries it, I'd love to see pictures!

Thanks again,

Chris