Clay Optic Molds?

[Eileen]

Has anyone tried using clay to make optic molds (fired to bisque)? I was reading that I could make textured marvering surfaces to roll beads on, and got to wondering if it would work for optic molds also.
I'm assuming I would need to soak the mold like it says to soak the textured clay marver, but I'm wondering if I need to know anything special about shaping. Common sense tells me that the shape needs to allow the glass to come out without obstacles (like U or V, not curvy) but any other advice?

I did try a search, but couldn't find the answer, so sorry if this is old hat.

[RSimmons]

My first thought is that the shape of the optic mold would be a problem. A flat textured marver can take a certain amount of expansion but the circular shape of the optic mold might make it more likely to crack from the sudden heat. Could be wrong, but that's my first take on it. Anyone else tried this?

Robert

[Eileen]

Maybe I'll just give it a shot. I've got lots of clay, but I sure hate to waste glass, LOL.

[scoutycat]

i think there's some kind of additive that they put in crucibles and molds for slumping, you might want to check that out. Altho, i suspect you'll find that the glass sticks too much to make a clay optic mold useful. A flat marver doesn't usually require the same pressure and long contact an optic mold does.

[Eileen]

Good to know. I've not used an optic mold yet.
I've made molds for slumping, but they have kiln wash put on them so the glass doesn't stick (or kiln paper).

I didn't know if the steam would work for that or not. Maybe I'll just make a very small one so I don't waste too much glass if it sticks in there.

[ben david]

Eileen, I think you mentioned the main potential problem: sticking. The kiln wash coatings that are used to prevent sticking during slumping are not very durable, and tend to flake with time.

There are easy ways to make optical molds of metal or wood, without the problems of ceramics. I've seen these brought into the offhand glassblowing studio I work at:

1) Drive long nails into a wooden base.
2) Cut fins out of thin metal sheet, and embed them in a cast concrete base.
3) Various constructions of wood, which are soaked in water before being used.

No sticking problems with any of these.

If you are talking about typical bead/flamework size - there is probably nothing easier than driving a circle of nails into a block of wood, and then bending them out to a cone.

[yellowbird]

I have not tried this but I think you want an open body clay like raku.

I'm curious to hear what happens good luck

[Bead Man]

i took a class with michael barley several years ago. during this class he had discussed using a handmade clay mold for shaping some of his beads. perhaps he might have some information that wouls help if you were to contact him.

[Eileen]

I missed seeing these replies (still learning my way around the site I guess) but thank you all for your input. If it works I'll report back, I've had "the crud" for a few days, but maybe will be able to get out & work a bit tomorrow.