How to Create frit casting mold - Help!

[Teknoron]

Sometimes I think this place is a blessing and a curse. A blessing that it has some many incredible people with vast knowledge and a curse because when I learn something new I go full steam ahead. Ok so here is my issue, I bought this mold for frit casting and love it to death. I messed up was not watching what I was doing and bam, broken toast! I contacted the place where I bought, I had bought the last one they ever had, they tried reordering it, 8 months ago and they still keep telling me it is on indefinite back order. Being a computer genius that I am, which I was a glass genius more often than not, I tracked down the shop who makes the mold, they at this time have no plans to make the mold???? WTH???
So what I am looking for is a site, direction’s, anything on how to create a frit casting mold. I have seen a few articles but every time I have tried something it doesn't work, I come here and usually someone left a step off, which is why I came here first. I have made many silicone and resin molds, and it takes a lot of time and effort to do the freeze and frit molds, not to mention I can make a mold the same size as the bottom of my tabletop kiln and have more usable space. I have allot of pieces that I have made with silicone, sculpey and with resin that I think would look cooler in glass. So if some could jut point me in the right direction that would be awesome!!!!

Thanks!!!!

[Teknoron]

I have read about using slip to make a mold, my idea would be to make several sculpey pieces in a box the size of or near the size of the bottom of my kiln and pour the slip in, let dry and pull the pieces out. The other method I read was with clay, press in your hard object and bake the clay then use it for frit however the exploding part gives me caution, I am looking for the simplest way to make the molds. If they clay is better then what clay and what do I need to do.

[Judd]

Buy plaster-of-paris, make your mold from that. I have had great success mixing play ground sand with the plaster. It makes the molds much more durable. I have gotten as many as 10 firings out of one plaster mold - but it was a simple, open-faced mold.

[rosanna gusler]

a picture of the broken mold would help. rosanna

[Teknoron]

How many firings can i get out of using clay if Plaster of Paris is around 10. Just thinking that if clay is an option, i could make a 6-7" square slab, knead it to get all the air out of it, then press my piece in which would be maybe 1/2" deep, which would still give me a 1/2" of sturdy to make it pretty durable. This would give me between 9-12 pieces each firing. The article that I had read they were using Amaco clay #25, is this the best clay to use, is there a better clay? I really do not want to be recasting a mold, well unless i drop it, again... However I do want to be able to make replacement molds if I need to, esp if I get a bigger kiln.

Again thanks for any heads up something I am not taking in consideration or some good advice.

[Teknoron]

Also, noticed that all my frit molds are pretty much hollow on the bottom. is this to save money and material? What i want to know is that if I take a 6"x6" slab 1" thick, then bake it to bisque, this should be a sturdy, heavy mold. might take more time to cool down, will this work?

[haleybach]

I wonder about the hollow bottoms too.
Could be to allow more even heating and cooling.
Might also just be because they are slip cast.

I've never used Amaco #25. Different clay bodies are formulated for specific properties, if you have a local clay supplier nothing beats going in and asking questions in person. If not I'd call one of the bigger online retailers. Tell them what you want to do, they will guide you to an appropriate clay choice.

[Morganica]

Clay/bisque slumping molds are kept as thin as possible to promote even heating and prevent overinsulation. You also try to make the walls of any ceramic construction as even as possible to promote even drying/shrinkage/firing.