Casting multiples from the same mold?

[Gale aka artistefem]

Anyone casting multiples from the same mold?

I just had a potter friend make bisqued open face (no undercuts) clay molds for me, so I can cast the same basic shape more than just once.

I'll use these basic shaped glass forms in differing ways to make each piece a one of a kind.

Anyone have experience with using bisqued clay forms this way?

[charlie]

well, i use bisqued drop rings, bowl shapes, etc for glass. they hold up well after kiln washing them, so i suppose they can be used for molding too.

[Bert Weiss]

Anyone casting multiples from the same mold?

I just had a potter friend make bisqued open face (no undercuts) clay molds for me, so I can cast the same basic shape more than just once.

I'll use these basic shaped glass forms in differing ways to make each piece a one of a kind.

Anyone have experience with using bisqued clay forms this way?

Gale

If your clay molds work, you got it. If they don't the coolest way I know of to make multiples is a rubber positive. You can cast infinite plasters using it. Smooth-on makes one formula with a built in release agent. You can make a rubber positive from a rubber negative or plaster negative.

[Gale aka artistefem]

Thanks, Charlie & Bert. I guess I didn't explain very well what I'm trying to do I too, successfully use slip cast ceramic molds for all sorts of glass slumping (unless I take it all out of the kiln too soon - LOL).

What I'm trying to make with these clay molds is a repeatable cast cup shape.

The clay forms were thrown on a potters wheel. The upward draft of the cup is fairly thin - about 1/4" thick and the clay base at the bottom of the cup is thicker walled - about 1 1/2 to 2" of thickness to provide a stable base for the mold shape.

Basically this is an open face mold. I'm filling the interior of the fritted mold with carefully packed whiting so the frit cup wall won't slip and slide down the mold wall.

Do you see any problem with the glass heating/annealing differental between the thicker and thinner areas of the clay mold?

[Gale aka artistefem]

PS. Bert, I use the rubber mold materials as well. I'm just now taking a rubber mold of the cup appendages that I carved in clay.

Don't want to have an OOPS! and lose all the hours I've spent carving the original forms. This would suck BIG TIME!!!

[charlie]

Thanks, Charlie & Bert. I guess I didn't explain very well what I'm trying to do I too, successfully use slip cast ceramic molds for all sorts of glass slumping (unless I take it all out of the kiln too soon - LOL).

What I'm trying to make with these clay molds is a repeatable cast cup shape.

The clay forms were thrown on a potters wheel. The upward draft of the cup is fairly thin - about 1/4" thick and the clay base at the bottom of the cup is thicker walled - about 1 1/2 to 2" of thickness to provide a stable base for the mold shape.

Basically this is an open face mold. I'm filling the interior of the fritted mold with carefully packed whiting so the frit cup wall won't slip and slide down the mold wall.

Do you see any problem with the glass heating/annealing differental between the thicker and thinner areas of the clay mold?

i made something similar. i threw a small, shallow bowl on a wheel. it was pretty thin on the edge (maybe 1/8"), and had a thick bottom (maybe 1"), after throwing it. i then bisqued it after drying it for weeks.

the first time i used it, the glass blank was fractionally over the edges on two opposize sides (it wasn't round). on cooldown, the glass shrunk more than the clay, and crushed the edges. however, the rest of the bowl worked out just fine, in that the glass came out just fine. i don't think that there's any difference for using frit rather than a blank.

[Steph Mader]

Gale,

If you're packing frit the typical pate de verre way, Delores is a good person to talk to. She's got a lot of experience with this technique & firing schedules for different types of pate de verre.
Steph

[Gale aka artistefem]

Thanks Steph..........I do visit with Delores every now and again about this type of work. She's graciously helped me out more than once.

Hope the right pieces of the cosmos line up so I can, one of these days, take a "real" class from her.

[Delores Taylor]

Thanks Steph..........I do visit with Delores every now and again about this type of work. She's graciously helped me out more than once.

Hope the right pieces of the cosmos line up so I can, one of these days, take a "real" class from her.

I'll put you up at Casa de Taylor if you come my way. I used to make a cast childs hand from clay bisque but found the clay really caused bad devit problems and those tiny little fingers were a bear to get cast right not to mention invested in the first place. But I'm drifting. I think I'd prefer to see you go the rubber model to plaster/silica investment. If you want sugar crystal your core material should be OK but if you want alabster go male/female plug mold with a reserve cup at the base of the cup and cold work when done. The best book that covers this process to a fine science is the Art and Technique of Pate de Verre which can be found at Whitehouse Books, Julie will order if it's not in stock (nice folks).

Thick to thin is problematic to say the least. You sound like me taking on the nightmare casting first. Yes it can be done but it's a head banger as the glass expands and contracts during cooling put those thick/thin bits at risk of being shocked to a sad state of cracking. Unless the thick to thin isn't radical different.

What's that mean: go slowwwwww and you should be OK also go painstaking slow during the strain point on the way down or it's heart break city. Go #1 pottery/200 mesh silica by weight slake into water until dry riverbed (this is typically a 60/40 or 70/30 sort of weighed plaster to water ratio).

You have my e-mail if you run into a snag.

Happy Casting

Delores

[Gale aka artistefem]

Thank you Delores.......I'm still in the experimentation stage with the visuals and appropriate mold material.

My initial plaster molds gave me some problems (not sure of the age or viablity of the plaster). If these clay cup forms don't work, I'll go back to my 50/50 mix with a fresh bag of plaster.

I'm making the set in a series mode, using the same glass & colors - just in differing ways for each piece. Some of the cups in sugar and the others in alabaster.

I'll email images and thank you very much for the Casa offer. I will get out your way to study with you one of these days (& maybe - once our new "big-boy" kiln is built - perhaps I can interest you in coming out to teach a workshop for us here in St. Lou-land on the Miss???).

[Delores Taylor]

Thank you Delores.......I'm still in the experimentation stage with the visuals and appropriate mold material.

My initial plaster molds gave me some problems (not sure of the age or viablity of the plaster). If these clay cup forms don't work, I'll go back to my 50/50 mix with a fresh bag of plaster.

I'm making the set in a series mode, using the same glass & colors - just in differing ways for each piece. Some of the cups in sugar and the others in alabaster.

I'll email images and thank you very much for the Casa offer. I will get out your way to study with you one of these days (& maybe - once our new "big-boy" kiln is built - perhaps I can interest you in coming out to teach a workshop for us here in St. Lou-land on the Miss???).

Sounds like fun keep me posted.

[Lauri Levanto]

I have worked with ceramic molds, both for slumping and casting.

I have used white low-fire clay with 25 percent of grogg.
It needs kilnwash regularly, but have lasted over 20
castings w/o significant wearing.

I have on web only one photo. It is a slumped
float glass piece.

http://www.netti.fi/~laurleva/Glass-relief-1.html

-lauri