Make a mold??

[glassman52]

My fusing has been limited to cabs. (for pendants and earrings) and small slumping projects as I have yet to get a decent kiln. My question is can you make your own ceramic molds for glass? I have used this stuff >http://www.delphiglass.com/fusing-supplies/fiber-paper-shelf-wash/12-square-vermiculite-board but it's like carving a ceiling tile, messy and not good for detail.

When I finally do get a kiln there are things I want to make that I have not seen molds for.

[Stephen Richard]

Yes you can make moulds from ceramic materials.  Some of the considerations in making them are given here:
http://glasstips.blogspot.com/2011/04/complications-in-moulds.html
Also you should make the walls of the mould as thin as possible to avoid excessive heat retention.
You can also make master moulds from other materials such as RTV rubber, from which one off refractory moulds can be made.

Found moulds can also be used:
http://glasstips.blogspot.com/2010/10/found-moulds.html

Good luck and have lots of fun

[Ian]

HI glassman52
Have a look at General topics, Tutorials and Educational, Glasswork related,Making clay molds. It will give you an idea of how to go about making glass slimping molds.
You will have to fire the clay molds in a ceramic kiln as a glass kiln is not hot enough.
Ian

[Glassic]

I have to make a draping mold this Winter, do I have to consider clay shrinkage? It's for a lamp and the curvature needs to match that of the lamp mold.

[Stephen Richard]

I have to make a draping mold this Winter, do I have to consider clay shrinkage?

Yes

It's for a lamp and the curvature needs to match that of the lamp mold.

Since the panels are likely to be light, try using ceramic fibre hardened with collodial silica.

[Glassic]

Thanks Stephen, will do my homework on that!

[Ian]

Glassic
To answer your question about clay shrinkage.  I work on making my master that the plaster mold is made from +- 10% bigger than the finished glass panel. I used clay because I had to make curved panels for an existing slumped lampshade that had three broken panels and the clay is more accurate than fibre and besides they are permanent
Ian

[Rebecca]

I use Moist Pack for lamp panels.  It is fiber with a hardener.  I just press it to a good lamp panel and let it dry.  Then coat it with kiln wash and it is good for many, many slumps.  (I don't know how many because I have never had one to fail.)  It doesn't have a perfectly smooth surface, but it doesn't matter unless you let the temperature get too high.  Then you probably have other problems besides the slight dimples that the glass takes from the mold if you go too high.

Rebecca

[Glassic]

Thanks Rebecca, Nancy told me to ask you! This post brought the topic to the top of my list! I'm wanting to make the Odyssey Bamboo shade and the leaves need bending.

[Rebecca]

Cool, Yvonne!  I hope you will post pictures as you work on it.

I had accidently collapsed the menu and didn't see this when it was first posted.

Rebecca

[Glassic]

I don't know how to post pictures of cussing!

[Rebecca]

I don't know how to post pictures of cussing!

HAhahahaha!  You will have to post videos.

Rebecca

[Ozzieglassie]

A glass kiln should be hot enough to do a basic bisque fire, You don't need to go to Stoneware temps for a mould. Just be sure to fire slowly enough.

[Glassic]

This is all good info, my little Caldera will fire ceramic. I might just have to unpack it!

[Amber]

I can second what Ozzieglassie said, you can bisque in a glass kiln :). Potters take it higher to burn off organic materials because they end up glazing their works in a subsequent fire, but it's something us glass folk don't have to worry about *woohoo*. I just started making my own clay molds, proper wedging, drying and a slow fire are the best tips!