reusing plaster mold

[east-coast-jacques]

Hi all,
I am just starting my sefl formation on glass fusion thanks to this site and all your information on the forum. I have done ceramic for quite a while but also havent toutched it for a while. Now my question is: If I make a mold of plaster and chamotte(grog) can it be reusable and how much. If not, would you guys have a better solution for me?

[Ron Coleman]

Heat destroys the chemical composition of plaster and it will start to fall apart during the first firing, even with grog added.

Since you know how to work with clay, try some raku clay and form your molds and then bisque fire them. After bisque firing add some kiln wash and you will have a mold good for many trips to the kiln.

Ron

[slats]

Ron advice pls.....Just make my own molds with raku (you inspired me) they have been sitting lightly covered with plastic but dont seem to be drying out? How long should this take. It is cold in my garage....Ill have real mold soon......green Then when I do fire...can u give me a firing schedule for jen ken 24".........

[charlie]

Ron advice pls.....Just make my own molds with raku (you inspired me) they have been sitting lightly covered with plastic but dont seem to be drying out? How long should this take. It is cold in my garage....Ill have real mold soon......green Then when I do fire...can u give me a firing schedule for jen ken 24".........

you need some air circulation and a way to export water.

dry them on wallboard, or cover with newspaper and replace daily.

if it's humid out, it could take weeks to dry them.

firing schedule i use is

400 850 0
100 1050 0
400 1650 30
off. cool to room temp without opening.

[Bert Weiss]

Hi all,
I am just starting my sefl formation on glass fusion thanks to this site and all your information on the forum. I have done ceramic for quite a while but also havent toutched it for a while. Now my question is: If I make a mold of plaster and chamotte(grog) can it be reusable and how much. If not, would you guys have a better solution for me?

Jacques

Ron's suggestion is a good one. For a more complete description of mold making techniques for glass get Boyce Lundstrom's book "Glass Casting and Mold Making, book 3" Click on the Whitehouse books sponsor link.