[annbclay]

Is it possible to make a plaster hump mold of a straight sided, deep Tuperware type container? I've tried it once, using Murphy's oil soap as a release agent but I can't get the plaster hump out without cutting off the plastic bowl. Any tips?
Ann B

[Linnet]

I use something called 'soft soap', not really a soap, but must be similar to what you already use. I've heard of some using the can spray cooking oil but I have never tried it. Good luck

[timj219]

annbclay, on 31 March 2010 - 10:10 AM, said:

Is it possible to make a plaster hump mold of a straight sided, deep Tuperware type container? I've tried it once, using Murphy's oil soap as a release agent but I can't get the plaster hump out without cutting off the plastic bowl. Any tips?
Ann B

No art without sacrifice. The tupperware will go to its reward knowing it gave its life in a good cause.
Petroleum jelly might do the trick.

[Zygote]

Strait sides = friction and drag.
You can try "Burping" the mold. This is where you use compressed air to pop the seal between mold and master.
Other wise, cut the bowl.

[Carl]

If there are no undercuts, petroleum jelly should work... at least it seemed to work well for making bronze casting molds from plaster. Normally one uses something with a slight inward slant to make releasing a bit easier.

[Linnet]

Maybe wrap tightly kitchen cling wrap without creasing over the surface of the tupperware, just a thought.

[Brenda]

annbclay, on 31 March 2010 - 03:10 PM, said:

Is it possible to make a plaster hump mold of a straight sided, deep Tuperware type container? I've tried it once, using Murphy's oil soap as a release agent but I can't get the plaster hump out without cutting off the plastic bowl. Any tips?
Ann B

I use baby oil. It hasn't failed me yet.
Brenda

[Linnet]

This actually sounds more like a slab construction method to me.

[annbclay]

thanks guys, I'll try again. This one will have to sacrifice it's tupperware though. As you said, the price of art!

[Cindy in SD]

Just a thought, but I like to use bisque molds. That is, if you're hand building--if you're pouring, then never mind . . . . I just throw a piece the size and shape I want, then trim the outside to be nice and smooth. That way I can coil/puzzle/pound my clay over the outside or make a smaller piece on the inside.