Can I Use Bisque For Casting A Mold?

[Les]

Hi Everyone,

 

I usually throw one off pieces. But I have 2 already bisqued pieces that I would like to try to make molds from. So my questions are: 1) Should I glaze them first? 2) What mold release is the best to use in either the bisque case or the glazed case; from the point of view of both the originals and the #1 pottery plaster mold.

 

Facts: No undercuts on the originals. Both bisqued pieces were made from Standard Clay #240, smooth white, ^6. I plan to have a 2-piece mold for the vase itself (no foot ring), and a third top piece to serve as a slip reservoir. I make great plaster, having experience with press molds for tiles.

 

Has anyone been in this situation with good outcomes? Could you share your success, or failure, as the case may be?

 

Any thoughts are appreciated,

Les

[Seasoned Warrior]

Actually there are a couple of threads ongoing regarding the subject of bisqued ceramic for molds as well as mold release. Seems the consensus is that Murphy Oil or WD-40 for a mold release. If you use a good release it doesn't matter whether its bisqued or glazed in my opinion. Others may see it differently but to me it's just a process, if you've made a couple of molds, know how to mix plaster then it's just another day at the office and they should be all successes not failures. Good luck! The only thing that I question is making a third piece for a reservoir why not just cast the reservoir into the two halves of the mold, you are going to have to trim it off anyway?

Best regards,

Charles

[Les]

Charles,

 

Thanks for your reply-I will try casting the bisque pieces, and good idea to incorporate the reservoir into the 2 part mold.

 

Les