Mold Making Help/Advice -- What clay to use?

[brianna]

I am new to this site, as well as to mold and prop-making.I hope this is the right place to ask this question, if not I will move it if its wrong!
I want to cast small sculptors, but I am wondering what clay to use?

I researched that with a 2-part mold, you fill the edges around the mold with a oil-based clay such as Monster Clay. However, what if I have made sculptors out of monster clay or basic ceramic sculpture clay? Is it still possible to use these materials and cast of mold of them? If so, how would I go about this as I realize the oil based clays do not dry. What clays are best to sculpt with to make a mold out of?

Thank you all so much! I am planning on building a large-scale replica of Audrey II from Little Shop of Horrors and I'll be happy to update any progress on here.

 

[cavx]

Welcome to the forums.

Molding and cast generally requires you to have a master part that mold in silicone. This master part can be made from pretty much anything so long as it does not inhibit the curing of the silicone. Once your mold is made, you can cast your parts in either a resin or a plaster.

If you have never made a mold before, you might want to take on a very simple one part or open back mold to see how this works out for you.

AFAIK, the only time you would create a mold in a hard ceramic is for make up appliances like a false nose (EG a witch's nose with warts) and then the rubber used is quite a specialty item.

HERE is a link to my blog where I documented how I made a 2 part mold for a complex 3D part. The method I used is different to how most would cast such a part because I made the outside of the mold like a bowl so I would not have leaks.

 

[Knightjar]

Either clay is fine Use whichever you're more comfortable sculpting with. Seal your sculpt with a few coats of acylic lacquer and you can even use the same clay for your mould-making walls; it will separate cleanly from your sculpt thanks to the laquer.

 

[Shipbrook]

Seal your sculpt with a few coats of acylic lacquer and you can even use the same clay for your mould-making walls; it will separate cleanly from your sculpt thanks to the laquer.

Does that work better than mould-release sprays? (I'm gearing up to cast something for the first time in a few years, so as long as I'm replacing all my expired bottles of silicone and resins, I might as well get the best mould releaser too.)

 

[Knightjar]

It's not an alternative to mould-release spray. Sealing any clay is usually a good idea to make sure nothing inhibits the silcone from curing. The lacquer also protects your sculpt from minor accidental scuffs while you're making the mould. You can seal it with acrylic and then spray it with mould release. In this case though, it's just for making sure your clay walls for mould-making don't end up attached to your sculpt.

 

[pitchforknumb]

I always use water clay, em-210. It is a lot faster and easier to work with than going the oil clay route. Plus much cheaper. I was able to put this clay wall down in about an hour. It would have easily taken twice as long if I did it in oil clay.