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Discussion Starter · #1 ·
okay...............sighs.............

I could use some mold making help.

I tried to make a silicone mold of a skull. I did not use any type of release (I was told on another list that releases were not necessary for silicone....I now have a stuck skull.............lol...........

I have virtually no experience with mold making, but I want to try all the different types. Over the next few days I will attempt a POP mold, and I would like to try making a plastic mold.

Any advice would be appreciated.

Hex
 

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This sounds like it'll be right up Vlad's alley of expertise. I want to try molding myself someday.
 

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Hi Hex. The links are in the How To section. But first tell us what happened with the silicone mold. What was the skull made out of? Is the silicone stuck to the material, or held on by undercuts on the original?
 

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Discussion Starter · #7 ·
Hi Vlad!!

The skull I used looked very much like the one in your paper mache how to. Not the Bucky skull, the other one.

I had read online dozens of how to's on making the mold; Almost everything I read said you did not need a release for Silicone. In retrospect, I think the two problems I had werre the undercuts (I had NO idea about that, go figure, after reading all that I read) and the need for a release agent.

The skull I used was probably a styrofoam skull, but it had a very thin coating over it, maybe vanillacryl. Anyway, it pretty much locked the lower jaw into the mold.
(failure #1)

I finally got it out, filled my mold with spray foam insulation to make a semi deformed dupe, and IT got stuck!!

(failure #2)

But I have not given up!!

I will succeed!!!

Hex
 

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Hi Hex.That's the key, don't give up. If you follow the procedures on making paper mache skulls in my how to, it will show you how to fill in the undercuts using plasticene clay. You WILL need a release agent if you're going to try to use spray foam inside either a silicone or latex skull mold. Try using either paste car wax, or better yet, paint on some dish washing detergent.
Also, I find that I can get away with the undercuts if I make a slice up the back of the mold before trying to remove it. Then peel it off like a banana skin.That is also shown in the how to's. Just use duct tape to close the cut before making the next casting.
Let me know how you make out. Vlad
 

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Discussion Starter · #9 ·
I have another question about polyester resin. Have you worked with it much? I have read that it is a versatile material, that you don't need a mother mold if you make your mold out of it.

I was wondering what type of casting I can make from it. Do you know if silicone sticks to it?

Thanks,
Hex
 

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Hex, Whenever you have two different materials coming into contact, the only true answer is to experiment with a small patch first. Different manufacturers of similar products all could have material that varies in some way. But no, they shouldn't stick to each other.
As to not needing a mother mold if you make a mold of polyester resin, yes, you would still need a mother mold if you were casting expanding foams into it, like you seem to want to do. The expansion of the foam would force the two halves apart otherwise. A resin mold would be inflexible, and unless you were casting tapered candles, it would have to be a two part mold to be able to free the casting later.
As to what you could use to cast in it, I would think anything, as long as you use the proper release agent.
Here's a neat site to look through on some of the basics, and materials available. I haven't dealt with them, but lots of good info. Vlad >>>>>>>>>>>>

http://www.smooth-on.com/default.htm
 
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