Help release mold parts

kenno3 · Post by **kenno3** » Tue Dec 20, 2011 11:11 pm

Hi can you please help me? I made a 2 part silicone rubber mold using Oomoo 30.
After it was cured, I sprayed the first part with "Castin Craft Mold Release and Conditioner." Then I poured the 2nd half of the part. But after curing, the 2 parts stuck together and I had to cut apart the rubber to get my master out.

1) Does "Castin Craft Mold Release and Conditioner" not work on Oomoo 30?
2) Or if anyone knows if it works, perhaps my coat was too thin? I sprayed it twice, then rubbed it in using a small brush.

3) Or could it be that the rubber fused together because part 1 had some slightly unmixed rubber at the top (but dry), which made it stick to part 2?

I searched the forums and read about using Vaseline with mineral spirits, but first I would like to know if the "Castin Craft Mold Release and Conditioner" works or not.
Thank you for any quick replies. I'm going against a deadline and the problems have already set me back.

Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Tue Dec 20, 2011 11:34 pm

The mold release you used is for conditioning the mold to let go of cast parts.
It is not meant to prevent a second pour from sticking to the first half.
Petroleum jelly, or wax would have been a good release for mold halves.

You will have to carfully cut the mold apart.
You can still create "keys" as you cut, so the mold will go back together nicely.

kenno3 · Post by **kenno3** » Tue Dec 20, 2011 11:40 pm

Thank you for the info.
I wont be able to cut the mold into 2 (usable) parts since its in-closed on all sides and I cant see when Im about to hit the master part. I already cut out the master part and damaged it with scrapes from the blade.

Ill try Petroleum jelly.

USS Atlantis · Post by **USS Atlantis** » Wed Dec 21, 2011 3:18 am

Also look for something that specifically says "Rubber-to-rubber mold release"

There are a few out there, and this is what you wanted to use when making the two-part rubber mold

If you do use the petroleum jelly - use a VERY thin layer - too thick and the mold seams won't join properly when you're ready to pour resin and it'll leak (don't ask me how I know this)

kenno3 · Post by **kenno3** » Wed Dec 21, 2011 5:55 am

Thanks. Im going to try mixing 1 part paint thinner and 1 part Vaseline. That will work correct?

My mistake, I thought the mold release I mentioned, would work, when I ordered supplies weeks ago. But I wont get it in time if I order now.
Anyone know of an in-person-store where I can buy "Ease Release 200 - Aerosol Can" or a rubber to rubber mold release (besides Blick)?

I bought the Oomoo from Blick but its too far of a drive for me.

modelnutz · Post by **modelnutz** » Wed Dec 21, 2011 5:25 pm

Mineral spirits is the solvent of choice when thinning vaselene