Silicone Mold Fails
I cut a mold from PVC and used the product Chef Rubber Silicone. The silicone never cures where it touches the mold surfaces. I then tried cutting mold in MDF then painted the mold, same result. I tried with a mold release spray as well.
Has anyone had success cutting a mold cavity and making a silicone mold (Food Grade Silicone)
maybe its my brand of silicone
Ideas ?
I tried using a silicone mold product from Tap plastics for the first time. I printed the positive and the mold walls with PLA and then spray primed the surfaces with sandable primer and sanded them to make them smooth. I sanded back down to the PLA in a lot of areas, but where there was primer, the silicone did not set. I re-read the container and it had something like:
“[Here is a list of things that will inhibit the curing process], and some masking tapes and some pigments and dyes.”
So, like, other dyes? Like the things that are in almost EVERYTHING?
Oh, never mind. I get to find out at $45.00 pint.
I feel you. I guess go back to the store (if that is where you got it) and ask about non-reactive mold making products?
It might be your mixing technique. You need to really mix the hell out of that stuff, for like 3 minutes or so, scraping the sides and bottom of the container etc.
Smooth-on makes several excellent food safe silicones that you might try. Plus if you call them for technical help, they are the nicest and most knowledgeable people on earth. And they have lots of YouTube videos on how to do stuff.
I made a mold for a crazy owl cake using this one:
This guide may also be useful, it was for me:
http://lcamtuf.coredump.cx/gcnc/
However, do bear in mind that he is making tiny robots, so the strength and rigidity of his final parts has to be very high, which means he is using extremely dense silicone - if you bought what he’s using, you would never get the food out of your mold intact.
Like the poster above, I’d also suggest the Smooth-On products. Ratio and proper mixing are critical. I only use a scale, mixing by weight. Having a vacuum chamber to degas can be beneficial. I haven’t personally had many issues, but I’ve helped a number of people get setup, and I’ve later assisted them diagnosing their problems. Using a pigment/dye that isn’t compatible, improper mixing, and a lack of care when portioning out materials have been the primary failure producing errors. The material can also go bad. I separate out my old stuff and use it for experiments, personally haven’t had a failure yet.
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