TC 5110 Cure Inhibition
I am not sure if this is the right category, but I have run into a bizarre problem that I have not been successfully dealing with. I am working on a little "cable" controlled puppet, and I cast the skin in 5110 Platinum silicone. I had to cut it down the back to insert the armature and mechanism, and now I'm trying to seal it up and patch the seams. Only now, whenever I apply new material to the original casting, it will not cure. I called the manufacturer BJB for help and I took his advice but with no success. I mixed larger batches for a greater margin of error, I tried a batch without pigments or thickener, added heat, mixed parts A and B for over 3 minutes, and let it start to kick before applying. The same batch will cure if left in the cup or brushed into a different mold. I was using a silicone adhesive to glue it back together, so that was my first culprit, so I cut all that away (it bonded very well). The skin was still a little tacky, so I had been blasting it with a space heater for several consecutive hours. The tackiness is resolved, but the cure inhibition is still there. I have scrubbed it down with acetone, 99% IPA, and Naptha. It has to be something on the puppet that is inhibiting the silicone, but I can't understand what it could be. The original casting is a little old by now, it took forever for me to troubleshoot the mechanisms, but the issue is not only that its not bonding but it is falling to cure properly to begin with. I have no idea what to do next.
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Comments
The advice on mixing a larger batch is solid, as sometimes small batches of silicone can have trouble curing since the margin for error is so small.
Cleaning it with mineral spirits was also a good idea, so you are at least trying all the right things!
What was the original sculpture in? I'm wondering if the mold is somehow contaminated since your second casting is having inhibition issues.
/Chris