Feb 24, 2012, 10:37 PM - Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
I know sulphur based clays inhibit silicone from curing, but just how sensitive is it? I routinely used sulphur clays (I bought about 30 lbs years ago that I don't want to ditch) for sculpts, but now I have a bit of sulphur free I need to cast in silicone. Will the remnants of sulphur clay on all my tools be enough to cause problems? And if so, what would be best to clean them with before using to prevent cross- contamination?
Last edited by BornKilr; Feb 25, 2012 at 8:38 AM.
Feb 25, 2012, 8:38 AM - Re: Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
I'n hoping to work on this today if anyone can answer this.
Feb 25, 2012, 9:01 AM - Re: Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
You don't mention what your tools are made of. If you're using metal or plastic, you could run them through the dishwasher. Wood tools can be scrubbed with a soft brush and dish soap.
If you keep your tools fairly clean, you probably won't have any problems from microscopic residue. But, it seems to me that it would be worth a little time cleaning to protect your work and mold investment.
Feb 25, 2012, 9:39 AM - Re: Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
You should also be able to use rubbing alcohol to clean your tools. Especially if they're metal. I've done prosthetic makeup for a while and know that platinum-cure silicone is highly susceptible to sulfur. I haven't used tin-cured silicone so I'm not sure what the effects of sulfur would be on that. But I agree, it's better to be safe than sorry.
Feb 25, 2012, 9:44 AM - Re: Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
Acetone or Naptha should clean any residue from your tools. As for using the clay, I would try giving it several liberal coats of a clearcoat acrylic, then a coat of mold release, then a coat of cure promoter. Do a small scale test after that and if it STILL doesn't cure, pack it in.
On a part that I knew would cause cure inhibition -
I sealed it with thinned down epoxy.
3 coats of primer
3 coats of acrylic clearcoat
2 liberal coats of challenge 90
And it STILL did not cure against the surface of the part. The key is to making a physical barrier between the clay and the silicone, but even then it is hit or miss. Sometimes its just not meant to be.
Feb 25, 2012, 9:58 AM - Re: Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
It's only a problem with platinum silicones, if it's tin, no problem.
If your using plat silicone then seal your sculpt as mentioned about and when moulding, brush in a thin layer of silicone and force cure with a heat gun. The less time the silicone is liquid, the less likely it is to contaminate. Then just continue to make your mould asmyou would normally
Feb 25, 2012, 10:32 AM - Re: Sculpter's Help NEEDED!! Silicone mold-Sulphur issue
Well, that in itself should take care of the problem. Its tin-based. I didn't know there was a difference with the sulphur issue.
I have a mix of tools; metal loops, plastic and wood scrapers and dental tools. Its a small piece so I should only need a few of them. So I'll scrape and wash them all before I start.
As of the project, I'm sculpting vampire-bat appliances (loosely based on the look of the creature from the "Bram Stoker Dracula" movie.) Its for a WW1 German Vampire soldier from the comic "Baltimore: The Plague Ships"
The small piece I'm needing to sculpt and cast is the spike for the pickelhaube helmet I'm making.
Thanks for the quick help everyone. I hope to get the done today and cast tomorrow. I'll have a WIP thread for the costume up when I get some pics.
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