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Permalink Reply by StopmoNick on March 26, 2014 at 11:05pm

"Thinner" can be tricky. Depends on what you mean.

I tried one, which was called a Silicone Diluent, mostly to make my silicone pour down a narrow neck hole better.  It did help for that, but it didn't make the silicone any softer.  It appears to have been a silicone oil, and the cast kept sweating oil for weeks.  I'd clean it off with solvent, the next day it was oily again.  And I hadn't even used it on the first two skin coats that I painted on to the mould surface.

The other stuff I've tried is Smith's Deadener.   You add it to silicone to reduce the shore hardness.  I added it to my shore 10 A Platsil Gel-10. It makes the silicone sticky to the touch, so you don't want to use it on the surface skin, just for filling on the inside.  It didn't make the silicone all that much softer, I got a softer mix by getting the Smooth-On Ecoflex 00-30, without the stickiness.  The 00 is a different range of hardness, so despite the number 30 it is softer.  Numbers may even work in reverse, like it is minus 30, but I can't be sure, Smooth-On's website and instructions are not consistent and they don't flat out say which of the 00 range is the softest. They imply it by the order they put them in in one chart, then put them in the oposite order, so who knows.

Smooth-on call their equivalent deadener for the Dragonskin range by a different name but I think it is the same thing. 

I have mixed Platsil and Ecoflex together  when I ran out in the middle of a pour, and they are perfectly compatible, but the hardness seemed closer to the Shore 10.

Shore 10 worked fine for a thin lady, but even 00-30 had too much resistance for a fat guy, I recast with heavier armature wire - 3 strands of 3mm wire for a 10 1/2 inch puppet - and he still can't bend at the waist.  And it's heavy - needed the heavier wire just to stand up.

I prefer the 00-30 now for most things, but I'm mostly just making silicone heads, I only use it for the body if I have to.  Hands are fine in Shore 10A,  possibly even Shore 20, they are thin so the firmer silicone is not a problem.  I use liquid latex buildup on hands a lot, and it is stiffer than silicone, but it works fine.  The finger wires are a high percentage of the total finger thickness.

The best solution for my fat guys would have been Soma Foama silicone foam, but I can't buy it here, and they won't ship it to me either.

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Permalink Reply by Mike on March 27, 2014 at 8:30am

Great information, Nick. 

I'm using Smooth-On Silicone Thinner recommended for Dragon Skin. The instructions say it lowers the mixed viscosity (better flow), increases pot life, and lowers shore hardness. It also shows that a lower shore hardness is softer.

I should have double checked before suggesting a thinner as a limitless means to experiment with shore hardness, because the instructions specifically say to avoid using any more than 10% thinner to the total volume of your mix, and that only lets you knock the shore hardness down about 7%. So you could turn a 30 into 23, but any lower and your silicone becomes less stable and easier to tear. 

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