Monday, September 19, 2011

More Thoughts on Silicone and Resin

When it comes to silicone and resin there are 3 companies I noticed have been mentioned a few times by BJD makers. (There are more companies out there so if you are looking for silicone rubber and urathane resin, look around.) They are Smooth-On, Alumilite, and Polytek. Since I prefer to buy the silicone and resin from the same company, if possible, I decided to go with the company Smooth-On since their resin Smooth-Cast 305 is recommended.

Of the Smooth-On Silicone Rubbers offered, a few have caught my interest. Mainly Mold Max 30, OOMOO 25/30, Mold Star 30, Dragon Skin 30, and Sorta Clear 40. There are two categories of silicone rubbers: tin-cured and platinum-cured. The shelf life of tin-cured is not as long as platinum-cured. So if I was making a mold that doesn't need to last years, tin-cured should be fine. But if I want to make a mold of a more valuable sculpt, I would go with a platinum-cured silicone rubber. Of the rubbers I listed above, Mold Max and OOMOO are tin-cured. Mold Star, Dragon Skin, and Sorta Clear are platinum-cured.

So which one to use? Without a pressure pot, I need to use a silicone rubber that has a very low viscosity, which is the OOMOO line. The difference between the OOMOO 25 and 30 is the pot life, demold time, and shore hardness.

If I had a pressure pot and wanted a platinum-cured rubber, I would want to try the Dragon Skin 30 or the Sorta Clear 40. I am very interested in using a transparent type silicone rubber since this would allow me to see through the mold for cutting.  But for now I have to settle with what I can use without a pressure pot.

Since I have no silicone rubber molding making or urethane resin casting experience I decided to purchase the Smooth-On Pourable Starter Kit from DickBlick to give it a try. This kit comes with a trial size of OOMOO 25, Smooth-Cast 300, Ease Release 205, plus extra. At $50 it is a good start to have all you need to try molding and casting. I will be posting more about it when I get a chance to try it out.

I failed to get Arisu's head done this weekend but it should be done by the time the kit arrives... I hope.

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