Moldmaking Which clay to use when making molds?

Generally sulphur based clays react badly to molds... or atleast, that's what I've read.

 

I just use whatever ceramic clay I have and I haven't had a problem. The tutorials the suppliers put up usually use modeling clay, which I've decided to try out on my next mold, but mainly since I have a fair amount of that around from my childhood. Any regular gray clay should work fine though, I think. I haven't tried it with a red or white before, but I think in this instance, whatever is handy and cheap is good.

 

Keana:
sulfur reacts with Platinum-Cure Polyurethane. When making silicone molds, you should avoid latex, I think.

 

sulfur clay reacts to any kind of silicone from what the sheets from Smooth-on say. Best not to chance it. Most children's modeling clay is non-sulfur and it's really cheap. I don't know about ceramic clay tho, I do know that the instructions say that you should use a sealer on anything that's absorbent or porous, which ceramic clay falls into that category.

 

batchix:
huh. I wonder which company's silicone sand3 uses, then. Alumilite? :O
(And judging from Smoothon's price, I *thought* they're tin-cure...)

 

Just buy some cheapo rainbow molding clay. (Walmart had it in the back to school section by the crayons. XD)

Remember to clean up the piece with some rubbing alcohol after putting the clay around em.

It's worth it for a few bucks.

 

The Oomoo is tin-cure, but they still don't recommend using sulfur clay or latex products. The silicone is so expensive, I'd rather just get cheap play clay to use than chance it, it's softer anyway. :3

 

Silicone, unlike the resin, doesn't mind water, and when ceramic clay is wet and workable, it's not all that porous unless your using something water-based, which silicone is not. I have used Alumilite so far, yes, it's the easiest for me to get my hands on but I'm probably going to try a different brand for my next project to get an idea of the differences.

 

platinum cure is generally silicone, not polyurethane. Also known as addition cured silicone, as opposed to condensation (tin) cured.

Latex will inhibit the curing of silicone, I've even noticed that where silicone has spilled over rubber bands when I've poured my moulds has remained tacky.

As for what clay is good to use, I just use plasticine which is sulphur free.

Regular pottery clay is also fine, but plasticine is easier to work with. Some people use a clay called Klean Klay, which is made for this type of task. Any outlet that sells resin and silicone is likely also selling the right type of clay to use.

 

woops. Major mistake on my part >_<

 

Not all plasticine is sulfur-free. Roma, for instance, contains sulfur... which is too bad, because I have a ton of it and was hoping to use it to sculpt a doll head out of. T__T

Any ideas on which clay is best to use for the actual sculpt, as opposed to building up a mold?