Moldmaking Molds [using plaster instead of silicone?]

If you are planning on casting with resin, then plaster will not work. The moisture in the plaster will react with the resin and cause it to foam horribly. And if you waited for the plaster to become completely dry (a couple months) you would only be able to get one cast done because the mold would break trying to get the piece out.

 

The cheapest alternative is alginate. But you would only get one cast and have to do it quickly because the alginate shrinks.

 

Alginate won't work - alginate is a water-based mold material (think of very unique Jell-o!) The moisture will ruin your resin unless you are using a special resin that doesn't react to moisture.

You might try the paint-on moldmaking latex (you can get it at Michaels or other craft stores) and making a support shell around that with papier-mache....? If you have any latex allergies, though, watch it. It's like death in a jar for me!

 

Casting in resin unfortunately isn't cheap.

To get your expenses down a little, you can use polyurethane rubber rather than silicone... but you will need to get a mold release agent so you can demold. Polyurethane rubber is cheaper, and molds made from it supposedly last a long time. (I've only ever used it to cast wax, but I know it can also be used for resin.)

You could also try the moldmaking latex that I suggested with the paper-mache support shell. The moldmaking latex is brushed on like a skin, and then you would put the papier-mache over it to give it support to keep its shape. I've also heard that you can use silicone bathroom caulk, but only for small pieces it and similarly requires a support shell.

 

Are you making a doll for yourself, or are you hoping to produce them for sale?

If it's for yourself, you can sculpt it in a flesh-tone polymer clay, like Super Sculpey.

If it's for sale, well... there's some variation in prices for different types, but frankly, silicone is expensive. The only real way to make it cheaper is to use less of it. Using a thinner "shell" of silicone surrounded by a plaster "mother mold" is one possibility. You might also consider producing a smaller-scale doll, or producing a head that fits available bodies, instead of a full doll.

I would also caution you against casting a doll for sale unless you're reasonably sure it will sell. I would post it here and see what sort of responses you get. Compliments are nice, but unless you get people asking you if you're going to cast... I wouldn't. There's a difference between a sculpt that people like, and a sculpt that people want to have.

 

Check the stickies at the top of the forum. There are at least two casting tutorials in there -- Donn's and Dolly Daydream's.

Armeleia: I was just browsing through one of the referenced threads, and according to Twigling, latex inhibits resin from curing. Now, I've heard that about silicone, but never resin... still, I thought I'd mention. Not that it sounds like you'd be using it, but in case anyone else is browsing in search of silicone alternatives.

 

I've cast resin in latex molds before I knew I was allergic (yeah, brilliant right?)... and maybe it was just the brand I used, but it did cure with no problems. It was a craft resin, though, so it may be formulated to work with cheaper molds...? Dunno. We're also talking about crappy-quality sculpts, molds, and casts, though... I think I was 15 at the time.

 

Just wanted to say I think I may have been misinformed at that point, but I don't use any latex so I don't know.

You may be able to use hot-melt vinyl for molds, which can be melted down and reused. I have tried some of it but I was not happy with the results. Maybe if you and your friend and cousin could pool resources and you only sculpted the head to cast, then you could mold the head and use the body from another company for your dolls?

You should be able to make a mold for an SD size head with about 1 kg of silicone. And if you only want to make 3 casts, you can get the cheaper tin-cured silicone, or a polyurethane rubber, but since the latter is also resin (that is rubbery) you have to be careful with using a barrier coat/mold release or the cast will stick to the mold.

 

Bargeing in with a question.. I was perusing the Sculpey website yesterday and came across this:
http://www.sculpey.com/Products/products_poly_elasticlay.htm

Is that useable at all?

Also.. I found a similar prodict (at least similar to my untrained eyes)

Alley Goop: http://www.clayalley.com/goop.htm

would this work with resin?

Sorry if it's "stupid questions" I am really just looking for alternatives.

 

Nannii: I haven't used the resin you linked to, but it sounds very much like Smooth-Cast 300 -- polyurethane, low viscosity, fast cure, ivory finish. It looks like it might more expensive, though. Smooth-On is somewhat eccentric in listing their two-gallon kit as a "gallon kit," presumably because each bottle is a gallon. But at the smaller size the price difference isn't that significant, anyway.

FYI, don't buy more resin than you need, and don't buy it before you need it. The stuff has a shelf life, especially once you open it. And be sure to pay attention to safety precautions: Good ventilation and nitrile gloves are the minimum, I'd say. Depending on your paranoia level, you may also want a respirator and goggles.

Armeleia: I know what you mean... my mom has fantastically ugly "art doll" I made when I was, err, somewhat older than 15...

Twigling: I was just looking at the Alumilite FAQ, and they say you can cast its resin into latex... among other things. Including plaster, apparently... go figure. Presumably they mean "completely dry plaster, if what you're casting has no undercuts. " But yeah, Nannii, if you go for any of those alternatives, don't neglect the mold release.

TrekkieGrrrl: Elasticlay (like everything in the Sculpey family) is vinyl. You'd need mold release for sure, and I'm not sure how well it would handle undercuts... it's really not that flexible, or that strong. The Alley Goop silicone putty seems like a better bet -- silicone is what's generally recommended for casting resin. The fact that it's food grade is pretty awesome, too. (Sculpey is definitely not.)

I think my biggest concern with Alley Goop would be distortion. You might need some sort of mother-mold (a hard shell around the silicone). Still, it seems promising!

 

MiraMarie uses a plaster mold and liquiche' technique that look fabulous and it costs alot less, just slightly trickier to make the molds though since you can't have any free edge but she's got a tutorial up
http://www.denofangels.com/forums/showthread.php?t=195987