View Full Version : Sculpey and Plaster Molds?
April 6th, 2011, 11:48 PM
Hey guys, I'm doing this project out of sculpey and I'm wondering about how effective it is to use with plaster for casting? First time using this kind of clay and my professor's stumped about how it would work in plaster.
I'm not worried about the condition of the original after but I'd like to reuse the clay so I wasn't planning on baking it beforehand. Its the original terracotta type if that matters at all compared to the firm and it'll be done as a 2-part mold.
April 7th, 2011, 07:06 PM
I've never cast sculpey in a plaster mould and would be wary of doing so. A few things could trip you up, the first being that plaster heats up as it sets, which could harden the outter layers of sculpey, locking your sculpture into the mould.
But even if we assume that the plaster doesn't get hot enough to harden the sculpey, how complex is the thing you are moulding? If it is too intricate, with undercuts, bits of sculpey could break off in the detail and be difficult to remove. Also what are you planning to cast the piece in? Latex? If the plasticiser in the sculpey leeches into the plaster it could stop a good thick latex layer from forming.
So while it might work, those are my theories for why it might not. Might be best to make something quick and easy and try it before you risk your sculpture on it.
April 7th, 2011, 07:45 PM
All very good point and warnings. Sounds like an interesting idea though. Fingers crossed 4 u. Please. Let me know how u get on and how u went about it. Good luck.
April 7th, 2011, 09:36 PM
Thanks for the heads up.
I did a small test today with three layers of shellack on the sculpey and it slipped out fine even after forgetting to use vaseline as a release. I did a little googling about it too and one how-to for a head mold mentioned that plaster doesn't stick to sculpey, so hopefully that's true.
I'm making a head about 1/4 scale and that'll be cast in rubber for the purpose of the piece.
April 8th, 2011, 01:12 PM
cool glad its working out.... and luck must have been with u, after forgetting the vasaline... lol i was wundering if i could use wall plaster to make a mold..and maybe use it for casting at some point aswell. as i wont to see how cheap i can do it... we all know how costly it can be to learn from your mistacks and i have know doubt that i will make some... lol its good to make the mistack and learn from the expireance, its being able to afford to test your knowlege again..lol any ideas welcome. lol
April 12th, 2011, 05:34 PM
Thanks for the heads up.
I did a small test today with three layers of shellack on the sculpey and it slipped out fine even after forgetting to use vaseline as a release.
At that point, you aren't going to reuse the clay, so bake it.
At least get the safety of locking in your design in hardened clay.
Why are you using sculpy anyway? For the price of it, you could get a lot more plasticine for your money. Plaster does heat and it might cook the sculpy a bit. OR it might soften it. when sculpy heats, it gets soft before hardening. so don't jiggle it after the plaster starts setting unless you cook it first.
April 19th, 2011, 08:33 PM
I'm also going to make a sculpture with Super sculpey, bake it and then make molds of it like in John Brown's videos, I guess using sillicone like in the video I won't have problems, right?
April 20th, 2011, 04:22 AM
Silicone is preferrable, you just can't beat the result, however the expense of it is discouraging. But for multiple casts you can pull like 100 from one mould, so it can be a good workhorse. It is also unlikely to damage the original. You can also to a degree recylcle the mould when your done with it. Silicone only sticks to silicone, you can bulk up a batch by adding chopped up old silicone.
Plaster is one the cheapest mediums but can be a cruel mistress. However once mastered it's suprisngly versatile. It's been around for decades, with good reason.
Another moulding material is Vinamould or Gelflex. These in essence are rubber than you melt down and pour- once cooled sets to firm but remains flexible. It can be re-used by melting it down again. However setting up this work flow iniatially is pricey and carries it's own hazards and draw backs.
Just my two cents :)
April 20th, 2011, 09:15 AM
Thanks. I was worried because John Brown in his instructional videos said " And here you have super sculpey, great clay if you are not going to make a mold" so I was like... "Whatt???"
April 28th, 2011, 05:42 PM
So it turns out it didn't work so great. The sculpy stuck to the plaster pretty well even after the shellack and mold release so I've been having to scrape it off and losing a lot of detail. I'm pissed I didn't take any photos of the full head beforehand but it was good practice, ended up looking perfect so i know I can do more.
April 30th, 2011, 05:53 PM
im sorry to hear that hun.... still like u said good practice.. learning curve.. hope the next time works out better for ya.