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I poured my first OOMOO 25 Smooth-on mold today, and I used a technique I saw... somewhere, with a little box made of legos, and the objects pressed into a pad of Sculpey polymer clay.

The mold turned out ok, but the sculpey stuck to both it, and the pieces reeeeeally badly, even with a mold release applied.

A) What sort of clay do you guys use when pouring the first half of your molds?

B) Anyone know what can get sculpey off plastic without ruining it? This stuff is insanely sticky.

I've never seen polymer clay recommended, only modeling clay/plasticine (specifically those brands which do not contain sulfur, which can mess with the curing of silicone). With a proper coat of release agent, sticking doesn't appear to be much of an issue.

Unfortunately, I don't know what could help remove your current mess.

Ah, I had thought that the terms were used interchangeably. /sadface

Some other folks have recommended rubbing alcohol, I'll give it a go and report back this evening. : )

I wouldn't suggest using sculpey for this process. I've seen people pour one half, flip after drying and spray release agent and then pour again but Im not sure if it works with all compounds.


PS HOW AWESOME IS SUPER SCULPEY

Not sure anything will work to clean it off.

Sculpy is not normally sticky, so it seems that you are having an interaction between the Sculpy and possibly the mold release or more likely your silicone. The plasticizers from the silicone may have leached into the Sculpey or they are interacting in some way causing the stickiness.

You may find that the effort to attempt to fix the issue would be better spent on a new mold with modeling clay. Usually these interactions are best cured with time. Set it to the side and leave it for a week or three. The chemicals settle down and have a chance to outgas some.

Nope. Polymer clay is is the stuff you bake to harden; modeling clay is designed to stay malleable (it melts under heat, actually). Too bad it had to be the hard way, but lesson learned...

Is the stickiness a sort of residue or are you just having a hard time getting all of the clay off? I initially assumed the latter case (in which case cooling the piece may help firm the clay up a bit, which could make things easier), but Sean reminded me that the stuff does actually react with some materials. I had a brick that my wife wrapped in cling film, which developed an odd, almost greasy slime on the surface of the clay and softened the plastic. If the clay went funky, my money is on a reaction with the mold release.

Nah, it's just sticky. It's the bottom that is being a real pain in the ass, I used a lego base pad as the bottom of my mold box, and getting it out of all those little pegs is impossible. ~_~


Turns out rubbing alcohol kinda works. It doesnt remove it like a thinner, it just kinda dries it out so it's more crumbly and can be chipped off instead of smearing all over the place. Still decidedly not easy, and very much not recommended.