Disassembling master sculpt for casting

[fabricious]

Hello there, fellow enthusiasts~

Since I am soon going to work on a new 1:20 dinosaur model (Albertosaurus sarcophagus, if I don't change my mind), I am having a bit of a crisis figuring out how to properly disassemble a master sculpt (made of super sculpey) in order to turn it into a proper resin kit. The first sculpture I molded (my Pachyrhinosaurus) staid in one piece, which resulted in a nightmare of getting it out of the mold + lots of trapped air bubbles and so on. Also, I had to use an enormous amount of silicone for the mold. Can anyone maybe give me some advice on how to tackle that problem? I would even be glad for tips about good books for said topic, since the internet did not really give me a lot of answers.

Thanks in advance!

[Gorgonzola]

Hopefully someone with more experience under their belt can chime in because it's been ages since I had to cut up a sculpey model, but it can be dicey.

If you haven't started it yet, you could build your armature so it can separate out without any trouble (This would involve constructing telescoping limbs out of brass tubing. John Brown has an excellent DVD from Gnomon Workshop that covers this sort of thing.) Build up your model as you need to, then when it comes time to cure the sculpey cut the separating areas with piano wire or similar and clean up the edges. The downside is because sculpey is a fairly soft sculpting material a lot of detail may be marred and require a fair amount of reconstruction around the edges.

The other alternative is to construct and build as normal, then after you cure the sculpey cut it with a jeweler's saw. You may need a dremel tool to cut through the armature wire, but a jeweler's saw should be able to cut through sculpey without too much trouble. Be aware depending on how clean you can perform the cut you'll run into issues of restructuring the edge again.

[brandem]

To maintain your details and make as little work for.the assemblers as possible? Hard cure the clay then make the external cut with a dremel 545 diamond wheel, then make the rest of the cut with a diamond wire hand saw

[fabricious]

Thanks a lot guys! This is already giving me a much better idea of the process. The sculpture is only a wire armature so far, so I could definitely still change it. Maybe there's some other techniques someone might want to share, luckily I can't work on my sculptures right now, so I can still collect some information.

Greetings,
Fabrizio

[Newt]

You could make your rough sculpture in Sculpey as usual, cut it up as mentioned above, then finish each part separately.  If you go ahead and finish and bake the torso first, you can line the other parts up against it to finish them without disturbing the torso detail.

If you want to go another step, after you cut up your rough sculpture, cast each part in wax and finish it.  Then you don't have any wire in the final sections to get in the way of keying- plus wax allows super crisp detail.  This technique is described in the book Pop Sculpture (which I highly recommend, even though it's focused on human sculpture).  I haven't tried this technique yet, but I hope to soon.

[fabricious]

Thanks Newt, that sounds like a great idea! I might try that. I'll definitely keep an eye open for that book!