Positive Clay Sculpt to Positive Plaster Mold for Vacuforming

[BrianFinn]

I am new here and would like some advice on making a mold for vacuforming. I have made a vacuum forming table and have a good heat source but am stumped on how to create the mold. I have very hard natural drying clay sculpts but in my research have come across no one recommending to form right over this. I have seen a lot of people use plaster to create their molds. I was wondering if anybody knew any good methods on how to take a clay sculpt, cast it with whatever material and then pour a plaster mixture into that casting. Any advice would be greatly appreciated. I have looked into Silicone 73-20 but that stuff is far out of my price range and I have no familiarity with it. The plaster I have is Plaster of Paris btw.

Any help will be greatly appreciated

 

[Teddz]

You can try using 100% silicon (in a the tube available at a local hardware store), glycerine, acrylic color (to tint it) and try that for your silicon mold. There's some youtube vids that show what exactly you'll need for this process. I personally haven't used this method but, give it a shot as I've seen some decent results with it.

Here's one vid that outlines this process.

 

[BrianFinn]

Thank you

 

[division 6]

Sculpt with WED clay.
Let stiffen till it's leathery.
Vac over it.
Fill with Ultracal 30.
Tune up cast and you're good to go.

 

[TUBBYO12]

I am building a scout trooper costume, and what I have started to do is sculpt the forms using monster clay (http://www.monstermakers.com/product/monster-clay-premium-grade-html) then making a mold using rebound 25 silicone (http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1132/index.html) and using fiberglass for the mother mold, then cast a plaster form and finish it by sanding and sealing it. Hope this helps

 

[division 6]

Plaster breaks down to fast.

You can also make molds out of hard woods, acrylic, high density foam.