best material for molding polystyrene

I'm melting Styrofoam w/ acetone and wanting to put the goop in a gear mold; however I'm not sure what material I should be using for the mold.  I was originally going to do it in ABS plastic, but wasn't sure if the polystyrene would glue itself to the mold as the acetone evaporates.  So I was thinking of aluminum or possibly stainless steel.  Your thoughts?

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Orngrimm5 years ago
Boah... No idea really! But thanks for the question since i never tought about using PS-goo as molding-material as itself! Cool idea!
Be sure to make an instructable out of that, mate... :)

My 2 cents:
- Place strips of the mold-plastics on baking-sheets and pour a bit of the goo over it. It the evaporation is finished you can check how well each material stuck to the goo.
Also you may maybe be lucky with a silicone-mold (the ingredients are cheap and for sure simpler to use than stainless steel. Or do you have a mill somewhere?).
Maybe this page helps with some make-shift-Silicone-modeling-thing:
What happens to the volume of the part when the acetone evaporates ?
Hm... It should become less. How much? I dont know...
I dont think the acetone changes the PS into other compounds... So the PS should be still be there. Unchanged.

So it may be considerably since it should be close to the volume of acetone evaporated. But i have no idea how much acetone is needed to liquify lets say 100cm^3 of solid PS.

As a basic baseline i suggest writing down the volume of the acetone you start with and compare it against the volume of the finished goo.
If you end up with double the volume, then you should loose around half of the goo-volume if the acetone evaporates.
If you end up with 10% more goo than acetone (90% Acetone, 10% PS), you should loose around 90% of volume...

However, i am speaking here as a 104% beginner since i never did that and my post here i based on basic knowledge only and also a good bit of my own common sense, which may turn out to be wrong. Completely. :)
Its going to make moulding accurately very tricky.
Yes. I think the trick will be to make a goo as thick as possible (Most PS in the least acetone disolved) to get better results. But the volumetric loss will be there. Always.
better to melt it thermally I think