Expanding foam in a fiberglass mould?

[Wellss01]

I have a fibreglass mold for a head. I want to use this for doing sculpts on. I was wondering if it is possible to take an expanding foam pull out of a fibreglass mold. This mold has no undercuts (already tested). What release would be needed for this to work?


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[fettster]

It is possible but be very careful as expanding foam sticks like a bugger.

You will need to build up a decent wax barrier, best to use a buff in wax as spray was just isn't enough ( I speak from personal experience there;()

 

[piehead]

carnuba car wax works great for releasing, as Rich says though you really need a paste wax you can get into all the surface and then buff until it looks shiney. what i like to do with the first layer is to brush it in and hit it with a heat gun very lightly to melt the wax. i then really get this layer rubbed well in to the mould surface and then buffed. With these foams you are much better using too much release than not enough.

 

[BATS]

the other one I might suggest is Moldlife wax, its basically carnuba suspended in IPA
and because its so thin, it can get into the best places keeping things from sticking

I use it all the time when I run resin in a fiberglass cored mold

But the boys above are both right, when ever you cast hard into hard (hard material into a hard mold) you'll be running a risk of seizure of the mold surface to the material.

Rules of thumb

Hard into Soft = Hard Material into a soft skin mold = resin into silicone

Soft into Hard = Soft Material into a hard skin mold = silicone or urethane into fiberglass, stone or epoxy

those rules followed always minimize the risks

Best of luck!