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Author Topic: help on plaster mould  (Read 1149 times)

colin-stevens

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help on plaster mould
« on: October 01, 2007, 12:35:00 PM »

once i have vaselined the plug, poured in the plaster, how do i get the residue vaseline of the plaster ready for a coat of PVA?
and what PVA is best to use?
cheers
colin
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RipSlider

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Re: help on plaster mould
« Reply #1 on: October 01, 2007, 02:23:13 PM »

Vodka.

Or any alcohol like substance. I suspect that Isoproenol, available at most model shops will be cheaper though.

Avoid anything water based, and once you've cleaned the positive mould, give it a good long time to dry before you PVA it. ( I use cling film instead of vasaline, but not great for complex shapes.)

Steve
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kayem

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Re: help on plaster mould
« Reply #2 on: October 01, 2007, 02:48:14 PM »

Not too sure exactly what's being discussed here, and I don't know what has been said earlier on this subject, but the only way of sealing plaster moulds I've ever used is to apply either good old fashioned shellac to 100% dry plaster, or if you prefer something a bit more 21st century, cellulose acetate solution. I'd never risk the vaseline method, though I'm not saying it wouldn't work, but it sounds rather risky to me for all kinds of reasons. Shellac or cellulose acetate both work well as long as you don't miss any nooks & crannies, and after the coating has dried, you just apply release wax in the usual way.
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colin-stevens

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Re: help on plaster mould
« Reply #3 on: October 01, 2007, 07:55:33 PM »

Steve, my kind of bloke.
Drink the run off. Vaseline flavoured vodka. what would it be called.
Seriosly, vaseline was sugested by the folks that suppiled the Resin/Ect.
Cheers guys
colin

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Subculture

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Re: help on plaster mould
« Reply #4 on: October 01, 2007, 09:35:22 PM »

With my plaster moulds, I've just cleaned them with a solvent i.e. cellulose thinners or acetone, then varnished them (Ronseal works for me).

Then wax and PVA like any other mould and lay up. I find a conventional cast with gelcoat and resin gives a better finish than plaster moulds. But the latter are much quicker and easier, which is valuable if it's just a one-off.

Andy

colin-stevens

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Re: help on plaster mould
« Reply #5 on: October 01, 2007, 09:41:19 PM »

thanks. alll new territory to me. nice to have thoughts  confirmed
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