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Hi all,

I've been using silicone to make moulds of things I want to cast, but I want to do a one-off cast of a piece of slate that is quite big. So, to save on silicone, can I mould some playdough around it and then pour resin into that mould?

No that stuff gets bloody hot.
you can buy instamold and other casting stuff 2pints for 30$ at michaels tho.

Playdough would probably be fine, although the resin will probably dry it out and may stick to it.

Edit: You may also run into issues with the playdough shrinking as it dries out, which week affect the cast.


If you actually meant plasticine, then no, unless you have a resin that sets at a really low temperature, I would expect the plasticine to either melt or at the very least soften enough to distort the cast.

How big are we talking here?

I know some people use plaster as a mould for large one-off castings so they don't have to fork out huge amounts of money for a silicone mould they are only going to use once.

Not sure how well plaster will hold details and whatnot.

I don't have experience with actual casting of large resin pieces, I imagine there'd have to be resins specifically designed for the task, the resin I use for small scale stuff would be way too hot when casting large stuff.

I used to use play-doh for some small 20mm scale tank turrets for ww2 gaming back in the 80s (had some 2l tins of epoxy araldite A+B) and it sort of worked.

Bear in mind, the turrets were about 1 cubic centimetre in size and were often worked on afterwards to finish them up.

Digging them out often destroyed the mould - which is why we generally would do 10-12 at a time (we had big ww2 games back then).

I am curious how this turns out. I've done lots of small (resin base) castings but I have some big terrain-base ideas that I'd like to cast and have no idea how to get it done...

Please post pics.

OK, some mixed views on this. I guess I could try something very small first, so as not to waste too much resin.

OgreChubbs wrote:
No that stuff gets bloody hot.
you can buy instamold and other casting stuff 2pints for 30$ at michaels tho.

Thanks for the clear statement! I'll be careful. I don't mind ruining playdough, as it's cheap as chips. Your instamold advice is not so useful though, as that works out about the same as buying some silicone, which is what I was trying to avoid.

 corpuschain wrote:
OK, some mixed views on this. I guess I could try something very small first, so as not to waste too much resin.

OgreChubbs wrote:
No that stuff gets bloody hot.
you can buy instamold and other casting stuff 2pints for 30$ at michaels tho.

Thanks for the clear statement! I'll be careful. I don't mind ruining playdough, as it's cheap as chips. Your instamold advice is not so useful though, as that works out about the same as buying some silicone, which is what I was trying to avoid.

In all honesty you may be able to but I am more worried about you getting hurt.
Some of the stuff I use get above boiling temp and I am not sure of the melting temp of play doh. I would be worried of it leaking or melting the play doh. Or it not curing properly ar all.


So if you want to try be careful and know your temps.

OgreChubbs wrote:

 corpuschain wrote:
OK, some mixed views on this. I guess I could try something very small first, so as not to waste too much resin.

OgreChubbs wrote:
No that stuff gets bloody hot.
you can buy instamold and other casting stuff 2pints for 30$ at michaels tho.

Thanks for the clear statement! I'll be careful. I don't mind ruining playdough, as it's cheap as chips. Your instamold advice is not so useful though, as that works out about the same as buying some silicone, which is what I was trying to avoid.

In all honesty you may be able to but I am more worried about you getting hurt.
Some of the stuff I use get above boiling temp and I am not sure of the melting temp of play doh. I would be worried of it leaking or melting the play doh. Or it not curing properly ar all.


So if you want to try be careful and know your temps.

OK, thank you. I will be careful

OgreChubbs wrote:

Some of the stuff I use get above boiling temp and I am not sure of the melting temp of play doh. I would be worried of it leaking or melting the play doh. Or it not curing properly ar all..

Again, playdough won't melt. It's dough. Like uncooked pastry, but less tasty. All it will do under heat is dry out.

You're thinking of plasticine.

I tried it, and it worked just fine!

The playdough dried slightly, but it dries slightly when left out in the open air anyway. The detail was pretty good (it was just a piece of slate, though).
The only issue was that lots of playdough was really stuck to the resin, and I had to give it a good scrub with a brush.

The resin I used was this: http://www.ebay.co.uk/itm/271804303314?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Awesome, got any pics? I want to try this with some terrain bases.

 insaniak wrote:


You're thinking of plasticine.

And when it comes to certain resins, that stuff will prevent proper curing of the resin (ie it won't harden) or will take forever because of the interaction slows the curing time to months.

Iifyou want to retain more detail - and save on the amount of rubber you use you can make a 'glove' mould.

Brush or pour on a small amount of rubber to the item you want to cast. then - when its cured pour over plaster -make a box to hold this in though.

Minimal or no undercuts are the key to this method.

Picture of casting in progress here:

Got a pic of the final product?

I've done tests with wax to see if it would hold up and the doughs detail was impaired heavily but held up structurally. Interesting to see how it turns out

 insaniak wrote:

OgreChubbs wrote:

Some of the stuff I use get above boiling temp and I am not sure of the melting temp of play doh. I would be worried of it leaking or melting the play doh. Or it not curing properly ar all..

Again, playdough won't melt. It's dough. Like uncooked pastry, but less tasty. All it will do under heat is dry out.

You're thinking of plasticine.

I have actually tried casting in plasticine for bases and islands.

It will stick to the resin forever as the heat will melt the oils in it.

Still needa find an alternative and im thinking regular clay as its water soluble.

 Breotan wrote:
Got a pic of the final product?

I tried but can't get a pic that shows the detail. Sorry!

Ink wash it with a water soluble ink for the photos, you will also be able to quality control better.