Casting resin in silicone moulds...advice needed (1 Viewer)

[Mardasson]

I have some silicone moulds that I use to produce scenics item with plaster (visible in the diorama section).
In order to get lighter pieces that could be shipped by mail , I'd like to try casting them in resin.

Some of the questions I have :

• Will the silicone moulds be damaged ? (this not being the desire result)
• What kind of resin should I use ?
• What is the price range ? (scenics are rather large)
• Can it be easiy painted ?
• ...and any other advice you may have

Thanks
Michel

 

[theBaron]

I have some silicone moulds that I use to produce scenics item with plaster (visible in the diorama section).
In order to get lighter pieces that could be shipped by mail , I'd like to try casting them in resin.

Some of the questions I have :

• Will the silicone moulds be damaged ? (this not being the desire result)
• What kind of resin should I use ?
• What is the price range ? (scenics are rather large)
• Can it be easiy painted ?
• ...and any other advice you may have

Thanks
Michel

Hi, Michel, have a look at this link from MicroMark, an American mail-order supplier of hobby tools and materials:

http://www.micromark.com/Casting-and-Molding-Supplies.html

I'm sure, though, that there are suppliers who are more local to you

I haven't yet done any resin casting, but I think that you don't need to use mold release compounds, like we do with metal and silicon molds (ie, talc).

As far as painting goes, you can use the same paints that you use for metal or for plastic, and the same kinds of procedures obtain. Clean the piece first, prime it, then apply the finish coats.

Hope that helps, prost!
Brad

 

[BlakeWR85]

Here are two links for urethane resin plastic, you can see the prices. Each are comparable in quality, one is not really better than the other. Each have videos too if you're interested in how they work, pretty straight forward though, most are a one to one ratio of a 2 part compound. Also, some will cure faster than others, you can decide if you want slow curing or fast curing resin. It won't hurt the silicone molds, usually mold release is not needed since silicone doesn't stick to anything, except other silicone without a mold release.
http://www.alumilite.com/Category.cfm?Category=Casting Resins
http://www.smooth-on.com/Urethane-Plastic-a/c5_1120_1209/index.html?catdepth=1

 

[Martin Tabony]

There are basicaly two kinds of resin. Polyester which is used in the manufacture of glass fibre canoes etc. It is quite cheap takes fillers well, it's idealy suited to large products, unfortunatly it is brittle without a binder and realy smells! Polyurethane resin is getting better all the time. Usually mixed 50/50, there's no smell. The down side is that because it has a 50/50 mix you can't play with the catylist to spead up or slow down the cure. There are aditives to do that though. Be carefull that the mould is 100% dry because moisture will stop it cureing! Something that may interest you for future use, you can also buy poleurethane rubber which is half the cost of silicone. Only use it for plaster though as resin will stick unless you use that much relese agent that you loose detail. Degassing is another problem to deal with, I've got a vacume chamber but I don't know what you can do without one.
I've included a link to Alec Tiranti Ltd. They can give you advice and their catalogue is full of things you didn't know you needed until you saw it!

http://www.tiranti.co.uk/

Martin

 

[Mardasson]

Thanks all for the advices and links.
Looks Like I have a lot of reading

No vacuum chamber on hands but do you think a vibrating table might help?
I recently got one and it's very very effective for casting plaster.

Michel

 

[Martin Tabony]

If the moulds are open one piece moulds with no great undercuts, it should be fine to vibrate them, as long as you do it A.S.A.P. before the resin begins to cure.

Martin

 

[fishead19690]

Cutting an additional air vent or 2 into the mold where the resin has a hard time getting to might also help out also. You should be able to cut into the silicone mold pretty easy to add a vent or 2, just make sure they lead back up to where your pouring from.