How to make a latex positive from a latex mould

[crawjaw]

Hi fellow sculptors. I've ony recently joined this forum and I hate asking a question so early on but:

This might seem like an odd request but I would like to make a latex skin from a latex mould. I've sculpted a full size body out of newplast covered foam, and made a 2 part mould using latex and a plaster mother mould. The copy will be cast with resin/fiberglass, but in hindsight I would also like to make a latex replica of the outer skin, so it could be worn as an outfit.
Unfortuantely I don't have the original newplast sculpt.

So, what is the most straight forward way to make the latex skin?

Many thanks in advance.

[crawjaw]

Is it possible to create a latex impression from a latex mould, without the two sticking together? My original post may have been a bit unclear so I've simplified the question. Hope someone says yes and can tell me what release agent to use!

[Tinkerbell]

Hi, I really dont see how this can be done without first creating your form. The release agent wont allow the inner coat to adhere to the former mold.
Couldnt you cast your sculpture then apply latex to that? or would this be too costly?

[crawjaw]

Thanks for your reply. If I create a resin replica of the original, adding latex is only going to give me the same result as the latex mould as I already have. Latex would be a negative of the resin cast - I need a positive. I would have to make a plaster mould of the resin cast then pour the latex.
I was hoping there was a workaround where I could release fresh latex positive from the already made latex negative. I managed to sperate old and new layers of latex on a small test piece using vaseline but unsure if it would work on a large scale piece. Ho hum back to the drawing board.

[nep75]

The problem you're going to run into - or should I say problems ... Latex will stick to latex is one. The big one though is that the fresh latex won't dry against the latex that is there already unless you do VERY thin layers and blow dry. You could end up with pockets of wet latex and that makes a mess (i've done it before- long story).

I would do a plaster cast off your positive (being aware of undercuts of course) then you could cast the latex into that 'stone' mold. That's what plaster molds are called. You can use something much stronger than plaster though like hydrocal or ultracal 30. It would have to be a multi part mold though.

That would be the least expensive way to do it. Or you could cast a PolyUrethane into the latex mold, which would give you a similar result to latex, just won't shrink as much and will cost more. The 74-30 is an amber color and it come in a clear amber.....ooo that would be creepy.

Just some ideas.
Niki

[crawjaw]

Thanks for your suggestions. I think you're right in suggesting making a plaster cast from my positive and taking it from there. I am a complete numpty for not making a plaster mould to start with. That way I could have made a resin replica and a latex skin from the same original. It was just that making the skin was an afterthought and the original got wrecked during the moulding process.
Live and learn as they say. Not sure if I can be bothered now going to all the trouble. Like the idea of the semi-translucent amber though.
Thanks again.

[Daniel]

You could use also use silicone rubber instead of latex or urethane to cast against your latex mold. I've had problems with urethanes before not curing completely or staying sticky on the surface, etc. You can get clear silicone and tint it whatever color you want. Kind of expensive, though.

[crawjaw]

Silicone sounds as though it would work, but as you point out it is expensive. Many thanks for your suggestion.
Apologies for late reply, I've been on hols.:)