Is it possible to cast a silicone layer for detail and fill the rest of mold with foam?

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lavalishus

New Member
I’m making a life sized head mold, I’d like to use platinum silicone for the final head, I don’t want to use up all the silicone however, is it possible to coat the first layer with the silicone and once the detail is there to add foam to fill up the remaining head space ? Thank you
 

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zorg

Master Member
RPF PREMIUM MEMBER
do you mean a cast or a mold? a mold is the thing you take casts out of.

is the foam flexible?

how many copies do you want?

platinum silicone is usually very thin so the first layer probably won't be very thick.
 

lavalishus

New Member
Thank you! It’s a mold yes I made a mold of a mask bust I had, I want to make it into silicone but dont want to waist to much silicone.. don’t have the foam yet that’s why I’m wondering.. and one copy would be fine thank you!!
 

JPH

Sr Member
You are soooo much better off using a decent amt of silicone for the mold, then put some little pieces of foam to make the outside of the mold lumpy. Next, use a rigid outer shell to hold the silicone.

I would NOT skimp on the silicone. If it tears, you will spend more time trying to fix it and probably have to start over.

Get a good 1/4 inch of silicone. Brush on the first layer, try to avoid bubbles.
 

lavalishus

New Member
Thank you!! I do mean however to cast it.. meaning if I can cast a layer of silicone and then the rest with foam? So the final head will have the face with silicone but the rest of the head and the back as foam....?
 

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JPH

Sr Member
The foam will not want to meld with the silicone, so the silicone being lumpy on the non-face side --on the side that contacts the foam-- should be lumpy as registration points. That way you can slip off the face part and add it again with a perfect fit.
 

JPH

Sr Member
Id pack with FreForm Air. Not foam, but a sculptable marshmallow-like substance until it hardens. Also very light.
 

JPH

Sr Member
PS - don't " pack" with Freeform air. Press a thin layer to create a sturdy outer shell to the volume where the foam would fill.
 

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swgeek

Sr Member
You should be able to do a layer of silicone and then pour in a rigid foam. Just make sure everything has set before you pull it out of the mold.
As mentioned before I would make sure the silicone is at least a 1/4" thick.
 

lavalishus

New Member
Thank you! I’m doing it all now the only problem I’m coming across is the silicone not being thick enough? Should I wait for a layer to cure before adding another? The liquid drops from the sides of the head forming a puddle of silicone in the bottom of the cast
 

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