Is it ok to use unbaked Sculpey clay as divider when making RTV mold

[airair]

Is it ok to use unbaked Sculpey clay as a divider for a 2 part mold when making a silicone RTV mold of model made from baked fimo classic?

 

[jager1960]

Is it ok to use unbaked Sculpey clay as a divider for a 2 part mold when making a silicone RTV mold of model made from baked fimo classic?

Dunno about that mate, I use Plasticene, cheap as chips!:lol

 

[airair]

which plasticene? let me know. thanks

 

[zorg]

any, don't use sculpey its waaaay too expensive for that.

i use this stuff


Newplast 500g - Plasticine Alternative, Non Hardening Animation / Modelling Clay | eBay

 

[NormanF]

If you need to do something right now I think it would work, but you should probably try a small experiment first. Otherwise, just order or go buy some proper clay.

 

[airair]

thanks guys.

since im making a silicone mold of my baked clay prop. Do i need to spray any mold release or put anything on it before pouring in the silicone mould?

first time im doing this, so just wanna make sure!

 

[NormanF]

thanks guys.

since im making a silicone mold of my baked clay prop. Do i need to spray any mold release or put anything on it before pouring in the silicone mould?

first time im doing this, so just wanna make sure!

You probably do not need to use mold release, but since this is your first time you should use it to make sure you have a good experience.

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[Bondo Fett]

You are going to need to use a sealer first, certainly, and then a release, possibly. Platinum cure silicones (yours might be tin cure, which is likely) are very prone to cure inhibition by sulfur, which may or may not be present in your clay master. I recommend that you do a small test with your materials before you make your mold, it could save you the frustration of trying- vainly- to wash uncured silicone goop off of your model. Krylon Crystal Clear spray is commonly used as a sealer. Make sure you model is well coated and dried thoroughly, meaning days at least. As to release, with silicone it isn't always absolutely necessary, but is good insurance. Many general releases are formulated with silicone, which would actually act to bond the silicone rubber to your model, so check with your supplier to see which release is suitable for the rubber you are using. Mann 200 is safe to use, I believe, but double check that.

 

[airair]

My prop parts which are made in Sculpey and Fimo don't have any sulphur in them. I emailed both companies to make sure. They said none have sulphur so thats a good step i think.

I got the Polycraft RTV General purpose silicone
Polycraft GP-3481-F General Purpose RTV Silicone Mould Making Rubber - mbfg.co.uk

 

[airair]

hi. once ive cured my first half of silicone mold.

do i need to spray mold release to prevent the second silicone half sticking to the cured half?

 

[NormanF]

hi. once ive cured my first half of silicone mold.

do i need to spray mold release to prevent the second silicone half sticking to the cured half?

Yes. Or wax or vaseline.

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[airair]

i saw on one of the brickintheyard videos on youtube that vaseline mixed with some mineral spirits is ok a mold release?

do you think this will be ok? and shall i put it on my part as well, or just around the part onto the cured silicone?

thanks

 

[NormanF]

I just made the second half of a mold on Tuesday and all I used was vaseline. It was a brush on mold and as I started brushing on the first coat I started worrying that the vaseline would come off and the two halves would not actually be two pieces, but it worked. I used a brush to apply the vaseline, not my fingers. You could probaby use automotive wax, but you should do a test to make sure it will not keep the silicone from curing.

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[airair]

great thanks.
yeah, ill try some vaseline with some mineral spirits. i think it should be ok.

ps, how do you normall tell if the first half is fully cured? since this is the first time im doing this.

its been almost 24 hours now, i pressed my finger against the silicone, i can feel that its almost fully hardened but it does have a slight stickyness to it.

should i wait longer before turning it over and beginning the other half of the mold? i think its almost solid now, but not sure whether to wait a tiny bit longer before attempting the other half.

im pretty sure i put in the right amounts of catalyst. it was 10: 1 and i measured it fairly well i think.

normally, does a 24 hour cured silicone model have any stickiness to it from the top? or maybe that means i need to wait slightly longer? my room is not super warm, but it did get slightly warmer during the morning today.

im in the UK, so weather here is crap!
thanks

 

[NormanF]

"Sticky" is a little subjective. I have a not used rubber for much so I will leave this to people with more experience, but that does not sound right to me. Since someone else will ask: what rubber did you use?

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