Flexible mold materials safe for silicone?

[Lily]

I screwed up by making a rigid mold of something that, in hindsight, really should have been made with either a flexible material or a multi-part mold.:shame:I'll do my best to salvage it but I might have to redo the sculpt and make another mold. Since I'm not great at multi-part molds, I'm hoping someone here could recommend a flexible material that won't inhibit silicone cure. (I know I could use silicone for this, but I'm terrified of having the cast stick to the mold if something goes wrong with the release agent.)

I swear I saw this mentioned in a tailmaking thread at one point but I can't find it. Is there a type of rubber mold I could use?

[Aysun_the_Mermaid]

Is this the one you meant?

A few posts in Theobromine starts talking about a urethane rubber, I believe...

http://mernetwork.com/index/showthread.php?t=12030

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[Lily]

Thanks for that, Aysun! What's weird is the smooth-on rep I talked to said he didn't recommend urethane rubber for use with silicone due to potential cure inhibition.



My worry is that Platinum-Cure silicone will not cure inside of a urethane rubber mold.

Maybe he meant he wasn't sure... I guess I could always get a sample size and test. Honestly I feel like half of tailmaking is just figuring out what won't make everything explode...

[PearlieMae]

Use a urethane resin, not rubber. Smooth On has some flexible resins...I can't remember the name right now.

Have you looked at their video how to page?

[Theobromine]

I use urethane rubber (not resin) for all my molds and have never had a single cure issue in the year+ I've been doing this. I use TAP Plastics brand. The silicone peels out easily even if I don't use a mold release (though it works even better when I do). And yeah, flexible molds are the best.

[Mermaid Alaria]

I use urethane rubber (not resin) for all my molds and have never had a single cure issue in the year+ I've been doing this. I use TAP Plastics brand. The silicone peels out easily even if I don't use a mold release (though it works even better when I do). And yeah, flexible molds are the best.

This thread is so helpful!
Love your work Theobromine :jawdrop: espcially your new tail. Your sculpting skills are now legendary! Could you tell me what clay you prefer? and as far as TAP products... Is this the urethane rubber (http://www.tapplastics.com/product/mold_making_materials/mold_making_supplies/tap_urethane_rtv_mold_making_system/63) you use exactly? Also, people have talked so much about dragonskin I didn't know there was a viable alternative til now...what's the TAP analog you used? This one (http://www.tapplastics.com/product/mold_making_materials/mold_making_supplies/tap_platinum_silicone/494)?

[HamptonsMermaid]

I'm using urethane rubber from Smooth on (ReoFlex 30). A little tricky to pour since the uncured parts are very toxic but the test molds came out nice. I've only done one test with silicone so far and the surface came out tacky, which Theo said that the first pull is often like that, and that I should let the mold breathe for a few days first. Will do another test once it airs out.

But yes I chose urethane rubber bc I travel a lot and have limited storage, so I don't want something brittle and hard to store or move around.

[Theobromine]

This thread is so helpful!
Love your work Theobromine :jawdrop: espcially your new tail. Your sculpting skills are now legendary! Could you tell me what clay you prefer? and as far as TAP products... Is this the urethane rubber (http://www.tapplastics.com/product/mold_making_materials/mold_making_supplies/tap_urethane_rtv_mold_making_system/63) you use exactly? Also, people have talked so much about dragonskin I didn't know there was a viable alternative til now...what's the TAP analog you used? This one (http://www.tapplastics.com/product/mold_making_materials/mold_making_supplies/tap_platinum_silicone/494)?

Thank you so much! Yep, that's the exact urethane I use for my molds, and the silicone I used as my first tester. I don't actually recommend TAP silicone for a full tail, though, as it's not as strong as Dragonskin (and it's way more expensive in the larger quantities). However, it was great to practice with and the small "test" quantities aren't expensive. I just buy gallons of dragonskin now, though. Much more cost effective if you need a lot, and more durable in the long run.

[Theobromine]

Oh, and um (since I just scrolled up to re-read the previous comments and remind myself what the rest of the discussion here covered) you can use a silicone mold to cast silicone in, as long as you use a release agent. I know it sounds scary, but I've tried it a couple times and it works. Just as long as you've coated the surface in a thin layer of grease (vaseline or spray-on release agent) it won't stick. I mean, if you're painting silicone, you have to make sure you clean the surface really well anyway. Just fyi. I wouldn't generally bother with it, but for example if you want to make a small mold really quickly and not wait a couple days for urethane to cure...you can try it. I did a crash course in silicone prosthetics for a cosplayer friend of mine the other weekend (and also wanted step-by-step photos of the entire process for a panel I gave at comicon) I showed her the process using silicone for the molds as well as the casting. We just quickly sculpted some simple scar appliances so we could do the entire process in one evening. I also have a two-part mold I made with some spare smooth-sil 945 because I just wanted to experiment with the process of two-part moldmaking. Anyhoo. Don't be scared to try it if you need to.

[Mermaid Tami]

I use urethane rubber (not resin) for all my molds and have never had a single cure issue in the year+ I've been doing this. I use TAP Plastics brand. The silicone peels out easily even if I don't use a mold release (though it works even better when I do). And yeah, flexible molds are the best.

Thanks for this information, I'm getting ready to start a top for my first project and I was kind of confused on what kind of mold to use. I've looked through tons of threads before but now that I'm ready to start, I'm having a hard time finding them again!

[xaccer2]

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[xaccer2]

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[xaccer2]

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