Postcure Baking of Thin Walled Molds

[SG Merc]

Since I started using Mold Max 40 from Smooth-On, I have only made block molds which have not needed mother molds. My question is that if I were to make a skin type mold using this fairly stiff rubber, would I have to do anything different in the post-cure baking? I am concerned that the thin molds will warp or distort without having something inside or around the mold to help keep it's shape.

Is this likely to be a problem, or am I just being paranoid?

By the way, the molds will be small (no larger than a finger), and I plan to use a plaster shell when casting.

 

[Rhett J Martin]

You should be fine. Just keep you eye on the mold while baking, and take into context that the thinner it is, the less amount of time it will need to be baked. It'll feel odd, and will go against your artistic intuition when you take it out of the oven so quickly, but you'll be fine. Also, watch out for those fumes they throw off, they're nasty.

 

[LordVdr]

Please forgive my ignorance, but this is the first I've heard of baking a mold. Is that a regular step one should take when making silicone molds of something? I've made a couple of molds out of GI-1000, but I've never baked them.

 

[SG Merc]

You should be fine. Just keep you eye on the mold while baking, and take into context that the thinner it is, the less amount of time it will need to be baked. It'll feel odd, and will go against your artistic intuition when you take it out of the oven so quickly, but you'll be fine. Also, watch out for those fumes they throw off, they're nasty.

Hey thanks man! Sounds like really logical advice, so I'll go ahead with the bake once the molds are done, and just watch them closely.

LordVdr,

Baking molds (and also castings) can give the material more strength (longer life for molds, and stronger resin for castings). It's not always necessary, but with certain tin based silicones it helps to evaporate water or alcohol residue which will otherwise hinder resins from curing.

 

[LordVdr]

Dude, thanks for the info. I'll start doing that to my molds from here on out. How long should I bake them, and at what temperature? BTW, sorry if I hijacked your thread.

Hey thanks man! Sounds like really logical advice, so I'll go ahead with the bake once the molds are done, and just watch them closely.

LordVdr,

Baking molds (and also castings) can give the material more strength (longer life for molds, and stronger resin for castings). It's not always necessary, but with certain tin based silicones it helps to evaporate water or alcohol residue which will otherwise hinder resins from curing.

 

[SG Merc]

Dude, thanks for the info. I'll start doing that to my molds from here on out. How long should I bake them, and at what temperature? BTW, sorry if I hijacked your thread.

Those details really depend on the material that you're using. Check with the manufacturer of your silicone. They should be able to provide you with a technical bulletin that includes that information, or at least answer it over the phone/email.

With the material I use from Smooth-On I have to give it about 8 hours at 115F (which is about as hot as I can get with a heat lamp and fairly inefficient hot box).