I want to take a silicone mold and pull a silicone cast from it. Is this possible? I was always under the impression that silicone stuck to itself -- until I used an old cut up mold as filler for a mold (it never cured around the already hard bits of silicone).
Yes, all you need to do is spray some release agent into/onto the silicone, I use spray wax, but you could also paint on a very thin layer of vaseline (heat the container in a tub of water until it liquifies).
Use a proper silicone release spray usually available where you bought your silicone from and made specially for this purpose , you can use vaseline , but use a craft version available at most art & crafts shops that cones a a liquid that you paint or spray into the mold, not the stuff that comes in a pot as a cream . Wthout a release agent silicone will bond together permanently.
Yeh, make sure you don't get confused with silicon spray- which is sometimes used for resin casting. Its needs to be silicone free, or it will act like a spray glue ;-)
Pretty much what everyone else said will work. The best advise though is to check with your supplier and see what they may have, as it is likely to work best with their product, as the person before me stated.
On a side note, it's kinda funny that two threads about pretty much the same thing popped up at the same time. It just makes me curious.....what's everyone molding?Yeah, curiosity killed the cat, but I'm just nosy!
I have had good luck with this product from Micromark.
http://www.micromark.com/RUBBER-TO-R...2-OZ,8156.html
Others here however have far more casting experience than I will ever have.
-John
I use the micromark stuff also, for my 2 part molds.
Works well.
Spray paraffin wax or similar works wonders, much easier then Vaseline or paste release...
Right now I'm using the same Ease Release 200 linked above and it works fine...
Would this work for fiberglass inside fiberglass?
Fiberglass inside fiberglass could be tricky. Just be sure to use a good amount of mold wax and additionally a spray release agent and to coat every spot.
Actually it's very common, one of the most common ways fiberglass parts are made...skynet said:
Some consideration you can have ZERO undercut, if you have undercuts you need multiple piece molds so you can crack it apart... The fiberglass mold should have a 'tooling' gel-coat on the surface polished mirror smooth, the tooling get-coat is very hard and resilient and will last longer...
What you do then is wax on wax off, literally you apply several coats of common Carnauba (or a specialty fiber-glassing wax) to the mold, multiple coats not just one... Once it's really waxed up you spray or brush on a gel-coat on top of the wax and then proceed to layup fiberglass... Let it dry then use a wedge (or wedge/compressed air combo) to separate the two parts...
This video is short and sweet and goes through the process...
http://www.youtube.com/watch?v=nsvgaWHPMF4
I know it's common, but maybe tricky for a beginner. Sometimes there is suction and pieces wont come apart that easy. Also, there is a chance that people aren't aware that it takes time to cleanly apply release agent everywhere.
Yep. I use Mann's Ease release 200. I like to use silicone postives to make negative vacuform masters. Works great.
Scott
I do that all the time. Usually save about 30% on silicone that way. Couple possible reasons it could fail: (1)You might have mixed platinum based silicone with tin-based. They kinda hate each other. (2) Some tin based silicones don't even like each other. For instance, Ditto Clear (Rio Grande) and Burman 1065 fight. The 1065 inhibits Ditto Clear's cure but not the other way around! I can cut up Ditto clear for use in a 1065 mold. (3) Latex gloves. That'll screw with plenty of silicones and make them do funky things.juno said:
Good luck!
Yep, some silicones won't even stick to themselves... Been there and done that as the siicone I primarily use has very little adhesion to itself (it does stick but you can get it apart, at least if you do it within a short time frame), I can do two piece molds without release and with a little force get it apart, but I don't bother as thin coat of release is so much easier...GunsAndGloryFX said:
Other silicones become one with each other...
Getting familiar with your products is a huge advantage in this hobby, lot of variables...
what's the life of a silicone mold when you use it this way with release agents to cast silicone into it. I'm currently sculpting something I intend to cast in a tin silicone (I've never liked latex as a casting medium for 1:1 stuff) I met up with a prosthetic guy in my area who makes fingers and legs and he uses gypsum material and swears it's great for what I want to do. I wish there was a resin molding system that works like stone molds and last for a long time. So how long does the silicone mold last using it this way?
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