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mold temperature

Discussion in 'Molding and Casting' started by JEJ, Feb 3, 2014.

  1. JEJ

    JEJ Active Member

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    Has anyone had success/failure with molding a palate with lip line by after pouring the mold putting it back in the freezer as to not allow the frozen part to thaw while mold is curing. Would guess it would need to stay in there for 4-6 days? Any thoughts would be greatly appreciated.
    Thanks.
     
  2. Ok let me make sure I understand. UP pulled a mold with silicone and the mold is still on the mouth, which is in the freezer?

    If you did the mixture correctly it should setup fine. and your casting from the mold should work fine.
     

  3. Should work. It will all depend on what you used for the mold. I don't think it will take 4-6 days to set. I have played around with making molds of ice cubes in the freezer. The silicone set up fine. The ice melted too fast.


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  4. JEJ

    JEJ Active Member

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    Yeah, the palate and lips are frozen in the position I want them but if I poured a silicone mold on them and left at room temp they would start to thaw and lose the desired shape prior to the mold setting up, make sense? Figured if I poured the mold onto the frozen part and then placed it back into the freezer the part wouldn't begin to thaw and distort. I just wanted to make sure if I did this the silicone would still set up. Figured the cold temp might delay the set time (pot life and cure time) just not by how much so figured just leave it in there for a few days
     
  5. antlerman

    antlerman NTA Life Member #0118

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    all depends on the silicone you use. I've only done it with GI-1100 and the cure time was very slow. I think a lot of guys use mold maker silicone from Smooth on. I would ask Doug about that. I think it sets up in the freezer better/faster than most other silicones
     
  6. 3bears

    3bears Well-Known Member

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    For what it is worth, I use 100% silicone out of tube to make a mold of fish and bird heads. I freeze them in the position I want them in, pull out of freezer, spread silicone, I use xylol and a brush to spread evenly. Put it back in freezer, pull out of freezer next day and repeat til I get a sufficient thickness. Make first coat thin and even to pick up detail, the subsequent coats I am not picky. If it is a bigger specimen I then make a support mold out of bondo or something of that nature. This may or may not work for your needs but so far it has mine.
     
  7. use a tin cure silicone
     
  8. JEJ

    JEJ Active Member

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    Yep, using Mold Max from Smooth on. Thanks.
     
  9. idbatman

    idbatman Active Member

    Add Fast Cat and Thivex for your 2nd and 3rd coat
     
  10. JEJ

    JEJ Active Member

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    its wont be put on as coats, it will be a poured mold
     
  11. Your on the right track with the mold max. Watch out for the fastcat. The end result is a faster cure but also a much reduced tear strength and reduced shelf life. If your pouring a block mold just use the material strait, no fastcat and no filler/thivex.

    Another note as I am thinking. You could still experience some melting as the rubber conducts heat/cold from the model.


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  12. 3bears

    3bears Well-Known Member

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    I have to ask, When you mix a catalyst with anything, does it not produce heat? Is that not how it cures, through chemical reaction? In my earlier post the silicone does cure in the freezer. I believe that to happen by evaporation, does that produce heat? I don't think so, if it does, it has to be considerably less than a chemical reaction.
     
  13. idbatman

    idbatman Active Member

    Thanks Doug

    Your right , I don't use Fast Cat in a block mold, I am using it it as a paint on for a slip cast , bird feet. It does seem to be a little stiffer. I end up cutting most of the molds off due to the shape and have to pin them back together . A light coat over the seam seals the deal to get the cast. It has a short lifespan . If you can think of a better way I would like to hear it , I'm open to any ideas to make it simper and easier. I don't mean to rob to the post I just thought we were doing a similar process. I tried a block mold ( like I do a head, PVC pipe) it didn't work.

    3bears I have never noticed any heat from this product.
     
  14. Yes heat is generated but it seams to be minimal. As far as the cure for tube silicon, that is a moisture cure not evaporation. That's why you put a water based paint in it to kick the cure. You could just use water if you wanted to.


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  15. Jay. Your making a brush on out of a pourable. I get that. I could think of a couple of better materials than mold max. Rebound 25 or 40 comes to mind. That material is brushable for the first coats and then a very small amount of thivex will make it thicken right up to build wall thickness. You could do two strait coats in a couple of hours and then a thick coat at the end of the day. It's tough stuff that you may be able to glove off.

    Then you could also look at Moldstar 16. It has a very short pot life of 3 minutes sets in 15 for demold. It's a thin viscosity but if you work it right you can build thickness fast. I used to do a seminar and mold a fish, 4 coats of rubber and the support shell in less that two hours. Fun stuff to use.


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  16. 3bears

    3bears Well-Known Member

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    Thank you Doug and Jay for replying. Doug I would like to pic your brain more about silicone, if you will indulge me? How does silicone cure out in the freezer if it is cured by adding moisture? Would the water not freeze prior to the silicone curing? I have used my share of silicone from a tube in the construction field but have only just begun to dabble in other forms of silicone.
     
  17. I think that the amount of water that you are adding is so small that the silicone is what would have to freeze I order to freeze the water. It normally cures from the moisture in the air. So it cures from the outside in. When you mix water in it cures throughout.


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