Castin' Craft resin - Cured but sticky film?

Discussion in 'Replica Props' started by TylerHam, May 21, 2012.

  1. TylerHam

    TylerHam Well-Known Member

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    Hi All-

    Sort of a part 2 to my mold question from a few days ago -

    The mold went perfect!! I poured some resin in (using the table on the bottle )- And it seems to be hardened, but there is a sticky film on the piece -

    Its been cured for 24 hours -

    Is this something I did wrong? Can I wash it off? Should I let it cure longer?? ITs a thick (3/4 inch - 1" piece)

    Thanks!
     
  2. nachtinis

    nachtinis Well-Known Member RPF PREMIUM MEMBER

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    Castin craft resin is VERY unforgiving when you dont get the hardener/resin ratio at the minimum.

    Basically, use more hardener with that stuff.

    I personally learned my lesson after the first can of it and i dont touch the stuff anymore.

    I use smooth cast crystal clear now.
     
  3. robn1

    robn1 Master Member

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    Castin' Craft resin remains sticky on the exposed surface, parts in contact with the mold should be fine. It's mainly used for embedding objects using many layers, and the sticky upper surface facilitates a bond with the next layer. They make a product called surface cure or something like that, apply it to the exposed surface and it makes it cure.
     
  4. robn1

    robn1 Master Member

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    The mixing instructions seem counter-intuitive. Basically a large volume needs very little catalyst, as it heats up enough to cure. A small volume produces less heat, so they recommend more catalyst.
     
  5. TylerHam

    TylerHam Well-Known Member

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    Ya even the stuff inside the mold was tacky so it killed the casting, and there is residue left on the inside of the mold I dont know how to get out...

    Ug...
     
  6. TylerHam

    TylerHam Well-Known Member

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    On this note - Anyone know how to get resin residue out of a mold???
     
  7. robn1

    robn1 Master Member

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    Tough to say then, maybe not enough catalyst as was suggested.

    Try alcohol to clean out the mold, maybe acetone if needed.
     
  8. thd9791

    thd9791 Master Member RPF PREMIUM MEMBER

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    acetone, that's the remedy for children super-gluing their hand to things - if it can eat through superglue, I would think that would suffice :D
     
  9. nachtinis

    nachtinis Well-Known Member RPF PREMIUM MEMBER

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    Yeah the thicker and more monolithic the item is, the more uniform the catalyst ratio is, the thinner the peice or, if it has thin areas, you have to increase the catalyst.

    I hate the stuff personally.
     
  10. TylerHam

    TylerHam Well-Known Member

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    Ya I'll never use it again
     
  11. MrNixon

    MrNixon New Member

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    I've had the same problem a few times. It could have been caused by a number of things: the ratios were a little off when mixing, not mixed thoroughly, or even the temperature in the room you were in. I used to cast in my garage and during the winter time, the resin almost always had problems.

    As far as cleaning it out, I found applying saw dust (or another powdery substance) and rubbing into the sticky resin will get it out best. It comes out in clumps, then you can respray it with release again.
     
  12. nachtinis

    nachtinis Well-Known Member RPF PREMIUM MEMBER

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    Yeah thats a osmiodic response from the dust, talc works well too for larger globs of goo.

    Then for the thin films try the acetone on a rag, be sure to ventilate.

    Test some of the acetone out on a nother part of the mould first
     
  13. madmanmoe64

    madmanmoe64 Well-Known Member

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    I'm assuming that you're referring to a silicone mould?
    If this is the case then it can often be that the mould absorbs a lot of the heat from the curing process and any part of the cast in contact with the mould will not cure properly.

    There a couple of solutions to this, heating the mould to 120F in an oven before pouring the mould will prevent it from leaching heat out of the casting.

    Similarly, after a few hours of curing you can put the mould and casting in the oven for 5 minutes, to initiate the curing of the last bit of resin.

    or as others have mentioned, you can add more catalyst which will create more heat.

    The problem with too much catalyst is that the piece will cure too fast and, depending on your mould will pull away from the surface causing a crinkled texture.
     

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