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Thread: Silicone Seaweed Top

  1. #1

    Silicone Seaweed Top

    Hello all!

    Just going to dive right in. I'm working on a silicone top for mermaid Ulla.



    Materials for casting





    So I just did my test cast today to make little pearls, but the smooth cast didn't cure right. It didn't bubble r anything, but it's still like soft/gummy. Kind of the consistency of rubber when it should be rigid. Any have ideas on what's going on and how to fix it?


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  2. #2
    Senior Member Undisclosed Pod
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    yeah it looks a bit like plasticine!

  3. #3
    Plasticine?


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  4. #4
    Moderator Pod of Cali Mermaid Wesley's Avatar
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    Some thoughts: it cures faster in the heat. I know I told you this already but very exact a:b measurements, is it hard anywhere ? Since it seems like it's gummy everywhere, I think it had to do with mixing or the air. Try a teensie test again and see if it cures this time


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  5. #5
    I poured it in 78 degree weather and post cured it in the oven like it recommended. There's nowhere hard on it


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  6. #6
    Could too much humidity affect it? I might try it indoors tomorrow


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  7. #7
    Moderator Pod of Cali Mermaid Wesley's Avatar
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    Hmmm it could but that would make bubbles I think. Did the stuff in your cup or on your stir stick cure all the way?


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  8. #8
    Nope but those were outside as well.


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  9. #9
    Moderator Pod of Cali Mermaid Wesley's Avatar
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    My money is on slightly wrong measurements.... Or the cup maybe.


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  10. #10
    The cup?


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  11. #11
    Senior Member Undisclosed Pod PearlieMae's Avatar
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    Looks like moisture in your resin. Also, perhaps you didn't have accurate amounts, our maybe didn't mix it completely. The plastic will be flexible at first, but that looks way rubbery. Did you rush the demolding? I know it's hard to be patient. I'd recommend a layer of clay under everything, rather than the foil.

  12. #12
    Come to think of it, I rinsed out the mixing cup before I mixed the resin so there may have been some water left over in the cup. I waited an hour to demold, cure time is 30-40 minutes.


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  13. #13
    Moderator Pod of Cali Mermaid Wesley's Avatar
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    idk i think moisture makes bubbles.

  14. #14




    New test mold. This is before and after 20 minutes. Going to give it an hour today before I pull it but it's already harder than my other mould. This was 1/2 tablespoon of each part


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  15. #15
    Senior Member Undisclosed Pod PearlieMae's Avatar
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    I think you need to mix at least an ounce of resin to get the chemical reaction to fully happen.

  16. #16
    Actually I just demoulded this one and it turned out perfect! I'm not sure if it was the foil or moisture but it worked.


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  17. #17
    Now what to line my mould box with...


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  18. #18

    Silicone Seaweed Top



    Moulds





    Slush casts to clean out clay. I love the way the seaweed looks!!!

    Does curing silicone in too much heat affect it negatively?? I know the hotter it is, the faster it cures but I ha my slush casts under a heat lamp and it took 1.5 hours to reach full cure when it would take 5 at room temperature. Granted these are extremely thin moulds, but I'm wondering if it's bad to cure them that fast?


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  19. #19
    Senior Member Undisclosed Pod PearlieMae's Avatar
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    Probably not...In some Smooth-On how-tos, they advise baking the silicone in an oven to cure it faster and more completely! However, it can 'brown' the silicone. If you're painting it, it's not an issue.

    (re mould box:I line everything with more clay!)

  20. #20
    Haha that's what I did with the mould box. It took forever



    Annddd batch #1 of seaweed


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