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  1. tubachris85x's Avatar
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    Feb 3, 2008, 3:58 PM - Molding/fiberglass casting question.. #1

    Ive been wondering for awhile how to cast a 2-part mold in fiberglass. I mean, I understand how to do everything BUT combining the two halves to make one solid piece. Ive seen I think FP's mold for one of his helmets, it was a 2 part silicone mold with fiberglass jacket, and Im just a little confuesd as to how to cast it so that there is no seam line, or am I just missing something obvious? Thanks

    -Bóđvarr the Tone Deaf
  2. tubachris85x's Avatar
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    Feb 3, 2008, 3:59 PM - Re: Molding/fiberglass casting question.. #2

    Bah, wrong forum..
  3. TD-1536's Avatar
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    Feb 4, 2008, 1:20 PM - Re: Molding/fiberglass casting question.. #3

    All depends on the shape. Something like a Fett helmet could be a single silicone glove and there would be no seem line. The fiberglass mother-mold (aka Jacket) would just be to give the silicone mold rigidity.

    Here's some recent silicone, plaster and fiberglass molds I recently did. Cover your sculpt in silicone, I used Rebound 25, then I covered it with numerous layers of plaster bandages. I could've stopped there, reason being, I used plaster because it's too cold outside to do fiberglass. But, it was a nice weekend outside and I added a layer of fiberglass over the plaster to make them much more durable long-term. Pour in some resin, slush it around, repeat until your desire thickness and BOOM, you got parts.






  4. clonesix's Avatar
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    Feb 4, 2008, 3:54 PM - Re: Molding/fiberglass casting question.. #4

    There will always be a seam line, but it is easily puttied and painted.

    If you were to have no seam, then you would have a "bucket" mold, and you would need to reach your arm into the mold to lay in the fiberglass and resin. Not only would your arm block your view of the inside of the mold, but you would get sticky resin all over your arm.

    Usually, you lay-up fiberglass into each individual half of the mold, Once the resin has gelled to the point that you can trim the edge with a utility knife, you trim right to the edge of the mold (if rubber mold, use caution to not slice rubber) Once trimmed, the two haves of the mold go back together and lay a piece of fiberglass ribbon (with resin) down the seam. When all is cured, a one-piece helmet can be extracted from the mold.

    Depending on how well you gel-trimmed the edges, and how good your mold is, it will determine how clean your seam line is.
  5. tubachris85x's Avatar
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    Feb 4, 2008, 6:25 PM - Re: Molding/fiberglass casting question.. #5

    Thanks guys so much for your help! I thought thats how you would do it, but I wasnt sure. Me and a buddy of mine are going to be playing around with casting in carbon fiber, and from what we've read up on how to cast it, its pretty similar to fiberglassing in that its laid almost exactly the same. Thanks again

    -tubachris

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