Shrink wrap for Mold Release

Discussion in 'Fiberglass and Composite Boat Building' started by LMB, Apr 6, 2011.

  1. LMB
    Joined: Nov 2008
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    LMB Junior Member

    Anybody know if shrink wrap will work for a mold release? I've put together a plywood box to be used as a male mold. Just looking a quick and easy way to seal the surface.
     
  2. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    Do a test with your resin system.
     
  3. Herman
    Joined: Oct 2004
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    Herman Senior Member

    Use packing tape instead, less wrinkling.
     
  4. LMB
    Joined: Nov 2008
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    LMB Junior Member

    Yeah, packing tape was what I started with but since it has no stretch it's difficult in the compound ( or reverse compound) corners.
     
  5. hoytedow
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    hoytedow Wood Butcher

    I had success with saran wrap on a small project using grp many years ago and I believe it is similar plastic. Be careful of folds and overlaps.
     
  6. latman
    Joined: Mar 2010
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    latman Junior Member

    sorry i am late to post but i would brush waxed polyester onto the wood (eg surfboard filler or finish resins), then a coat of mould release wax or PVA and lay up over that surface ,you could also use car bog (bondo) against the plywood and sand that to nice curves before you paint the polyester resin on.

    I think the plastic film may "float " too much ,but the weight of your laminate may hold it down ? and deal with all the wrinkles later.
     
  7. Lurvio
    Joined: Jul 2009
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    Lurvio Mad scientist

    I used packing wrap on my prop blade (4 x 9 cm) mold and it worked, kind of, I was using polyester resin. I would not use that material for anything larger than your palm and not anywhere near a flat surface. Maybe a thicker plastic and tape the corners. Or better yet, try book cover film that has its own adhesive.

    Lurvio
     
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  8. LMB
    Joined: Nov 2008
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    LMB Junior Member

    As a follow-up.. I tried the shrink wrap on a test piece and it did not work very well. The wrap "swelled" as it cured. It may have had to do with the heat lamp I was using to speed the cure but the combination of mild heat and solvents caused some swelling in the plastic. Ended up using packing tape and alot of release in the corners. Faired and refinished after we pulled the part. Turned out nice.
     
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  9. hoytedow
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    hoytedow Wood Butcher

    Good thing. Congratulations.:)
     
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