Making a mold out of Clay?

Discussion in 'Fiberglass and Composite Boat Building' started by Jeremy Clarkson, Aug 17, 2011.

  1. Jeremy Clarkson
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    Jeremy Clarkson Junior Member

    Instead of building a wooden mold, what If you just dug up a lot of clay and made a long compact pile. Then shaped the hull.
    Then you could wet some fiberglass and lay it on there and when it cures dig the clay out of it and you could use this as a mold or a straight up hull.

    It would be cheap and easy I think

    is it possible
     
  2. wet feet
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    wet feet Senior Member

    Possible-yes.Cheap-yes.Easy-no.Additionally,unless you are a really talented clay modeller,the result will look awful.
     
  3. Stumble
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    Stumble Senior Member

    It is easy, but not particularly cheap if you are buying the clay I would think. A few months ago someone posted on here talking about people using beach sand.

    Anything can be used as a mold, but the question to me is what advantage would it have over traditional methods. In this case, since clay isn't very strong, you would have to have a mass of it large enough to shape a full sized boat out of... Maybe 10' high by whatever length. This has got to be heavy, so finding a place to lay it out would require ensuring the substructure can support it... All to save a few bucks in wood, seems like more trouble than it's worth to me.
     
  4. thedutchtouch
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    thedutchtouch Junior Member

    look into what people are doing for kevlar canoes- basically you build a mold using ply stations, then foam slats/strips (the pink or blue construction foam sold in big box stores), built like a strip canoe though doesnt have to look as pretty. then cover that with drywall mud and sand smooth. finally wrap it in shrinkable plastic ie window covering or boat wrap, and you ahve a mold that if treated nicely will last quite a few canoes.

    edit: this is a MALE mold not a female mold, and typically the bow and stern are left split while on the mold, the canoe is removed and another strip of kevlar is used to join them (to make removal from the mold easier). it can also be done while on depending on the shape of the canoe.

    a kayak could be done by making a top and bottom and having a seam around the edge
     
    Last edited: Aug 20, 2011
  5. gonzo
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    gonzo Senior Member

    The water in the clay will make a gooey mess out of the resin.
     
  6. Herman
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    Herman Senior Member

    and when clay dries, it shrinks. If the lump is too thick, it will crack (my mother was a ceramiste before she got alzheimer). I remember always messing with water and covering in plastic to prevent dehydration of the clay.
     
  7. Jeremy Clarkson
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    Jeremy Clarkson Junior Member

    I'm talking about for maybe a kayak not a ship, you could just pile up the clay on some plywood and when it shrinks 8% thats alright.

    Put some plastic wrap on there and that'd be good I think
     
  8. peter radclyffe
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    peter radclyffe Senior Member

    good idea,what you need is that wax that covers edam cheese
     
  9. Jeremy Clarkson
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    Jeremy Clarkson Junior Member

    Wax is so expensive
     
  10. m3mm0s rib
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    m3mm0s rib Senior Member

    Look at this http://www.youtube.com/watch?v=5kwlNk7-iSg
     
  11. CDK
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    CDK retired engineer

    Car makers all over the world use clay for their prototypes. With the proper reinforcement it is the ideal product for it because it can be shaped and smoothly finished with nothing but a sponge and a bucket of water. They even spray paint it and present the prototypes on international exhibitions.

    Btw, the stuff on Edam cheese isn't wax but "edible" plastic.
     
  12. Steve W
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    Steve W Senior Member

    Im guessing that the clay used by modelmakers is the stuff we all use for temporary repairs,fillets etc in real molds, its not water based so probably doesnt shrink much but it would not be cheap or easy for even a kayak mold.
    Steve.
     
  13. gonzo
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    gonzo Senior Member

    The car model makers usually make metal molds out of clay. Besides, making a male mold for fiberglass is a difficult way to work. It ends up with a heavier laminate too. Non-withstanding the claims of innovators, the old round design for wheels works best.
     
  14. thedutchtouch
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    thedutchtouch Junior Member

    please see post #4 for the easiest, and cheapest mold you can make. it will make up to a dozen or more kayaks if you're careful, and is relatively easy to build and repair if needed.

    furthermore, there's a kevlar canoe yahoo group that details the construction well.
     

  15. gonzo
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    gonzo Senior Member

    I like that. You could make a female mold with that method too.
     
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