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Making a mould from a casting

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  • 02-04-2014 2:29pm
    #1
    chopper6
    Banned (with Prison Access) Posts: 3,214 ✭✭✭


    So i want to do things in reverse order!

    i have a very nice concrete casting of a garden ornament and a couple of people have asked me can i get them one...i feel i might be able to flog a few as well but i'd need to make an actual mould to start turning them out.

    I would be using concrete as a medium and the mould would obviously need to be pretty robust.

    Anybody got any ideas how to proceed?


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    #2
    makeandcreate
    Registered Users Posts: 451 ✭✭makeandcreate


    chopper6 wrote: »
    So i want to do things in reverse order!

    i have a very nice concrete casting of a garden ornament and a couple of people have asked me can i get them one...i feel i might be able to flog a few as well but i'd need to make an actual mould to start turning them out.

    I would be using concrete as a medium and the mould would obviously need to be pretty robust.

    Anybody got any ideas how to proceed?
    I was going to do a course to learn how to do this last year - the guy doing it had a FB page called Acorn Crafts or perhaps Acorn homecrafts if you want to look him up.
    Otherwise there are plenty of you tube vids outlining the process.
    Used Silicone moulds often come up on E-Bay - maybe you'd find your mould on there - it would probably be cheaper to buy a used one than make one.


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    #3
    chopper6
    Banned (with Prison Access) Posts: 3,214 ✭✭✭chopper6


    makeandcreate wrote: »
    I was going to do a course to learn how to do this last year - the guy doing it had a FB page called Acorn Crafts or perhaps Acorn homecrafts if you want to look him up.
    Otherwise there are plenty of you tube vids outlining the process.
    Used Silicone moulds often come up on E-Bay - maybe you'd find your mould on there - it would probably be cheaper to buy a used one than make one.

    Checked ebay...for the size i'm looking for is 250 dollars!


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    #4
    makeandcreate
    Registered Users Posts: 451 ✭✭makeandcreate


    Using urethrane rubber would prob be your best bet. You'll also need releasing agent & maybe a sealer to protect the original piece. Dipping the piece into a big bath of the stuff would be the easiest but coating the item with layers of rubber would probably work out much cheaper.
    Depending on the shape of the item you'll also need a support jacket to stop the wet concrete distorting the shape of the mold. These are often fibre glass.
    * Reusable
    * Molds can be used over and over again.
    * Does not shrink
    * Has good abrasion resistance.
    * Comes in a wide range of hardnesses and therefore gives long mold life.
    * Can be poured, brushed or sprayed on to the original model.
    * Is the most economical overall (compared to other mold rubbers).

    General Overview: To be successful in making a urethane rubber mold suitable for making one or more concrete castings, you need to first prepare your model to release the mold rubber (apply a sealer and release agent). Next, mix and apply mold rubber - if brushing or spraying rubber onto mold, applying a support shell will be necessary once the rubber is cured. After rubber is cured, remove from model. Before casting into mold, apply a release agent to facilitate demolding of cast piece. Mix and cast concrete or other material into mold. Allow concrete to dry and demold. If you have done everything correctly, you will have an exact copy of your original and can making many castings with your rubber mold.

    There was a company in Ireland selling it I think - I know when I wanted alginate gel for a bodycast I did find an Irish supplier of mould making stuff - google should help you out.


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