Is rotocasting the best way to go?

Discussion in 'Replica Props' started by Fetthunter, Jan 30, 2006.

  1. Fetthunter

    Fetthunter Sr Member

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    I have a few parts that are solid, and I'd like to make clear hollow casts of them.

    Would the best way to do this be to make a mold and then rotocast them in a clear resin? Or would it be better to brush on the resin, layer at a time, until it's built-up enough? These are very small parts (maybe 1 cubic inch each, give or take).

    I'm no stranger to molding and casting, but I've never rotocast anything before. Any tips or tutorials out there? I couldn't find anything suitable for my needs after Googling for a guide. :(

    I need to know stuff like how much resin should be in the mold before rotating it, etc.

    Any tips/advice appreciated. :D

  2. Blad

    Blad Sr Member

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    It's very hard - in fact impossible IMHO to rotocast clear polyester resin, as soon as you get to the 'gel' stage the resin will start breaking up, it would also be impossibly boring as you'd have to sit there for 20 mins before you even get to the gel stage.

    You could use gelcoat, but as far as I know you can't get clear gelcoat.

    Polyester resin is not self-supporting unless yu use a thickening material like talc etc - none of which will give you a clear finish.

    You could try to cast the item in a few stages - just put the mould on a flat surface, pour a small amount of resin in and let it cure, then rotate the mould and cast again.

    How about making an inner core in silicone? You may have to make a two part mould with an inner core if there isn't a natural exit point for an inner mould core. You could cast the item in one go then.
  3. StringOnFinger

    StringOnFinger New Member

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    You can get clear gel coat, any boat builder that uses a metal flake in their boat lays down several layers of clear gel coat before applying the metallic to the clear gel coat layer then itÂ’s backed by a solid base color before lay-up. Just FYI :D

    The items are almost too small to rotocast and using clear is tricky to begin with, smooth on makes a crystal clear but to get it to work properly you must cure it in the oven for several hours after curing to get rid of the tacky coat left on the cast. They also make color match which is transparent but not crystal clear, it can be rotocast but you will get small pin holes all over the surface of the part unless you can pressure cast it while roto casting it.
  4. propsculptor

    propsculptor Sr Member RPF PREMIUM MEMBER

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    When I was starting out with plastics I used a lot of Clear Resins from a company called Tap Plastics
    which was local to me when I lived in Northern California.

    There are locations all over but you can order online:


    Click Here for How to do Casting with Casting Polyester Resin.
    Click Here for tips using Clear-Lite Casting Resin.

    They also have Colored tints you can add to the material for different options.

    Back then I used Latex Rubber Molds, heated them with a Hair Dryer or heat lamp,
    then poured in the Clear Resin and I always had great Results.
    By heating the mold before pouring in the resin it gets rid of the stickyness
    some resins get on the surface detail.
    questionstar likes this.
  5. Blad

    Blad Sr Member

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    Thanks for that - that could solve a Predator based problem I've been having.
  6. starbuckcylon

    starbuckcylon Well-Known Member RPF PREMIUM MEMBER

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    Has anyone here made thier own rotocast machine? [​IMG]

    I thought I could maybe rent a Obitron for the weekend if not. :p
  7. Fetthunter

    Fetthunter Sr Member

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    I was going to take a Spin Art machine and attach the bottom of a block of wood to the spindle, then attach my cube-shaped silicone mold to the top of the block and ler her rip, but your idea is more fun. :p

    Thanks for the input guys. I guess that's why Smooth-On sells "trial size" quantities, eh? :lol

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