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How much and what density foam

Discussion in 'Molding and Casting' started by maximum, May 2, 2008.

  1. maximum

    maximum The one that got away! Made the other guy Famous!

    I have been reading on us composites website and I can not decide which foam would be best for a deer form. 2,3, or 4lb? You experienced guys tell me how much foam will it take to pour a form?
  2. George

    George The older I get, the better I was.

    I'm just going to give you a name: McKenzie Foam. Most foam is bought from a taxidermy supplier anyway and those light weight foams just plain suck. They don't sculpt well for alterations simply because they're of a lower density and the tools to sand them tend to eat deeper into the cheap stuff. When I buy foam from a foam producer such as Jameson, I specifically ask for 5-8 pound density. This gives a tighter,more compact foam that will not crater when you touch it.

  3. bill@hogheaven

    [email protected] New Member

    Weigh a similar size form & start with that much foam. You will have to fiddle around to get it perfect & different foams expand differently. Also temperature plays a huge role in expansion rates. Foam should be mixed by weight, not volume.
  4. George

    George The older I get, the better I was.

    Well, I don't "weigh" the foam as for shop usage, I don't see that as a player. In fact, at Joe Coombs, I know that their manikins are poured with foam that's measured in cut open plastic milk jugs by volume. One thing Ken Walker showed me was that mixing it LONGER with an electric drill will get you MUCH more foam than simply stirring or mixing quickly. He completely dismantled that lion in my shop last month and then put it back together totally with foam. We used McKenzie foam and for all that work he used a bit over 1/2 GALLON of foam (1 qt. "A" and 1 qt. of "B"). I'd have used a gallon and a half. He simply stirred it with a bent wire and a drill for a good 30 seconds or more. Then he'd wait until it started to expand. He told me that if he poured it and it dripped out, he'd not mixed it properly. He stated that in Canada, shipping foam is truly expensive and he's just learned what it can do. Next time you mix foam, try stirring it longer and pouring it only fater it starts to expand. You'll be amazed.
  5. bill@hogheaven

    [email protected] New Member

    Mixing longer certainly affects expansion but theres the added problem of getting 4# of the stuff poured before you lose it. Pouring mannikens can be an adventure, as can demolding.
  6. jermh1

    jermh1 Member

    i just stick a plastic spoon in my cordless and go till it gets darker then you have a few seconds to work with it. Im not sure if its the right way but I try to work it around the sides as it starts to expand. also noticed a big difference in how much it expands as opposed to the quick hand mix. for volume I do a trial cast in a few pours then weigh it then get an idea of amount of stuff to use and eye ball it from there.
  7. lorefuma

    lorefuma Member

    I'm sorry... :-[
    I live in Italy, you consider 4-5 lbs for? cubic feet?
  8. kebees4

    kebees4 New Member

    Your mix ratio between your ISO and Poly will also change blow rate and density. Improperly mixed foam will also change it. Improper venting of the molds will also change the density. I work in a factory that pours totes of foam every day and the slightest change can cause problems. Foam should be mixed by weight. If you add more iso it will get firmer and blow more. Every foam has a specified free blow density. If you pack molds more you can raise the density if there isn't to many vents. Hope this helps you out.