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Collapsing Polyurethane Foam ?

Discussion in 'Lifesize Mammals' started by Keith, Oct 11, 2007.

  1. Keith

    Keith Well-Known Member

    Some of the pours of foam I make shrink and collapse the next day, especially when mosture comes in contact with it, ie. hides and glue. In the past I only had problems with the pour foam as it got older, sitting in the jugs, but now it doesn't seem to matter.


    I am very carefull about equal volume measurements as the instructions state, should I do weight measurements instead? I will take any suggestions.
     
  2. Rick Carter

    Rick Carter Administrator

    Keith, this happens sometimes when the foam is not mixed thoroughly. Use a high speed drill and mix it for a minimum of 25 seconds. If it is cool or below 55 degrees you can mix it much longer. Try mixing 50% A and B by weight instead of volume. Part A collects moisture with time and too much moisture makes a rubbery texture. Check the mold release you are using to be sure the components are compatible
     

  3. I was having the same problems with the foam core of turkey heads I was casting. Like Rick said, the high speed of a drill for mixing did the trick( knock on wood).

    BTW, Rick, I don't mean to sound corny but it is an honor to post on the same thread.
     
  4. Rick Carter

    Rick Carter Administrator

    I put my britches on one leg at a time. I'm not all that ,or the bag of chips.lol. It's my honor for you to talk to me!
     
  5. catman

    catman Active Member

    1,049
    10
    congrats on your latest cover Rick.
     
  6. michael p.

    michael p. Getting better with age :)

    Thank you!!! I did not know you could measure by weight instead of volume.....you learn something new everyday on here! Thank's Rick
     
  7. Jim B

    Jim B Active Member

    2,118
    4
    Keith,be very careful that the containers you mix in are bone dry.I've seen guys use milk jugs that have been rinsed out and have a small amount of water left in the bottom.That's all it takes to ruin a batch.If you rinse out jugs to use later to mix foam,leave the tops of so they can dry out completely.I am pretty careful to mix equal parts by volume and haven't had a batch shrink in 20 years.I'm not sure what is going wrong with yours but it is usually water contamination or faulty proportions.
     
  8. Keith

    Keith Well-Known Member

    Thanks for the replies. I always use graduated dry measuring cups, but usually hand mix unless I am using large amounts. I will drill mix in the future.