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using expanding foam for a mold backing

PostPosted: Wed Apr 22, 2020 7:06 pm
by blackmarketbaits
so I just poured a fairly large mold, 8x8 sq in. roughly. its a injection mold for 5 in. paddletail swimbaits. and I was a little short on the aluminum powder resin to fill above the highest point of the masters. i completely covered the surface of the parts though. I have some Expanding foam resin, the tough stuff, laying around. could i just pour that in to make a backing for the mold halves? the foam and the aluminum powder resin are all urethane based so they would bond together right? or am a wrong in thinking that? i have multiple walleye anglers chomping at the bit to buy these after seeing the results in field testing last spring. if I have to I will wait until i get more of the Aluminum resin. thats alot of money in molds and time in the masters.

Re: using expanding foam for a mold backing

PostPosted: Thu Apr 23, 2020 7:04 am
by dahlberg
I assume you are talking about Alumifoam in regards to the "tough stuff". For sure you can use it, but as you know it will expand about double. If you can deal with the expansion, I see no problem with your plan. I am assuming none of it will be in contact with the actual surface of the mold. If it was me, i would likely try to use a fill material that doesn't expand. RC3, Alumilite white, or even two part epoxy in any permutation from paste, putty, ribbon, or thick glue.
Hope it works out. Those walleyes are snapping right now!
best,
L

Re: using expanding foam for a mold backing

PostPosted: Thu Apr 23, 2020 10:39 am
by blackmarketbaits
thanks for the Info!!