". . . The home depot wall insulating foam is not dense enough . . ."

Bob Howard

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Not sure if this would be the foam you're referring to, but Ace Hardware sells an aerosol foam product named "Great Stuff"...red or black label...one is stiffer than the other.  If this doesn't sound familiar, you may want to go ask an Ace person.  It's in the Paint department.

http://www.westmarine.com/buy/evercoat--two-part-pour-foam-kit-2-quarts--314080

Two cubic feet might be a bit much though...  1:1 mix means you can split it down.  This type of product is used in certain boat hulls as a structural fill and flotation. 

Phil

Thanks very much, Gentlemen.

I really appreciate the lead on where to get this kind of foam. I hadn't thought of the marine application and I'll check out that DIY foam and I hadn't checked Ace Hardware, Mike.

I appreciate your help!

Bob

Very interesting, Bob. The two part foam I used dried hard but was easy to sand or dremel tool off the excess. But it and the other foams suggested here I don't think are flexible or rubbery. 

Bob, are you recommending a flexible or more rubbery filler for high stress areas like the wing/fuse area I mentioned?

Thanks!
Bob

I can't say that I'm recommending any of these for the purpose you suggested (I've not used the products in aeromodeling) I was just offering a good source of quality alternative foams that might be useful to dampen vibration. Weight and other considerations might be prohibitive but I'll leave that for you to decide. Sorry for any miscommunication /confusion, I wasn't trying to mislead. I do thing a rigid foam would transfer more vibration than say a rubber type foam, but I could be wrong.

Bob

Going totally into useless nit-pick mode (although it may save you some confusion at some point):

Expanded bead foam is the (usually white) stuff that has identifiable beads in it.  They get shipped to the factory as compressed beads (with, I assume, adhesive on the outside), blown into a mold, and then heated.

You're looking for foam, and closed-cell foam* to boot, but not expanded bead.

* Closed-cell foam is foam where the little bubbles haven't popped, so the foam does not absorb water or whatever.  The other kind is like celulose sponges, and I have no clue how you make not-closed-cell foam, or what the proper term is for it (open cell?).

Going totally into useless nit-pick mode (although it may save you some confusion at some point):

Expanded bead foam is the (usually white) stuff that has identifiable beads in it.  They get shipped to the factory as compressed beads (with, I assume, adhesive on the outside), blown into a mold, and then heated.

You're looking for foam, and closed-cell foam* to boot, but not expanded bead.

* Closed-cell foam is foam where the little bubbles haven't popped, so the foam does not absorb water or whatever.  The other kind is like celulose sponges, and I have no clue how you make not-closed-cell foam, or what the proper term is for it (open cell?).

My father-in-law worked at one of those plants for Dart making foam cups, among other things.  They used super-heated steam to expand, transport, and also fuse the styrene pellets.  No adhesives needed.  I'll admit that I don't know a whole lot more about the process.

Some polyurethane foams are closed cell, but not all.  The floatation foam I linked IS a closed cell product.  Evercoat's website is sparse on information, and I have not personally used the product to tell what the general properties are.

Some of the rigid products are open cell foam, others are closed cell foam.  I would look for products that specify the difference, as well as the density and strength.  I have looked at insulation foam and pourable foam before, both for flotation, insulation, and casting, but have not used it.  I am not sure what product to recommend as the details given are frequently sparse.

Phil

Thanks much, Tim. I think I know what to look for.

Bob