Date: Tue, 24 Jun 2008 21:32:43 -0500
To: puptcrit-AT-puptcrit.org
From: Joe Dunfee <joe-AT-dunfee.com>
Subject: Re: [Puptcrit] Hot Glue Question


 > I'd not considered the Super77, as the planks are 2" thick, and will curve.

Since this type of foam is so much stiffer than the polyurethane 
foams, it fights to straighten out more.  If you are using one of the 
large-bubble versions of the foam (with bubbles around 1/16" or 
larger), edge-to-edge gluing will be a challenge.  Unlike the softer 
foams, the edges of the bubbles are really all you have to glue to, 
since the foam won't let you squish down the bubbles so they 
"deflate" and make more contact.

As someone else mentioned, the cloth strips glued over the seams will 
help a lot. But, depending on the degree of curve, you may not be 
able to get the 2" thick foam to glue edge-to-edge 
successfully.  Thinner foam will curve more.  Perhaps use 1" thick 
foam and then reinforce it on the inside by cutting strips of the 
foam and gluing them inside for a rib structure.

I will also mention that this type of foam is heat formable.  I've 
successfully thermo-formed smaller pieces by heating them in an oven 
before stretching them over a form.  I was using 1/8" thick 
polyethylene, but doubt you could go too much thicker without 
requiring a very long time in the oven, and then a long time to cool 
after shaping it. As you might imagine, this is because the foam 
insulates itself.  Still, even with your 2" foam, if you have it in a 
hot car for several hours before you try to glue it, you might gain a 
little extra flexibility that you wouldn't have otherwise.

Joe Dunfee  joe-AT-dunfee.com
Gordonville, Pennsylvania, U.S.A. 

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