From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [FlyRotary] Re: pour foam
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Thu, 15 Jan 2004 13:29:02 -0500
Message-ID: <web-2933714@logan.com>
In-Reply-To: <list-2933663@logan.com>
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>>>	I'm pretty certain that not all foams are equal.

I agree 100%.  I've been using this stuff for years and the only time I've 
experienced problems with it was when I didn't mix it properly.  When the 2 
parts are put together you need to stir vigorously (and I mean VIGOROUSLY) for 
the recommended period... the product I use most frequently requires 30 
seconds.  After my first few batches I knew that I could keep mixing for 40 
and still get it out of the container so that's what I did... depending on the 
hardener you choose the expansion will be from 10 to 30 times the volume... 
high density hardener (ie 6#/cf) expands less (smaller bubbles) than low 
density hardener (3#/cf).  I've found that the 4#/cf product is perfect for 
most applications, you get about 20x volume expansion, it sands well and is 
easy to work with.  My only complaint is that the bubbles are a bit large so 
if you're using it for the basis for a layup it holds a bit more micro-slurry 
than does the 6#.  I compensate by making the slurry a little dryer, kind of 
like thinned peanut butter, prior to skinning with glass or carbon fiber. 
 BTW, this is basically the same thing as Great Stuff, except that GS is a 
very low density foam, probably 1.5#/cf and, as such, remains too springy for 
structural applications.  I use a company called Fiberglass Coatings, Inc. in 
St. Petersburg, FL for a source... their price is right.  I'm pretty sure they 
have an 800 number.  Get a catalog.

  <Marv>