>
>I looked at the pictures. It appears to me that you could eliminate the
>bubbles by applying just a thin layer of epoxy (without microballoons) onto
>the foam first, then lay the cloth over it.
>
>Dave Morris
>
The foam WAS thoroughly covered with epoxy (or so it appeared) before
putting the cloth on. That's why this "problem" threw me for a loop.
Having done subsequent lay-ups with the micro slurry, I wouldn't recommend
just epoxy. Here's my theory ... and this is purely empirical...
When I apply the slurry, the first few passes of the squeegee leave a slurry
coating that looks porous. As further passes are made, the slurry is driven
down into the cell structure of the foam, filling the pours and leaving a
smooth slurried surface - ready for glassing. It seems that the
microbaloons reduce surface tension of the mixture (compared to straight
epoxy), preventing it from simply "bridging" the pours on those first passes
of the squeegee. This allows you to see where it's not truly penetrating
the foam.
On the other hand, when I had used only epoxy to pre-wet the surface, the
stuff may have been sitting on top of the foam but not really wetting the
foam in certain areas - (areas of surface contamination perhaps!?!). The
cloth that was then put on probably soaked up that surface epoxy, leaving a
"dry" spot in the foam underneath.
Joe
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