: Tom,
: Whoops, Roger all points above. The only place I suggest using cab-o-sil in a
: boat is in end pours. Those bubbles get pretty big and in total can cut
: the weight of an end pour. I use cab-o-sil to flatten the crease along the
: keel near the stern some times to make packing a rear hatch easier. I
: don't use it to thicken epoxy. Instead, I use it to lighten pours in
: places I am trying to fill. Additional warning, I am not sure why but it
: is my experience that adding cabosil increases the heat generated in the
: curing. thus I do my end pours with my bow sititng in a bucket of water
: with a hose adding cooling water.

I don't add cabosil to my end pours because I want the goop to flow as easily as possible. Cabosil just gums up the flow without decreasing the density. I find that quartz microspheres (Q-cell) does not thicken the resin much - the spheres flow almost like a liquid themselves. This makes a low-density mix that still flows easily. Phenolic microballoons don't flow as easily, but I'll usually add some for color, so I won't see bright white when I drill for a grab loop.