Whoever it was that said "colloidal thickener" fails to make epoxy
nonsagging, and is "very expensive" is dead wrong on both counts. First,
colloidal silica (amorphous silicon dioxide) is the standard filler that you
add to nonthixotropic fillers to make them nonsagging/thixotropic, and it is
nonsagging when used all by itself. Mix it thick and stick it where you
want ...unless it was put on so heavy that you are having high exotherm
problems, it will not sag. As far as price goes, it's middle of the pack.
Consider that wood flour, known as 'cheap', costs 75% as much as the glass
fillers (milled glass fiber, chopped glass strand, and silica). If you want
expensive, go buy straight phenolic microballoons. It costs 150% as much as
silica "colloidal thickener". If you want cheap, go buy plastic minifibers
and accept the trade-offs (which I don't recommend ...there are very few
things I'd recommend plastic fillers for.)

Brian


--
http://www.advantagecomposites.com/tongass -- My 22' Tolman Skiff project
http://www.advantagecomposites.com/catalog -- Discounted System Three
Resins products


..
"Glenn Ashmore" wrote in message
news:Csqmc.7893$Lm3.270@lakeread04...


Parallax wrote:

My epoxy is 10 yr old West System stuff and my metering pumps broke
yrs ago so my mixing is prob a little off. I am using the colloidal
silica I used yrs ago for blister repair and it seemed to work then
but I may not be using the righ amount. Today, I plan to buy another
gallon of the West epoxy, pumps and fibers.

Milled fiber does not thicken epoxy very well. While it is great for
strong bonding it will definitely not make epoxy stiff enough to keep it
from sagging. For fairing and filling I mix in microballoons first then
slowly add silica to get the right consistancy.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com