Re microbaloon costs. I help make one of these products. And no, I can't
get you free samples. But the prices you are quoting are something like
twice the selling price in bulk quantities. I'm talking shipping container
loads of several tonnes. In those quantities it's sold by mass.

If you are getting one pound mass of spheres in your tin at a retail level,
you are getting a very good deal. I'd suspect however you are getting
whatever fits into a "1 pound tin" - whatever that is. So I can't comment
on what additional costs and margins have been added along the distribution
chain, sufficient to say that anyone who has ever handled this sort of
product will recognise that measuring and re-packaging it is not the easiest
exercise.

I'd rather not get into a discussion of the various measurements of density,
suffice to say that what you are really adding to the epoxy is encapsulated
air. The air is added to modify the properties of the epoxy ( lighter,
easier to sand, different viscosity , whatever ), and/or to reduce the cost
for a given volume.

If you are only interested in reducing the volume cost, I'd be surprised if
it's worth adding a hollow sphere product unless you are using some pretty
serious quantities of resin and filler. If it's volume cost you need to
reduce, there are much cheaper fillers than hollow spheres, but they are
heavier. If it's viscosity you need to increase, Glen has pointed to fumed
silica - it's got the surface area.

Since any filler changes the properties of the polymer it's being added to
( not necessarily for the worse) it's like Glen says - you should understand
what the filler does in the resin system you are working with before you
think about the costs.
DF


"Lew Hodgett" wrote in message
nk.net...

"Glenn Ashmore" writes:

Forget it Lew. Until they understand what fumed silica and microballons
do it is no use to argue.

Agreed, but sometimes I get bored.

Lew