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RE: Measurement of Viscosity

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>The particular substance that is supposed to have a
>viscosity of "between 250 and 400 cps" is an ULTRA-LOW VISCOSITY
>Polyurethane injection resin.
I couldn't follow you on why the viscosity couldn't be 200 centipoise.
Anyway the ISO practice on defining units would be lost on most plastics
suppliers. The 'ultra-low viscosity' designation probably means ultra low
for a polymer, which would be a lot higher than water or diesel. As I
recollect a few days I spent in a fiberglass plant the polyester resin
has a consistency between paint and warm honey (greater than crude oil
but less than glycerine, I figure) which would put it in the same range
as your resin. You need the stuff to be light enough to saturate glass
mat, but not so light to splatter and run out. If your urethane is the
stuff used to patch concrete, it'd seem that you'd need something fairly
stiff to keep it from simply flowing through the crack.

I did a little sniffing around and kept running into the 'cps' units for
viscosity. I'd be happier if they'd use standard terminology, but
plastics suppliers' are notoriously imprecise about engineering
properties. They like property scales like NG, OK and GOOD more than
actual numbers. My guess is that cps means centipoise. If you're still
not sure I'd call up the nearest university with a materials science
department.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw


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