On Sun, 7 Dec 2008 05:31:24 -0800 (PST), "
wrote:

On Dec 5, 12:08*am, mm wrote:
For a long time I've wondered how epoxy spray paint works. . . . . .
I thought epoxies were those which mixed two ingredients at the
time of use. *Is that true? *That doesn't
happen in a spray can does it? . . . . .


There are "two-part" epoxy paints and "one-part" epoxy paints. The
one-part usually do not "cure", they dry.

A two-part contains a moderately low molecular weight epoxy resin in
solvent which you mix with an amine, also in a solvent. The epoxy
and the amine react (at the job site) to form a crosslinked film.
Crosslinked films can be made harder and more durable than non-
crosslinked films.

A one-part epoxy is actually a high molecular weight, non-crosslinked
resin manufactured by reacting a low molecular weight epoxy resin with
bisphenol A in a chemical reactor.. The resins may or may not
contain a small proportion of leftover epoxy groups. They may or
may not be used in situations where one "cures" the leftover epoxy
groups.

Once upon a time, when the earth was young and I worked with epoxy
resins, they used high molecular weight "curable" forms in industry,
and non-curable forms (no leftover epoxy groups) for sales to
consumers.

The solid, high molecular weight material is dissolved in a solvent
more or less like a lacquer. If no curing agent is used, the dried
film is not crosslinked, and is not quite as durable as the cross-
linked film resulting from a two-part epoxy. However, all epoxy
based coatings tend to be very durable, a feature which compensates
for their higher cost-of-manufacture.

Regards
-J

Well, no wonder no one else answered this part. Too complicated.

Thanks. I got most of it but I'll read it a second time after I read
me email.