--- In STMFC@..., "Schuyler Larrabee"
<schuyler.larrabee@...> wrote:

Denny's question certainly stimulated a good deal of discussion.

Dennis, asserted that Scalecoat I is an enamel. Really? It's

thinner is lacquer thinner, doesn't

that suggest it really is a lacquer? That's always been my

impression, but willing to learn.

But "lacquer thinner" is just a generic name for a blend of toluene,
xylene, and other rather fast evaporating solvents that can be used to
thin a lot of coatings.

My working definitions, which I believe follow paint and coatings
industry conventions, are:

LACQUER A coating comprised of a resin dissolved in a solvent that
forms a solid film as the solvent evaporates. There is no
polymerization involved, so the dried coating can be re-dissolved by
an application of the solvent. Examples are shellac, a natural resin
dissolved in alcohol, and nitrocellulose lacquer, a plastic resin
dissolved in toluene.

ENAMEL A coating comprised of a resin dissolved in a solvent that
hardens through polymerization after the solvent evaporates. Once
cured, the resin film is chemically changed, and will not re-dissolve.
An example of a naturally occurring polymerizing resin is linseed oil,
which has been replaced by many synthetic resin systems.

Heating a lacquer to speed its drying just forces the solvents to
flash off faster, although a side benefit may be lowering the
viscosity of the liquid coating so it flows out better. Heating an
enamel first speeds the evaporation of the solvents, then speeds the
polymerization.

Dennis