Re: [MV] Paint Flattening Agent

From: Doc Bryant (rbhonk1@cox.net)
Date: Tue Jun 10 2003 - 23:23:48 PDT


Many paints use talc, the mineral to remove the gloss caused by the resins
and binders. Some of the newer high solids acrylic urethanes and
poly-urethanes have a flattening agent which is some sort of iscocyanate
that reduces the gloss but does not harm the ultra violet and infra red
protecting resins. I would contact Sherwin-Williams Automotive Refinishes
and see if the lab folks will tell you what they are using.

I am familiar with adding silica sand to make an anti slip anti skid
surface, but not as an additive to cut down the gloss of a paint film.
Applying paint in too heavy a coat will cause loss of gloss, otherwise known
as "die back" due to the solvents not being able to leave the applied paint
film. This can easily happen due to the following circumstances:

Improper reduction of the paint with solvent
Use of a solvent that is not adequate for the temperature or humidity levels
encounted when painting
Application of multiple coats of paint before solvent has flashed off
properly (paint coats applied too rapidly)

To effectively make up a gloss reducing agent for paint you would have to
know the chemical composition of the paint, especially the solvents used to
reduce the paint to proper spray viscosity and what resins and binders are
used to mix with the pigments chosen. The newer paint coatings are using
dyes instead of pigments especially to eliminate lead or chromate compounds
which are not too health friendly. I would just bet your paint is pigment
based with a mineral spirit or xylene solvent compound.

Try spraying some metal panels with the paint you are going to use,
experimenting with the solvent to paint ratio.

Start with 1 part solvent to four parts paint and increase the amount of
solvent by 25 percent on each additional test panel. By the time you get to
a 50/50 mix, you might have a paint that will easily run or drip, but also
looses considerable gloss when it dries. The downside to something like
this is a finish that is not very durable. And a finish that can be a real
unpleasant mess to recoat later on if a repair is needed.

Doc Bryant

Doc Bryant



This archive was generated by hypermail 2.1.4 : Sat May 07 2005 - 20:21:43 PDT