Ben and others contemplating using latex house paint as a topcoat.
Be very careful thinning these products with a lot of water for spray
application. I don't want to bore everyone with the technology, but this is
how these products work. The base resin, whether it be acrylic or Poly
Vinyl Acetate, is basically composed of very tiny spherical particles of
resin, water, coalescing solvent, emulsifiers and some various other magic
ingredients. As the water and coalescing solvents evaporate, the resin
particles get packed closer and closer. Finally they are packed so tight by
capillary action that the coalescing solvent migrates into the resin
particles and causes the resin to "fuse" into a continuous film. Without
the coalescing solvent or if its in the wrong proportions, the resins do
not coalesce and the coating turns to dust. If too much water is added, it
can severely impact this process as the water interferes with the fusing
process. The problem with doing this on an aircraft coating is you would
have no idea how severely this has affected the paint. It may appear to be
ok, but you find out later that your latex topcoat starts to lose adhesion
to the primer in the slipstream when the plane goes over 60 mph. Just
remember this is not just a cosmetic issue. If the primer or the topcoat
starts to unzip on the wing, especially in the leading edge area, you could
be in for a world of hurt. The airfoil could be affected the same as if it
had a coating of frost on it and stop flying.
This is why the FAA is so adamant about following the STC for coatings
systems. Its not about cosmetics, but flight safety.
Rick Schreiber
Valparaiso, IN
> [Original Message]
> From: Ben Charvet <bcharvet@bellsouth.net>
> To: <pietenpol-list@matronics.com>
> Date: 11/24/2008 9:19:07 PM
> Subject: Re: Spar Varnish, glue alternatives
>
>
> I experimented with Floetrol, windshield washer fluid, and plain old
> water. The floetrol gave the worse results, and I couldn't tell the
> difference between water and washer fluid. I was honestly surprised how
> nice it went on with the HVLP gun. Getting it thin enough must be the
> trick, and I was probably using a little more pressure than I would use
> for an auto paint job, because there was more overspray. One thing I
> did do was spray all the pieces flat so I could put on a good wet coat,
> the water reducer/thinner allowed it to flow out very smooth. The
> Sherwin Williams latex is quite thick, so I am using 2 parts SW to one
> part distilled water.
>
> Ben
> Oscar Zuniga wrote:
<taildrags@hotmail.com>
> >
> >
> > Ben;
> >
> > I'm quite interested in your latex application technique. You say
"thinned". Does that mean you used Floetrol or water? Two completely
different things, as I understand it... water will thin the paint but
Floetrol makes it flow out. Not sure how much of that is product hype and
how much is real. Either way, one or the other is necessary for shooting
latex from a regular gun so I'm curious as to your technique.
> >
> >
>
>
