REFLECTOR: contamination

[Alan Shaw <wingco@iu.net>]

> Larry ,

Laminate contamination has many sources.  The most common in big shops is
oil from the air compressor and mold release agents.  If there are water
stains on the cloth it most likely won't bond well.  The longer the
project takes the greater the chance of contamination.

Identify and isolate your shops sources of contamination.  Prevention by
leaving peel ply on until JUST BEFORE the next lapup is the best medicine
for kit assembly projects.

Alcohol is a mild epoxy solvent and a good cleaner.  The fast evaporation
requires that you use plenty.  You should still sand and vacuum (don't
blow off with the air/oil hose) JUST BEFORE the layup.

A lot of the above also pertains to painting.  Don't apply and sand your
final primer until JUST BEFORE painting.  Also seriously consider the
porous primers exposure to mechanical sources of oil.  Once the belly
primer gets soaked with hydrolic fluid it takes 6 solvent washings then
three spray and sands with polyurethane until the fish eye is gone.

I prefer to finish the airframe and put on one (thin IMRON) coat of
polyurethane before outfitting and test flying.  It's prevention like the
peel ply.

Alan Shaw