The basic chemical principle is that oxygen greatly slows the rate that
polyester resin cures or "polymerizes" (the molecules link up in long
tangled strings).

The styrene in the resin will dissolve the wax off the paper. As the resin
polymerizes it squeezes the wax back out to the surface forming a thin
film. This film of wax prevents oxygen from reaching the surface so it
cures completely and becomes almost chemically inert. If it is the last
coat that is what you want it do. You can even buy "sanding aids" that are
a solution of wax in styrene to add to the pot while mixing to promote a
hard finish.

However, if you are laying another coat you don't want that. The next coat
will only be mechanically bonded because the polymer strings can't link up
to the strings in the first coat. As polyester is not a very good adhesive
mechanical bonds are not very strong.

OTOH,as long as the resin is exposed to oxygen the molecules at the surface
don't complete the link up so it does not cure completely and remains
chemically active. The next layer of resin will then be able to chemically
link up to the first layer making the whole lay-up a monolithic mass. It
will eventually cure without wax but as long as the next coat goes on within
a few days it will form the chemical bond.

In other words, if you are working with the last coat polyester can (and
should) be exposed to wax. If another coat of polyester will be laid on
top, avoid wax.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
oups.com...
So I don't know who to listen to. Will wax paper leave me with a
unsuitably sticky surface when cured?
Wax paper would be easier for me to work with than saran.