On Wed, 14 Apr 2004 11:12:18 -0700, BCC vaguely
proposed a theory
.......and in reply I say!:
remove ns from my header address to reply via email

Just a guess from many bitter experiences. What looks "flat" in the
raw will not look flat under a smooth coat of paint. I usually either
work by feel to test flatness, or try to leave a small indentation,
and fill after the first coat as best I can. It may take a couple of
try's if you are really finicky about the result.

A year ago I moved some cockpit winches before painting the cockpit
with LP. Fiberglass boat with 3/4" ply inserts in winch areas. I
drilled out the old bolt holes to new wood and glass, filled them with
West epoxy and their easy sand additive powder - and sanded them flat.

Now they've domed up under the 2 coats of LP and the 2 part primer -
you can see where the bolt holes were/are by the circle of thin bumps.

Any ideas why the epoxy "expanded" up like this. There was lots of
time between the epoxy and the paint - several weeks.

I'm going to do additional work - so would like to rectify these bumps
- probable redrill and refill - but want to eliminate a second batch.

************************************************** **
I went on a guided tour not long ago.The guide got
us lost. He was a non-compass mentor.........sorry
.........no I'm not.

Epoxy and Polyester have different thermal expansion (and cure) rates.
Better to fill the holes with epoxy in the bottom for adhesion (if
needed), and then fill the 'upper' part of the holes with polyester.

Most of the gelcoat repair 'artists' I know NEVER use epoxy for blemish
repair for the above reason. If you keep the repair materials
composition as close to the original base materials, usually the more
mechanically stable outcome will be the result.

Epoxy and Polyester have different thermal expansion (and cure) rates.
Better to fill the holes with epoxy in the bottom for adhesion (if
needed), and then fill the 'upper' part of the holes with polyester.

Most of the gelcoat repair 'artists' I know NEVER use epoxy for blemish
repair for the above reason. If you keep the repair materials
composition as close to the original base materials, usually the more
mechanically stable outcome will be the result.