Kenneth wrote in message . ..
On Wed, 19 Nov 2003 23:13:39 -0800, "Evan Gatehouse"
wrote:


"Kenneth" wrote in message
.. .

Howdy,

I have a musical instrument case that I made of fiberglass. it was my
first such project, and the results were good.

The surface has some minor imperfections, and I want to paint the
thing with PBU. Some of the problems are small pits, also, in places,
the weave of the glass is slightly visible. I have seen that the
imperfections are emphasized by the paint and so this question:

What is the best way to "fill" these minor imperfections so that I
have a smooth substrate to take the paint?

Thanks for any help,
--
Kenneth

Are you going to beat up the case a bit or treat it carefully? If #1, then
I'd suggest epoxy mixed with microballoons as a fairing compound. Use a
plastic squeegee (available from marine stores, autobody shops) to apply the
stuff.

If you're going to be a bit more careful, 3M makes a nice line of "Marine
Fairing Compound" - it's like an expensive type of Bondo, but it is
compatible with LPU paints. It hardens very quickly so you can do more
fairing in a shorter period of time.

In either case, the procedure is fill pits, scratches, the weave of the
glass, sand, remove dust, repeat. Repeat until you're satisfied with the
finish. A common mistake beginners make is to use too fine a sandpaper to
fair. Use 80 grit on a random orbital sander to sand the filler. Then use
a few layers of high build primer, fill any remaining imperfections, and
sand with 150-220 paper before painting. LPU paint is toxic when spray
painted so always use a positive pressure forced air system if spraying.

Hi Evan,

I thank you for your valuable information, but have a question...

(Well, two, now that I think about it g)

Is there a downside to the more durable epoxy+microbaloons approach?
And, also, the substrate is polyester. Can I use epoxy over that? Or
would I be using my resin with the microbaloons?

Thanks again,

Another thought. Microbaloons have a reddish tint if I remember
correctly. Personally I have never used them. Cabosil or Aerosil are
white and used sparingly, are translucent to clear in the mix. They
are also harder to sand than Microbaloons, but if you are going to
clear coat or varnish the case, they will not effect the color as
much.
Scotty