One personal observation regarding finishing:
I thought this process was going to be painful, but actually found it to be not
as bad as I thought it would. I honestly did not read the entire procedure
posted
here but I will briefly say what I did.
1.- Clean and carefully scuff sand the fiberglass or gelcoat.
2.- Using the the fishing line technique, apply a nice think coat of expancell
plus West Systems 105. What helped a lot was to use an epoxy pump and a
sensitive
weight scale to exactly measure the ratio of epoxy and expancell. Keeping
the mixture consistent between mixes is key.
3.- Apply the mix using a dry wall spreader modified with an angle epoxied at
the width of the application end. This is also key to keep the spreader from
bending
and creating a concave surface.
4.- Wait until the applied coat starts to gel, remove the fishing line, fill the
groves left by the line.
5.- Using Dura-Block sanding blocks and very coarse sandpaper sand expancell
coat
until no depressions are observed. Most of the time a single pass of expancell
coat was enough. If a few voids are present fix those.
6.- Now the cool part, I used a modified epoxy 2K filling primer made by 5-Star
and rolled it on using a small foam roller. Push hard and fill as many pinholes
as you can.
7.- Once cured, apply coat of Dry Guide Coat (I used Mirka brand).
8.- Sand this coat until all of the guidecoat is gone. Don't worry if this
results
in a good part of the 5-Start 2K to be gone.
9.- Spray one heavy coat of SPI (Southern Polyurethanes) white Epoxy primer.
Welcome
to pinhole land since this primer will make them show like craters in the
moon (it's actually called "cratering" by the people that make the prime which
is very prone to doing this).
9.- Now, without sanding the epoxy primer but before 7 days after applying it,
use thin 3M polyester glaze to fill every pin hole, one by one. This is tedious
but the fantastic quality of the 3M glaze makes the job much easier. The 7
day window is important since the epoxy primer doesn't need to be sanded if the
glaze and subsequent 2K is applied within this time frame.
10.- Sand the pinholes. This part is indeed tedious because the polyester putty
will stick to the sandpaper. The solution was to use a scrap piece of fiberglass
and use it to scrape the glaze of the sandpaper. Use only high quality 3M
sanding paper. The cheaper red one seems to work better though and the glaze
sticks
less.
11.- Spray a heavy coat of SPI grey regular 2K primer.
12.- If any small pinholes show I used red one part lacquer glaze to fill them.
Quicker and easier for just a few of them.
13.- Guide coat, sand until the white shows and almost all grey 2K is gone. the
guide coat will show the low spots. Here you need to gage what fillers to use
to reach perfection. A little more 2K will fill shallow areas but it is a little
heavier. Still I used it. Some polyester 2K glaze is also good. I don't think
I had anything deep enough to go to expancell. If you do you have to do all
the stuff stated above on that area.
14.- Finally, a coat of SPI white epoxy and you can spray the paint (no sanding
needed if within 7 days). Or I flew it on primer for 2 years. The stuff still
looks like the day it was applied and no issues with bugs or deterioration. The
SPI primer is semi gloss so it looks pretty good too.
And I used a forced air respiration system and a dust collector from Harbor
Freight.
I think it is a must.
I can provide more detail on the sandpaper used, 3M glaze PN, 5 Star modified
epoxy
primer, SPI stuff but will have to collect the info. I can also put together
a few pictures.
I hope I didn't bore anyone with this long post.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510542#510542
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