What is a proper grit to prepare "A" faced ply (birch if it makes a
difference) for epoxy coating prior to painting.

Ron

(Ron Thornton) wrote in message ...
What is a proper grit to prepare "A" faced ply (birch if it makes a
difference) for epoxy coating prior to painting.

Ron

Sorry I did not read this post and just responded to the end of the
post. I addressed glueing stuff together in another post but I did not
answer your question.
I would probably use something like 150 to prepare for the epoxy. Put
your goo on real thin the first coat, and sand and apply another...
very thin, no fillers, this should give you a nice surface to paint
on. Then wash off the blush (wax), sand with 250 and have at it. Most
paints will go right over most epoxy without primer in my experience
but the blush must be all gone, check with the manufacturers too of
course.
Scotty
I should note that I am not a fan at all of so called "encapsulation"
and have no time to address that here, but I do often use epoxy as a
"sanding sealer" and then primer as described above. This is for me
an economics thing as I get my epoxy pretty cheap, cheaper than paint,
sealer, or varinish. I can also count on a solid cure in a determined
period, something the others can't always offer me.
"Effin'A"

What is a proper grit to prepare "A" faced ply (birch if it makes a
difference) for epoxy coating prior to painting.

You could sand the surface with something im the 180 - 220 range, maybe even
coarser, but if the surface of the wood is natural, clean and smooth, I believe
you will get a good bond between the wood and the epoxy even if you don't sand.

Almost all my experience is with the Gougeon brothers WEST System epoxy
(http://www.westsystem.com/). However, I believe several of the other epoxy
systems are similar. WEST was developed initially for coating wood surfaces..
the WEST stands for something like Wood Epoxy Saturation Technique.

On plywood or wood, I have put two or three coats of WEST epoxy on. You can
either put on the second and third coats once the previous coat is hard enough
not to run, or you can wait until it cures and sand it. This sanding is both
to get a good bond between the epoxy coats and to smooth the surface for the
next coat. I believe the WEST system literature says that if you recoat within
24 hours you do not need to sand the previous coating.

I believe that if you are coating the surface while it is horizontal, you may
be able to get a thicker coat on without it running, and get away with only one
or two coats.

The instructions that come with the paint you are using should tell you how to
prepare the epoxy surface for painting. Normally I would let the epoxy cure,
and perhaps leave it a few days to be certain I have a complete cure, then sand
with something in the 220-400 range to get a nice smooth surface but with some
texture for the paint to stick to.

Some epoxies, under some circumstances, get a coating called amine blush as
they harden. You are supposed to wash and or sand this off before putting any
more epoxy or any paint on the surface.

Good luck,

Alexander Meller

So many ways to do the same thing reinforces my experience that epoxy is
hard to screw up.

Thanks for all he replies.

Regards, Ron

PS to Scotty, I'm only going to epoxy coat the outside and just paint
the inside. I think that will overcome our mutual concern about
encapsulation.

"Alexander A. Meller" wrote:

What is a proper grit to prepare "A" faced ply (birch if it makes a
difference) for epoxy coating prior to painting.


-----

I have often wondered if plywood surfaces aren't contaminated with the glues etc
used to manufacture the plywood. If so, I would assume a solvent wash and or
sanding would remove? Anyone have an idea on this?

Also, how about adding say 10% solvent the the first coat of epoxy (either with or
without the cloth) to aid in penetration of the epoxy into the wood.

Paul Oman
www.epoxyproducts.com/marine.html

"Paul Oman" wrote in message
...
I have often wondered if plywood surfaces aren't contaminated with the
glues etc
used to manufacture the plywood. If so, I would assume a solvent wash and
or
sanding would remove? Anyone have an idea on this?

When building a 10ft lapstrake dinghy, I mostly wiped the surfaces with a
solvent. But many times I didn't, but never experienced any problems.

Also, how about adding say 10% solvent the the first coat of epoxy (either
with or
without the cloth) to aid in penetration of the epoxy into the wood.

Don't. You thin the epoxy, thinner evaporates and leaved thinned porous
epoxy behind. Normally, epoxy penetrates the wood sufficiently, especially
at higher environmental temperatures. If you really want good penetration,
heat the wood first and then, while cooling down, apply the epoxy. It gets
warm and thin and get sucked because the trapped air in the wood contracts.
Do not heat the wood when the epoxy is applied. You'll get a lot of air
bubbles.

Meindert

Ron Thornton wrote:
: What is a proper grit to prepare "A" faced ply (birch if it makes a
: difference) for epoxy coating prior to painting.

: Ron


Be careful regarding your choice of paints; I did the above
with epoxy then interlux bright-side (brite-side ??) IT DID NOT DRY.

Call to interlux tech support said that the epoxy posioned the
interlux drying catalyst. The guy's rec was to scrape it all off;
I didn't and it is now 4 months later dry enough to be useable.
(after all, you don't
need a catalyst for a chme reaction if you are willing to wait!)

Note: I did clean off the amine using h2o, detergent and de-waxer.


--

almus kenter
`` Pluralitas est ponenda sine neccesitate''