Which Resin?
 

I have two fiberglass/resin projects for which I'd like to have some
material recommendations:

1) A 1980s semitransparent fiberglass hatch whose top side is
worn/weathered, so that it is rough and fibers are sticking out. I
would like to coat the surface with something that will give an even
surface, cover the itchy fibers, and maybe even bring some of the
transparency back to the now 'frosted' hatch.

2) The top of the companionway hatch has a thin wood layer, wider
stripes of teak with thin stripes of lighter wood in between. These
woods apparently have different heat expansion, varnish will last a few
weeks before it splits at the seams, i.e. everywhere.
I had planned to put some resin on top of that wood, hoping that it
would be more stable than varnish. Maybe a thin glass fiber layer also.
Is the glass fiber necessary?

Which resin(s) would be best for these applications? Both are on deck
in bright sun, both need to be transparent, and create a smooth
surface.

Thanks!

Which Resin?
 

Get the Gougeon Brothers West System book... Read it... Fix your
projects... And become the harbors expert on repairs...

denny

Which Resin?
 

Certainly get the book Denny is recommending. But with that
recommendation, it is implied that you should go with epoxy. I'm all
for that too.

Yes, you're correct that epoxy would make a much stabler base, but you
would still have to coat it with a lacquer with UV filters in it.
However, that will last longer because it is on top of epoxy, and the
epoxy will last longer underneath it, because of the lacquer.

Without having seen it, I'm not 100 percent sure why you would waant
fibreglass on there - except to give it some strength. If the hatch
doesnt flex in any way, and you think that that is the reason for the
cracking, there is no need to use fibreglass at all. Imean, if it's
just because the different woods expands at different ratios, you
wouldn't need to have fg in there.

On another note, though, you will want to make sure the hatch is dry
(as in preferably down to 13 percent moisture), and you will also want
to cover the back of the hatch with epoxy. Not just one surface.

Basically, I'm not really feeling greeat recommending the mastodont of
west system, but it's everywhere, so you should get their ordinary
resing, preferably with the 207 hardener, but you can do with the
ordinary 205 hardener (cheaper without UV filters), and use a good
varnish with plenty of UV-filters on top of that.

About the fiberglass hatch. You will need to remove all the porous
stuff, all the degraded stuff from it. And if it still has enough
strength, you can do and use the exact same approach as with the other,
but for the extra strength get a thin fg woven rowing190grams/sqm, for
instance, also because in that thickness it will be see through.

After sanding the hatch down, removing the degraded stuff, fill it with
epoxy (it's pretty thin when it's non-filled), make sure it has enough
of it (think of it as "end grain wood), then put anothe layer of epoxy
wherein to lie the cloth, and then when the cloth is on, add more
resin, filling the cloth, removing excess (don't put too much pressure
here, as you _will_ stretch the cloth), and then when that is dry
enough you will be able to see where the roving interweaves. Then after
it has dried enough (not completely), you add the final coat of epoxy
to make it entirely smooth. Put varnish with UV filtersover that too.
I think a mat varnish would be better here.

Which Resin?
 

Would Polyester resin do? Polyester is UV resistant, is it?

Thanks!

Which Resin?
 

Chris wrote:
Would Polyester resin do? Polyester is UV resistant, is it?

Thanks!

It would propably do, but why use something that isn't even close to
being as good as epoxy? It certainly won't be easier to use, all things
equal.

The reason I care about the uv is that I want the result to last as
long as at all possible, ut most things degrade with uv - look at
rubber left in the sun, for one. I would certainly use epoxy instead
polyester.
Without a doubt.

the effort to get a good result is about the same, but polyester isn't
as rigid, as waterproof (epoxy is a sort of plastics), or as strong as
epoxy, although it does degrade less with UV. However, it's not just
UV-protection you want. You want all of the other things as well.

Which Resin?
 

Thanks for the info!

I will go with the polyester then, as the main concern is UV stability.

Second are clearness of the coat/layer and adhesion to wood and the
fiberglass (polyester, I assume) of the hatch. Strength is not an
issue, none of this is structural.

Any concerns with that from anyone? (Double-checking before I putting
sticky non removable stuff on large visible parts of the boat.:)

Thanks!

Which Resin?
 

Your reasoning is backwards. First epoxy will stick to either wood or old
polyester far better than polyester will. Second, West 105 with their 207
clear hardener reinforced with a 2oz scrim will be clear with a slight
varnish tint and third it may not seem "structural" but the teak/holly will
continue to expand and contract with heat. Epoxy with a glass scrim will
hold together but polyester will not. You will be taking 3 steps backwards
if you cover it with polyester. 207 is self leveling and has a UV filter in
it but 2 or 3 coats of UV filtering varnish on top is recommended.

I am not sure what to do about your "simi-transparent" hatch. Nothing is
going to restore it to original. You might try sanding it down to get a
reasonably smooth surface and then flowing on a clear 2 part Aliphatic LPU
such as Progressive Epoxy Polymers. Regular laminating polyester is not all
that UV resistance. Most UV resistance comes from the pigment in the gel
coat.

--
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

"Chris" wrote in message
ps.com...
Thanks for the info!

I will go with the polyester then, as the main concern is UV stability.

Second are clearness of the coat/layer and adhesion to wood and the
fiberglass (polyester, I assume) of the hatch. Strength is not an
issue, none of this is structural.

Any concerns with that from anyone? (Double-checking before I putting
sticky non removable stuff on large visible parts of the boat.:)

Thanks!

Which Resin?
 

"Chris" wrote in message
ps.com...
Thanks for the info!

I will go with the polyester then, as the main concern is UV stability.

Second are clearness of the coat/layer and adhesion to wood and the
fiberglass (polyester, I assume) of the hatch. Strength is not an
issue, none of this is structural.

Any concerns with that from anyone? (Double-checking before I putting
sticky non removable stuff on large visible parts of the boat.:)

Yes: polyester does not stick to wood., it might look like it, but you peel
it off very easy. Polyester also does not stick to cured polyester very
well. Use epoxy. Period.

Meindert

Which Resin?
 

"Glenn Ashmore" wrote in message
news:xOp9g.25595$iF3.10122@dukeread01...
... but the teak/holly will
continue to expand and contract with heat.

Another reason to go with epoxy. Polyester is much less flexible and more
brittle that epoxy. Believe me, the poly will fall of all by itself. Been
there, done that.

Meindert