I have a polyester/ glass laminated part (gelcoat on one side) and I
need to repair a hole in it. In the past, Ive sanded the
glass/polyester, cleaned it up with acetone and then used west epoxy and
"boat tape" glass. The polyester part is about 4 years old.

This works reasonably well but the bond doesnt seem as good as the
original polyster glass to glass laminations or if I were bonding epoxy
to epoxy.

Any suggestions on a really strong way to fix holes in polyester
laminated structures or improvements on what Im already doing would be
appreciated.

Regards,

wh

When I patched a 3" thru hull hole on my 3/8" thick HR28 hull,
all polyester glass, I used a 'feathered' polyglass patch and
could not see it after it was done. I cannot imagine the bond
failing, I tried to dig at it with an awl, etc. There is no way
I would not use epoxy to repair polyester, because from then on
you would need to cover it with epoxy. It would complicate even
bottom painting. Grind out all the epoxy, rough sand, clean with
acetone and restore it to like new with like material.

Don't think about it too much. Do it like the pros do. Feather
the edges inside and out, and learn how to mix and glop
polyglass.

If you are worried to the point of doing engineering studies
hypothecated on driving over rocks, you would do better to study
the charts.

Opinions, opinions, ever'body gots opinions.

Terry K

Walt wrote:

I have a polyester/ glass laminated part (gelcoat on one side) and I
need to repair a hole in it. In the past, Ive sanded the
glass/polyester, cleaned it up with acetone and then used west epoxy and
"boat tape" glass. The polyester part is about 4 years old.

This works reasonably well but the bond doesnt seem as good as the
original polyster glass to glass laminations or if I were bonding epoxy
to epoxy.

Any suggestions on a really strong way to fix holes in polyester
laminated structures or improvements on what Im already doing would be
appreciated.

Regards,

wh

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hypothecated on driving over rocks, you would do better to study
the charts.

Well, I did GET the hole by "driving" over a big rock land sailing... I was
hoping the rock might take the damage next time.

Walt ) writes:

hypothecated on driving over rocks, you would do better to study
the charts.

Well, I did GET the hole by "driving" over a big rock land sailing... I was
hoping the rock might take the damage next time.


perhaps if you glass the rock the boat will slide over.

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Best bond is with epoxy, rock or hull.

Ron

Ron Thornton ) writes:
Best bond is with epoxy, rock or hull.

not if "best" is "the lowest cost bond which satisfies the requirement".

to prove the hypotheisis that epoxy is the best resin to glass a rock so a
boat will glide over it you have to perfrom a controlled experiment with
sufficient replications to be statistically significant. my money would be
the polyester as the lowest cost bond which would meet the requirement.



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Walt wrote:

I have a polyester/ glass laminated part (gelcoat on one side) and I
need to repair a hole in it. In the past, Ive sanded the
glass/polyester, cleaned it up with acetone and then used west epoxy and
"boat tape" glass. The polyester part is about 4 years old.

This works reasonably well but the bond doesnt seem as good as the
original polyster glass to glass laminations or if I were bonding epoxy
to epoxy.

Any suggestions on a really strong way to fix holes in polyester
laminated structures or improvements on what Im already doing would be
appreciated.

Regards,

wh

Hello:

In my probably distorted brain the 'view' is that polyester bonds well to
itself and only so-so to other materials (lots of first and second hand
experience of polyester resin to wood failures after about 8 to 10 years),
but epoxy bonds well to lots of things, including polyester.

paul
www.epoxyproducts.com/marine.html


--


================================================== =====
PAUL OMAN ----- Progressive Epoxy Polymers, Inc.
Frog Pond Hollow - 48 Wildwood Dr - Pittsfield NH 03263
603-435-7199 FAX 603-435-7182 VISA/MC/Discover
http://www.epoxyproducts.com
Boating site: http://www.epoxyproducts.com/marine.html
================================================== ======

I believe epoxy bonds to cured poly better than poly to cured poly, but
it's been so long I'm not sure. Any chemists out there?

Ron

On Wed, 16 Jul 2003 22:53:28 -0400 (EDT), (Ron
Thornton) wrote:

I believe epoxy bonds to cured poly better than poly to cured poly, but
it's been so long I'm not sure. Any chemists out there?

Ron

Once its cured its all the same - its just another surface.
But epoxy would have the better flow, as a wetting agent, ionic.

So better able to get into all the scratches etc -so its about its
mechanical ability to flood the surface area completely.
While poly is a bit lumpy as in viscosity

But you can test it by sticking a piece of paper in both see how they
climb. Or a measured drop on paper and see which makes the biggest
circle, for spread, That kind of testing will give comparisons. plus
others.
I have stuck stuff with poly, its okay - but its not considered an
adhesive as epoxy.

Thanks Rubbish,

I guess that's why we went to such extreme to make the surface rough for
poly when it was the only reasonably priced resin. Trying to make a
silk purse out of a sows ear I suppose.

Ron