Polyester or epoxy resin
 

My old Nautilus 8 Dinghy was damaged by Ivan and has a sizeable hole
in the side. I have some polyester resin on hand and I am wondering
if I can use it instead of expensive epoxy for a repair. Other than
some sanding, how do I prepare the surface to make sure the resin
adheres. The dinghy is at least 25 yrs old so is very weathered.

Parallax wrote:

My old Nautilus 8 Dinghy was damaged by Ivan and has a sizeable hole
in the side. I have some polyester resin on hand and I am wondering
if I can use it instead of expensive epoxy for a repair. Other than
some sanding, how do I prepare the surface to make sure the resin
adheres. The dinghy is at least 25 yrs old so is very weathered.

After sanding, wash with a rag wetted with acetone to remove any
leftover wax. Coarse sand and slop it to 'er.

Epoxy is technically better, but poly will do fine.

Terry K

a good place to go is the public library. if they don't have any books
on fibreglass boat repair look for a book on auto body maintenance.

Parallax ) writes:
My old Nautilus 8 Dinghy was damaged by Ivan and has a sizeable hole
in the side. I have some polyester resin on hand and I am wondering
if I can use it instead of expensive epoxy for a repair. Other than
some sanding, how do I prepare the surface to make sure the resin
adheres. The dinghy is at least 25 yrs old so is very weathered.


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William R Watt National Capital FreeNet Ottawa's free community network
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I agree 100%. Over the years I repaired several polyester boats with
polyester. Cleaned with acetone and washed down. Feathered the edges and
sanded as recommended and carefully laid the glass. EVERY one of them
started peeling within a few months. Five years ago I changed to epoxy.
Not a single failure of any kinde ever since.


MonteP wrote in message
.. .
(Parallax) wrote in
om:

My old Nautilus 8 Dinghy was damaged by Ivan and has a sizeable hole
in the side. I have some polyester resin on hand and I am wondering
if I can use it instead of expensive epoxy for a repair. Other than
some sanding, how do I prepare the surface to make sure the resin
adheres. The dinghy is at least 25 yrs old so is very weathered.

HAving repaired more than a few I would make note of the fact that ALL
sources say polyester to polyester is not recommended. Use Epoxy for all
repairs of polyester. PERIOD!

--
MonteP
"Against stupidity, the very gods themselves contend in vain." -
Friedrich von Schiller
"Ignorant voracity -- a wingless vulture -- can soar only into the depths
of ignominy." Patrick O'Brian
-=The answer is simple...send pretzels to the Whitehouse!=-

must be the water or the weather down there in Gerogia. no problems here.
polyester predates epoxy by decades. polyester on polyester repairs are fine.
the only "sources" who insist on epxoy are the sources selling epoxy.

"Glenn Ashmore" ) writes:
I agree 100%. Over the years I repaired several polyester boats with
polyester. Cleaned with acetone and washed down. Feathered the edges and
sanded as recommended and carefully laid the glass. EVERY one of them
started peeling within a few months. Five years ago I changed to epoxy.
Not a single failure of any kinde ever since.


MonteP wrote in message
.. .
(Parallax) wrote in
om:

My old Nautilus 8 Dinghy was damaged by Ivan and has a sizeable hole
in the side. I have some polyester resin on hand and I am wondering
if I can use it instead of expensive epoxy for a repair. Other than
some sanding, how do I prepare the surface to make sure the resin
adheres. The dinghy is at least 25 yrs old so is very weathered.

HAving repaired more than a few I would make note of the fact that ALL
sources say polyester to polyester is not recommended. Use Epoxy for all
repairs of polyester. PERIOD!

--
MonteP
"Against stupidity, the very gods themselves contend in vain." -
Friedrich von Schiller
"Ignorant voracity -- a wingless vulture -- can soar only into the depths
of ignominy." Patrick O'Brian
-=The answer is simple...send pretzels to the Whitehouse!=-




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William R Watt National Capital FreeNet Ottawa's free community network
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upon reflection I see some differences.

I've never used acetone to clean an area before applying a patch. I'd stay
away from any kind of solvent. I brush the sanded area to get rid of any
sanding dust, and then blow in it.

I also go for a slow cure. I suspect a fast cure would not bond as well.
That may be a problem in the south. I'd use less than the prescribed
amount of catalyst in hot weather. Never had that problme up here. I'd
also work in the shade or on an overcast day down there, just like when
applying varnish.

hope that helps

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William R Watt National Capital FreeNet Ottawa's free community network
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I do the acetone wash to the area to be patched before doing anything to get
rid of any wax or other contaminants so that they will not be ground into
the bonding surface grinding and feathering.

Most of the repairs have been done on those cheap chopper gunned fiberglass
duck boats that Sears sells. My brother and his hunting friends don't treat
them with much respect. I think what happens is that they drag them out of
their pickups and let the ends hit the ground. That causes cracks at the
chines and transom. Polyester patches last about 3 or 4 drops and start to
peel. After I switched to epoxy I have had no failures.

I'm just glad to get them out of my hair. I have enough to do on Rutu
without being the resident repair expert for every duck hunting crappie
fisherman in the neighborhood. Especially when they figure a six pack is
fair payment. :-)
"William R. Watt" wrote in message
...

upon reflection I see some differences.

I've never used acetone to clean an area before applying a patch. I'd stay
away from any kind of solvent. I brush the sanded area to get rid of any
sanding dust, and then blow in it.

I also go for a slow cure. I suspect a fast cure would not bond as well.
That may be a problem in the south. I'd use less than the prescribed
amount of catalyst in hot weather. Never had that problme up here. I'd
also work in the shade or on an overcast day down there, just like when
applying varnish.

hope that helps

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William R Watt National Capital FreeNet Ottawa's free community
network
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"Glenn Ashmore" ) writes:

.... I think what happens is that they drag them out of
their pickups and let the ends hit the ground. That causes cracks at the
chines and transom. Polyester patches last about 3 or 4 drops and start to
peel. After I switched to epoxy I have had no failures.

I think I would have bolted angle iron all around the edges. :)



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William R Watt National Capital FreeNet Ottawa's free community network
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99 % of ALL composite boats built are polyester to polyester.

MonteP wrote in message
.. .
(Parallax) wrote in
om:

My old Nautilus 8 Dinghy was damaged by Ivan and has a sizeable hole
in the side. I have some polyester resin on hand and I am wondering
if I can use it instead of expensive epoxy for a repair. Other than
some sanding, how do I prepare the surface to make sure the resin
adheres. The dinghy is at least 25 yrs old so is very weathered.

HAving repaired more than a few I would make note of the fact that ALL
sources say polyester to polyester is not recommended. Use Epoxy for all
repairs of polyester. PERIOD!

--
MonteP
"Against stupidity, the very gods themselves contend in vain." -
Friedrich von Schiller
"Ignorant voracity -- a wingless vulture -- can soar only into the depths
of ignominy." Patrick O'Brian
-=The answer is simple...send pretzels to the Whitehouse!=-