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!=-

"ddinc" wrote in
:

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!

I believe you missed the point completely. The discussion is REPAIRING a
polyester NOT building one. Even most neophytes are aware of what and
how the majority of boats are made. sheesh!

Now back to the topic, I repeat, only idiots and shadetree bubbas (or an
emergency repair) ever use polyester to repaair polyester. I will leave
the details to the jillions of works on the subject.

--
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!=-

"ddinc" wrote in message
...
99 % of ALL composite boats built are polyester to polyester.

Sure, and the layup is wet in wet. Now try the same on old and dry
polyester...

Meindert

MonteP wrote:

(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!

-------------

Epoxy sticks well to most surfaces but polyester sticks well really only to
polyester, so to my knowledge it is OK to do the repair with the polyester
resin (it is not like you're crossing oceans in this boat!).

Folks like epoxy because it is better than polyester in many ways and a lot
of folks like to 'go up a notch or two' when repairing things.

Personally, I would use the polyester on the dinghy if I had the poly in the
house (and that's from an epoxy salesman!)


paul oman
www.epoxyproducts.com/marine.html

MonteP wrote in message news:

ALL sources say polyester to polyester is not recommended. Use Epoxy
for all repairs of polyester. PERIOD!
I repeat, only idiots and shadetree bubbas (or an
emergency repair) ever use polyester to repaair polyester. I will leave
the details to the jillions of works on the subject.

Monte,

could you provide references for one or two readily available sources
that support your view? I've never had a problem with polyester to
polyester boat repairs. The polyester products I purchased provided
instructions for this type of repair.

So, I'm genuinely curious and open to learning something new.

Thank you very much,
Dave Wright

On 21 Oct 2004 12:49:27 -0700, (Dave Wright)
wrote:

MonteP wrote in message news:

ALL sources say polyester to polyester is not recommended. Use Epoxy
for all repairs of polyester. PERIOD!
I repeat, only idiots and shadetree bubbas (or an
emergency repair) ever use polyester to repaair polyester. I will leave
the details to the jillions of works on the subject.

Monte,

could you provide references for one or two readily available sources
that support your view? I've never had a problem with polyester to
polyester boat repairs. The polyester products I purchased provided
instructions for this type of repair.

So, I'm genuinely curious and open to learning something new.

Thank you very much,
Dave Wright

Here was my experience, for what it's worth:
I have used glass/polyester on old car bodies, in the long-ago.

So without much thought about it, I applied glass/polyester bandaids
to several spots on an older bass-boat, and covered them with
stretched cling-film taped to the hull so as to provide a fair smooth
surface.

The patches looked good, but after several seasons use, I noticed
that the patches were showing a milky interface, and appeared to be
leaking somewhat.

I will try glass epoxy with cling film, next time I need to.

Brian W

Here was my experience, for what it's worth:
I have used glass/polyester on old car bodies, in the long-ago.

So without much thought about it, I applied glass/polyester bandaids
to several spots on an older bass-boat, and covered them with
stretched cling-film taped to the hull so as to provide a fair smooth
surface.

The patches looked good, but after several seasons use, I noticed
that the patches were showing a milky interface, and appeared to be
leaking somewhat.

I will try glass epoxy with cling film, next time I need to.

Brian W


Brian, I like epoxy a lot and never had a problem with epoxy. But I've
also had success with polyester resins too. It often depends on the
type of polyester resin you're using; the isophthalic polyester resins
are better than the ortho-polyester resins. If you attempt the repair
with polyester resin again, maybe after coarse grinding (36 grit),
wash the old laminate down with styrene (folks often seem to use
acetone), it may soften the base somewhat better than acetone and help
to give you a decent secondary bond.

You might find that you can get vinylester resin (5% elong. @ 11,800
psi) cheaper than epoxy (5% elong. @ 12,500 psi). I would guess that
every day knowledgeable technicians evaluate polyester based resin
boats for repair or modification. The goal generally is to produce a
satisfactory repair for the remaining life of the boat at the lowest
cost. It's good to try various materials and methods, especially on
small jobs. If they don't work, try something else. Since all of
these materials are application, process, material, and operator
sensitive, it's sometimes hard to acertain why one individual might
have success and another failure.

Best wishes to everyone in their repair jobs.

Dave Wright