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Old 03-01-2017, 20:30   #76
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Re: glassing plywood prior to hull installation

Seems to be an awful lot of misinformation being spread by supposed marine professionals.
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Old 03-01-2017, 20:43   #77
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Re: glassing plywood prior to hull installation

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Originally Posted by Scout 30 View Post
Once again you're off the mark. Pretty much no fiberglass boat builders use wood anymore due to the well known problems of water intrusion & rot. In fact that's a big selling point these days. Try again.
Again, I have been very clear about my experience building and repairing with polyester resin FRP.

What's yours?
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Old 03-01-2017, 22:18   #78
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Re: glassing plywood prior to hull installation

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Originally Posted by ramblinrod View Post
Again, I have been very clear about my experience building and repairing with polyester resin FRP.

What's yours?
And yet you don't know enough to wear gloves when working with epoxy. If you truly are a professional you don't appear to be much of one.
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Old 04-01-2017, 05:51   #79
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Re: glassing plywood prior to hull installation

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And yet you don't know enough to wear gloves when working with epoxy. If you truly are a professional you don't appear to be much of one.
What is your your first hand experience level with polyester resin?
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Old 04-01-2017, 06:34   #80
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Re: glassing plywood prior to hull installation

So here's a photo from one of my seminars during an epoxy FRP repair demo.



They are sold out months in advance with a waiting list typically double the audience limit (30 people).

I conduct them for local marine retailers and yacht clubs every year, to help DIYers repair their boats properly and safely.

Normally, I don't touch the stuff without wearing a full hazmat suit, and full detail of proper protective gear is part of the discussion, but it takes too long to suit up and the audience can't hear me through an organic respirator, so I risk my health for the benefit of teaching others about proper epoxy application.

At the same time, I teach about the proper use of polyester resin, and how to make effective repairs with it, typically with numerous before and after photos.

This photo illustrates the typical hazmat suit I normally wear while working with epoxy.

Here, I am applying the second coat of an ablative anti-fouling paint.

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Old 04-01-2017, 08:21   #81
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Re: glassing plywood prior to hull installation

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Originally Posted by Scout 30 View Post
And yet you don't know enough to wear gloves when working with epoxy. If you truly are a professional you don't appear to be much of one.
I have no professional experience with epoxy and other two part formulas. Just built a couple of dinks and helped a friend a little with the build of a 65 foot cat. that turned out very nice. My opinion is that while epoxy is better there are applications that using something else is not a disaster waiting to happen.

In most threads I usually find Scout 30's comments worth consideration. Plus I think your boat is really cool..... But he obviously wears gloves..... I have an aquaintence that developed an allergy to epoxy that is severe. He always used gloves and suit. He can't even be around the fumes now.

Rod asked several times, what personal experience do you have?
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Old 04-01-2017, 08:45   #82
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Re: glassing plywood prior to hull installation

Some people are very sensitive to epoxy, and so must wear protection. Most of us are not sensitive to it.

I am a marine professional and have used barrels of WEST epoxy, mostly for glue-ups, tabbing and coating. I fortunately am not sensitive to it, and typically work with no protection other than a dust mask, while sanding--not even gloves, unless doing a large layup, where I must handle large pieces of wetted out biaxial. The trick is to not get it on you and, once you have, to immediately remove the contamination; for this I use paper towels, often moistened with acetone.

I have seen and/or repaired delaminated polyester/wood bulkhead tabbing on numerous boats. And so would NEVER use polyester resin for this critical application.
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Old 04-01-2017, 10:16   #83
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Re: glassing plywood prior to hull installation

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Originally Posted by Terra Nova View Post
Some people are very sensitive to epoxy, and so must wear protection. Most of us are not sensitive to it.

I am a marine professional and have used barrels of WEST epoxy, mostly for glue-ups, tabbing and coating. I fortunately am not sensitive to it, and typically work with no protection other than a dust mask, while sanding--not even gloves, unless doing a large layup, where I must handle large pieces of wetted out biaxial. The trick is to not get it on you and, once you have, to immediately remove the contamination; for this I use paper towels, often moistened with acetone.

I have seen and/or repaired delaminated polyester/wood bulkhead tabbing on numerous boats. And so would NEVER use polyester resin for this critical application.
At last, someone with some experience.

I too have repaired polyester tabbing failures, that have occurred due to poor design, application, vessel use, or just simple wear and tear.

I have also repaired epoxy tabbing failures, for all the same reasons.

There are all kinds of claims all over the internet regarding epoxy vs polyester. Many that proclaim significant advantages of epoxy over polyester, are affiliated with epoxy manufacturers.

In my experience, properly applied polyester resin in a secondary mechanical bond, is as strong, or stronger than the materials bonded whether wood or polyester FRP.

I suspect some of the difficulties some DIYers experience with poor adhesion is from using box store polyester resin products that contain wax to facilitate curing in air.

Similarly if one adds wax to epoxy, poor adhesion results will occur.

As I have stated before, I tend to make repairs with polyester where I can, for a variety of reasons. When I require its max adhesive properties, I use unwaxed resin and then a proper method to facilitate curing in air if required (peel ply, gelcoat, wax paper, wax curing agent in final resin rich coat, etc.)

If the naval architect and engineers specified polyester, that is what I use.

If they specified epoxy (very rare) that is what I use.

I will warn that one can use epoxy with no ill effects for years, and then one day, out of the blue, flair up, and from that day forward, can't go near it. I've seen 3 different people who have had this happen.

For some, this can happen first use, for others, no sign whatsoever, until one day...

Epoxy is made with known carcinogens. One should always use an organic mask when working with uncured and cured materials.

During curing, various toxic gases are emitted. People are lured into believing they are safe, because the smell is not offensive to them. Incorrect!

Even for cured material, the cutting and sanding process causes the material to heat up, releasing carcinogenic vapours that can permeate the highest quality dust mask, which are typically rated to only filter 95% of hazardous particulate. Toxic vapours permeate without any real restriction.

The best rule of thumb when working with epoxy and other hazardous materials; if you can smell it, your mask is not working, and harmful vapours are entering your lungs.

Be safe, this is a recreational sport and not worth risking health over.

For me, this is part of my livelihood (I perform all manner of yacht repair, maintenance, and improvement, fibreglass being about 25%), and I am careful not to needlessly risk my health over it.

It is very wise to read the MSDS for any material worked with, and follow the safety precautions specified. If in doubt, err on the side of caution.

I had one prospect complain about my hazardous material rate for a teak deck acid wash. "I've used that stuff wearing nothing but shorts and a T-shirt", he claimed. As he told me this he was being treated for Stage 3 cancer.

Stay safe.
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Old 04-01-2017, 10:42   #84
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Re: glassing plywood prior to hull installation

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Despite popular belief and all the marketing bestowed on DIYers by epoxy manufacturers, results are actually superior using polyester resin (and it is way less expensive).

I'm sorry but if this were true I'm sure custom builders like Jarrett Bay would be using polyester rather than epoxy to construct their cold molded boats. Polyesters properties for adhering to wood are far inferior to epoxies. That I'm sorry is a well known fact.


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Old 04-01-2017, 10:47   #85
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Re: glassing plywood prior to hull installation

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Originally Posted by ramblinrod View Post

Similarly if one adds wax to epoxy, poor adhesion results will occur.
Why the hell would anyone do that?
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Old 04-01-2017, 10:53   #86
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Re: glassing plywood prior to hull installation

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If the naval architect and engineers specified polyester, that is what I use.
Just because the original build was polyester doesn't mean that polyester is the best material for repair when the original is not green - in other words after about one month.
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Old 04-01-2017, 12:12   #87
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Re: glassing plywood prior to hull installation

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Why the hell would anyone do that?
They wouldn't of course; using a waxed polyester for adhering to wood or for
seconday mechanical bond repair is equally wrong. Yet plenty do it and then pronounce the poor adhesive qualities of polyester resin.
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Old 04-01-2017, 14:35   #88
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Re: glassing plywood prior to hull installation

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Originally Posted by mitiempo View Post
Just because the original build was polyester doesn't mean that polyester is the best material for repair when the original is not green - in other words after about one month.
I agree completely.

If the original spec is polyester, polyester is adequate for the repair, and after weighing all of the pros cons, including cost, curing temperature sensitivity, safety, UV resistance, gelcoat compatibility, etc, polyester is the better solution, that is the material I use and recommend.

My point is, many people believe epoxy is the only solution, and use it, when polyester may have been the better choice, ALL things considered.

I have made 1000s of successful polyester FRP secondary mechanical bond adhesions for repair and original construction. Zero failures. Ever. Not one.

Lots of manufacturers too.
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Old 04-01-2017, 14:41   #89
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Re: glassing plywood prior to hull installation

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Originally Posted by ramblinrod View Post
I agree completely.



If the original spec is polyester, polyester is adequate for the repair, and after weighing all of the pros cons, including cost, curing temperature sensitivity, safety, UV resistance, gelcoat compatibility, etc, polyester is the better solution, that is the material I use and recommend.



My point is, many people believe epoxy is the only solution, and use it, when polyester may have been the better choice, ALL things considered.



I have made 1000s of successful polyester FRP secondary mechanical bond adhesions for repair and original construction. Zero failures. Ever. Not one.



Lots of manufacturers too.

When making a repair to a boat, especially structural, the added cost of epoxy should be negligible and shouldn't even be a factor.
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Old 04-01-2017, 16:04   #90
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Re: glassing plywood prior to hull installation

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When making a repair to a boat, especially structural, the added cost of epoxy should be negligible and shouldn't even be a factor.
I agree. The labor is the same whether epoxy or polyester is used.

Polyester is not that great at secondary bonding - epoxy excels at this.
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