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Old 06-04-2018, 21:56   #16
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

This is just more evidence that epoxy and wood shouldn’t be mixed if it can’t be applied in a controlled environment and/or can’t be kept out of the sun. Too late I read Pardey’s Appendix C in his hull construction book after I had already done what you have done. I’m waiting to watch my masts do the same as yours, although I didn’t use glass and worked on them in my sunroom. Depressing. Marine epoxy: caveat emptor. I will never use the stuff on my wooden boat again.
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Old 06-04-2018, 22:00   #17
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

I have to agree with Pauls. You are fighting UV degradation.

I work with epoxy every day. I have personally used several hundred gallons of epoxy and I put it on with fiberglass cloth over wood just like you have done. My work, however, stays indoors or gets covered from UV. But, if I leave it outside, even here in Ohio (which is not tropical sun), I have had the exact same problem (3-4 months here).

My work has been exposed to freeze, rough treatment, hot water, and chemicals without any problems, but the sun will eat it up.

There is a chance that you are experiencing 'creep' in the epoxy, but I doubt it. Most room-temperature epoxies will start to soften around 150 F or so. This can let the epoxy slowly creep where it seemed hard and stable before. But... I really don't believe that is your problem.

From the pictures you have shown, this little bit of UV damage is not going to hurt the strength. I would leave it alone rather than sand through the fiberglass cloth. (You can never fully get that strength back.) Then I would scruff it and coat it with a good quality white paint. That is the only real protection you're going to get from the sun.

If you want the wood look, then you're going to have to sand off all of the fiberglass and apply multiple layers of a good varnish. Personally, I would go with the paint. Just saying.

I'm putting up a picture of my work, not for advertising, just to show you the work I'm talking about. (This is West System over S-Glass.)

I hope this helps.

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Old 06-04-2018, 22:34   #18
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

Mixing us a crucial part of the project.apparently the the ratio is such that the epoxy and hardener have specific particles that are disignated with each other as the ratio is specified
That being said once added try to get as much out of the mixing pots as possisle even pouring back into the original pots because there is always more residue left behind than one realises. ..but more and more sounds like moisture from somewhere.
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Old 08-04-2018, 06:24   #19
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

Most of the reponses here look pretty good.

1. Could be hydrostatic force of moisture rising / evaporating from wood. Would expect this to cause widespread delamination between wood and hardened epoxy.

2. Could be UV damage to epoxy. Would expect this to cause consistent opaque appearance.

3. But to me it sounds like a chemical incompatibility. You have not mentioned the type of glass used. Is it really chopped strand mat? Most of these contain binders that are incompatible with epoxy, and could produce results consistent with what you are experiencing. To get epoxy compatible CSM, you have to ensure it indicates so on the label or spec sheet.
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Old 08-04-2018, 07:37   #20
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

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Originally Posted by ramblinrod View Post
Most of the reponses here look pretty good.

1. Could be hydrostatic force of moisture rising / evaporating from wood. Would expect this to cause widespread delamination between wood and hardened epoxy.

2. Could be UV damage to epoxy. Would expect this to cause consistent opaque appearance.

3. But to me it sounds like a chemical incompatibility. You have not mentioned the type of glass used. Is it really chopped strand mat? Most of these contain binders that are incompatible with epoxy, and could produce results consistent with what you are experiencing. To get epoxy compatible CSM, you have to ensure it indicates so on the label or spec sheet.
Upon re-reading the original post, UV degradation and moisture hydrostatic pressure are pretty much ruled out, as it is only occurring where glass meets epoxy. For UV or moisture, it would most likely occur only on sunlight exposed side, but over whole length. Which really re-affirms # 3, incompatibility between glass and epoxy.
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Old 08-04-2018, 07:48   #21
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

One last thing, I teach DIY fibreglass seminars at marine retailers and yacht clubs.

When working with epoxy, follow safety precautions religiously. 30 years ago, there was very little info about epoxy sensitization and contact dermatitis. Recently, West Systems put a fairly comprehensive section about it on their website "safety" page.

I won't sand the stuff, without wearing a full hazmat suit and organic vapour full mask.

Overkill?

No, I have seen people develop epoxy sensitivity and it ain't pretty. (And it precludes one from ever going near curing (up to 2 weeks or even longer) again.

For these reasons, I avoid using epoxy inside boats, where the occupants (in may case customers) may never be able to go in the boat again, if they develop an epoxy sensitivity. It seems to only happen to about 2% of the population, and one never knows if it will be the result of exposure 1 or 1000.

It would be really bad if I performed work in a boat that resulted in the owner or family member to never be able to enter the boat again.

If the boat is already made of polyester fibreglass, that is what I tend to use, so that I don't introduce a new material that could cause problems.

That said, for wooden mast work, epoxy is the best resin for this application; but as many, including Larry Pardey can attest, it is not as fool proof as many do, or would lead one to, believe.
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Old 08-04-2018, 11:03   #22
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

If it isn't UV degradation then I would question if the fiberglass cloth was compatible with epoxy resin, or even perhaps been contaminated.
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Old 08-04-2018, 16:22   #23
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass



Not sure if I've correctly added the photo of laying up the most recent (and now suspect) fiberglass cloth mast band. I don't know the weight of it, light, and NO mat is being used at all. I have wondered about the cloth itself being the problem after reading online about previously there being two kinds, one for resin the other for epoxy compatible use, but more currently there are cloths friendly to both. There was only one kind offered in the local hardware store I purchased it from. I am gratified to have it noted that nowhere else on the spars is there any sign of UV problems.

As to the varnish...it is a urethane, one part, thin to lay on. It is Spar Varnish but who knows if there's truth in that when manufacturing in the Philippines. I have always put a minimum of seven coats on whatever I varnish, immediately, then have been fairly religious about buildup coats every three-four months. With this thinner spar varnish I'd thought to try for something closer to the 14 coats the old timers used as a standard. So far, only three to four coats have been applied. Lots to do. Slow sanding, in sections, then moving saw horses to sand and varnish when the previous is dry enough to not be damaged.

Lots to think about here. We've started grinding, will go back to wood and do it over, using all the suggestions everyone has been so generous to offer--as well as checking further about the glass itself...or possibly condensation in the epoxy can? We're almost to the bottom of it...maybe that's possible?
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Old 09-04-2018, 07:53   #24
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

Regarding the glass compatability with the epoxy you are using, what we're talking about is the sizing applied to the glass fibers. Sizing is a coating applied to the fibers which can improve fiber to resin bonding. There are literally hundreds of different sizings, companies which buy large quantities of glass can have custom sizings developed for their application. You don't need to worry about that level of detail. But what you do need is glass with a sizing which is basically epoxy compatable. I don't recall the details as to which sizings are best for epoxy but a little web research will pull up the details. As to whether your supplier in the PI will have any info on the sizing of the cloth he is selling?

Your application is not demanding at all. If the cloth wets out OK and a sample cures and looks good they you're going to be fine.

Your picture shows the glass being applied over the varnished wood. I think that is the source of your problem. Glass over varnish is a big error for two reasons. #1, the varnish is going to continue to outgas for a long time and when the glass is laid over the top of it the outgassing is trapped. I would guess that is the source of your opaque areas. #2, the epoxy bond to the varnish is weak. The epoxy will bond much more strongly to bare wood which allows the epoxy resin to sink into the wood grain. My recommendation is to remove the existing glass and sand down to clean bare wood in the area you'll be glassing. Lay in new glass on the bare wood. After sufficient curing time, paint the glassed area with a tough light colored paint, tough to resist wear from the gaff jaws/saddle and light colored to keep temperatures down in the tropics. The epoxy you will be using will thermally degrade if you do not use a light colored paint, and white is by far the best. Varnish the bare wood up to the edge of the glass after the epoxy has cured. I think you'll like the results and this approach and it will be the most durable and long lasting.
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Old 09-04-2018, 14:20   #25
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

I can't thank everyone enough for all the continuing good advice and support.

Yesterday I talked again with the local epoxy expert about the cloth. He acknowledged that the store where we both purchased glass cloth sometimes stocks the saline coated kind for use with resin, and sometimes their stock is not coated, which is suitable for use with epoxy. "Hard to know the difference" he said, but the latter is softer, less stiff. He buys it in bulk when they have it as they don't stock both kinds at the same time, and gave me a sample.

The cloth we've used was purchased twice, first, November 2017, then again this year in March, when we replaced the layup we'd made in January when it began showing problems. Comparing his sample cloth to our two bags of remnant cloth from both purchases, it was difficult to tell the difference but it did seem that the November cloth was a bit stiffer.

In the meantime, the five mast bands have already been ground down to almost wood. Hand sanding will take them further, then we will again lay them up with all the precautions suggested.

Pauls, no worries about epoxying over varnish. We didn't, and won't. And, of course everyone is absolutely correct about paint being far superior varnish for UV protection. I will give it serious consideration, but stubbornly have to say that for all these years--since 1985--varnish has protected the original bands, epoxied, with no problems to them other than the couple of times I let the varnish get away from me and had to strip the masts, start over again. Glutton for punishment, obviously.

I will, however, humbly admit and beg forgiveness when/if this new spar varnish, a urethane, fails to protect. Already, though, I rue (like Bailsout) having given up my Luddite love for the old ways of a simpler oil-based coating.
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Old 09-04-2018, 15:11   #26
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

Hey Gaffer,

Just looked at your profile. What a beautiful boat. And you're doing nice work on the rebuild.

I'm building a 42' gaff rig cutter, double ended, steel. Maybe I'll see you out there one of these years.

Regards,

Paul
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Old 26-04-2018, 14:01   #27
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

Quote:
Originally Posted by Terra Nova View Post
If it isn't UV degradation then I would question if the fiberglass cloth was compatible with epoxy resin, or even perhaps been contaminated.
Hello I have seen this when cloth has got contaminated also as the resin doesnt
appear to saturate cloth perhaps wax or some other sizing agent .Nice work beautiful boat hope to see more...
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Old 28-04-2018, 19:19   #28
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

Thanks so much for your interest and compliments, Paul & Mistress Sirena (as well as all those before, too!).

The attached photo was taken yesterday, as the third coat of spar varnish was brushed onto the three layers of fiberglass and epoxy--carefully following the invaluable advice from everyone--so next week we can resume applying the multiple coats needed for future UV protection, when out from under the awning.

I will post again when the masts are back in PILAR. Had not dreamed, almost a year ago (Mother's Day, 2017) that it would be over a year before that happened!
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Old 30-04-2018, 06:50   #29
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Re: Urgent Advice needed - 2Months later, ’dry’ spots in epoxy/fiberglass

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