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Old 25-03-2020, 21:38   #31
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Re: Does my hull still need a barrier coat

Quote:
Originally Posted by Steve DAntonio View Post
When I managed a yard I supervised well over a hundred peel and re-lamination jobs, our preferred material was vinylester resin and fairing compounds as it's every bit as effective as epoxy, but easier to work with. Regardless, provided the skin coat is thick enough, 1/10" is required for VE, VE and epoxy are for the most part immune to osmotic blisters, so strictly speaking no barrier is needed. However, we still applied a barrier, Interlux Interprotect 2000 for two reasons, one it was a belt and suspenders approach (we offered a 10 year warranty against reappearance of blisters, one we never had to act on in my 11 years there), and two, the barrier is an excellent primer for anti-fouling paint, far better than the cured epoxy or VE resin, or fairing. If the bottom paint is applied within the chemical application window, you will achieve a chemical bond, which is more tenacious than the mechanical bond achieved by sanding applying anti-fouling paint over a cured surface like gelcoat or VE/epoxy resin. In short, the barrier adheres to the new bottom very well, and the bottom paint adheres to the barrier very well. The bottom still needs to be profiled before applying the barrier. Use anti-foulant that is made by Interlux and known to be compatible with Interprotect, there are many from which to choose, my preference is for an ablative.

Interprotect says that if Interprotect 2000 is used as a barrier you need roughly five rolled on coats (we applied with an airless to achieve 10 mils dry, and a very smooth finish). If used strictly as a primer, only 1-2 coats are needed, but once geared up I'd recommend the full 10 mils. Instructions here http://www.yachtpaint.com/MPYACMData...Y+20141215.pdf

This article describes the process https://stevedmarineconsulting.com/w...nd-Osmosis.pdf

On the subject of osmosis repairs in general...polyester resin and polyester based gelcoats are poor barriers to moisture (isophthalic or iso resin is more blister resistant than orthophthalic resin, but it's not blister-proof), however, it's not that simple, as the above article explains, water migration into the laminate is just the first step in the process, once the water is there if it then encounters water soluble materials or WSMs, usually starch-based binders, the reaction that ensues creates pressure, and the symptom, blisters. I've encountered boats with bottoms that pegged a moisture meter and yet had no blisters, and I've encountered moderately wet bottoms that were riddled with blisters.
Furthermore, based on my first hand experience and research, for two reasons it is impossible to "dry out" a bottom that has absorbed moisture. One, two of the byproducts of osmosis are acetic acid (that why burst blisters small like vinegar) and glycol, neither of which evaporate at atmospheric pressure, so even if you can get water to evaporate from a FRP laminate, admittedly a stretch, these chemicals will remain, and continue to react with the WSMs. The acetic acid also attacks resin, causing "fiber whiting" which, when peeled, is often mistaken for incomplete wet-out, the acid is in fact slowly disassembling the resin's structure.

Please don't let anyone charge you to remove gelcoat, "dry" a bottom with tenting and dehumidifiers, individually fix blisters, and barrier coat, at least not as anything other than a short term, cosmetic fix. If an osmosis repair doesn't include at least a 5, and preferably 10, year warranty, it's probably not going to be long-lasting. Again, you may still choose that route, as long as you understand that going in. Those quick "repairs" should be far less expensive than a full peel (and the peel must go down to unaffected laminate, that's determined with a patch test, see the article), which is laborious and requires significant skill. It must also include removal of all bottom hardware, thru-hulls, strut etc, to achieve a proper peel and re-lamination.
Thank you for that article. It was very informative and confirmed my research prior to starting this project.

I have peeled my bottom twice. The first peel removed the layers of bottom paint and what appeared to be a previous failed blister repair as there was what looked like fairing material under the barrier coat and blistering below that. The next peel removed almost all the CSM. I have pressure washed the hull about 12 times and it has sat peeled now for over 18 months. Moisture levels have dropped to almostst the same readings as the newly laid decks.

I recently sandblasted the surface to give the hull a nice profile for bonding and if it will stop raining here in California, I should be glassing the hull very soon. I would love to hear some pro tips on working with large pieces of fiberglass basically upside down! It's one thing to wet out 10 feet of 50" biax on a deck, it's a whole another thing doing it on the hull, I'm sure.

My original plan was to use vinylester, as I re-cored and then glassed my decks with it. I have since decided to go with epoxy for the extended working time it provides. If we were an experienced crew vinyl ester probably wouldn't be a problem but sometimes, I am the only one working on this.

Thanks for all the responses.
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Old 26-03-2020, 07:30   #32
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Re: Does my hull still need a barrier coat

Quote:
Originally Posted by Wind River View Post
Thank you for that article. It was very informative and confirmed my research prior to starting this project.

I have peeled my bottom twice. The first peel removed the layers of bottom paint and what appeared to be a previous failed blister repair as there was what looked like fairing material under the barrier coat and blistering below that. The next peel removed almost all the CSM. I have pressure washed the hull about 12 times and it has sat peeled now for over 18 months. Moisture levels have dropped to almostst the same readings as the newly laid decks.

I recently sandblasted the surface to give the hull a nice profile for bonding and if it will stop raining here in California, I should be glassing the hull very soon. I would love to hear some pro tips on working with large pieces of fiberglass basically upside down! It's one thing to wet out 10 feet of 50" biax on a deck, it's a whole another thing doing it on the hull, I'm sure.

My original plan was to use vinylester, as I re-cored and then glassed my decks with it. I have since decided to go with epoxy for the extended working time it provides. If we were an experienced crew vinyl ester probably wouldn't be a problem but sometimes, I am the only one working on this.

Thanks for all the responses.
Do you watch Youtube? The channel “sail life” has an episode where they show glassing the bottom. Even for projects I have done before, I always check Youtube because often someone else found a better way
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Old 26-03-2020, 09:51   #33
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Re: Does my hull still need a barrier coat

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Originally Posted by s/v Jedi View Post
Do you watch Youtube? The channel “sail life” has an episode where they show glassing the bottom. Even for projects I have done before, I always check Youtube because often someone else found a better way
I watch Mads videos (Sail Life) every Sunday! I'll go back and look at the one he did on glassing his hull again. It's been a while since that one came out.

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Old 26-03-2020, 18:12   #34
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Re: Does my hull still need a barrier coat

Quote:
Originally Posted by Wind River View Post
Thank you for that article. It was very informative and confirmed my research prior to starting this project.

I have peeled my bottom twice. The first peel removed the layers of bottom paint and what appeared to be a previous failed blister repair as there was what looked like fairing material under the barrier coat and blistering below that. The next peel removed almost all the CSM. I have pressure washed the hull about 12 times and it has sat peeled now for over 18 months. Moisture levels have dropped to almostst the same readings as the newly laid decks.

I recently sandblasted the surface to give the hull a nice profile for bonding and if it will stop raining here in California, I should be glassing the hull very soon. I would love to hear some pro tips on working with large pieces of fiberglass basically upside down! It's one thing to wet out 10 feet of 50" biax on a deck, it's a whole another thing doing it on the hull, I'm sure.

My original plan was to use vinylester, as I re-cored and then glassed my decks with it. I have since decided to go with epoxy for the extended working time it provides. If we were an experienced crew vinyl ester probably wouldn't be a problem but sometimes, I am the only one working on this.

Thanks for all the responses.
Apologies for belaboring this, however, if you have not removed/peeled all the affected, wet laminate, and you are waiting for moisture levels to drop, there is a chance blisters will reappear after the project is complete. You may be willing to take that risk, and at the risk of repeating myself, again, you cannot "dry" a bottom at atmospheric pressure, as the vapor pressure of acetic acid and glycol prevent this from occurring.

Re-lamination is a two man job. All the sections of fabric need to be pre-cut, numbered, rolled and labeled. You wet out the bottom area, apply a section of fabric one at a time, and wet it out. My experience is with VE, I have never used epoxy to re-laminate a bottom. You need to apply at least two layers, or 1/10" for an effective moisture skin coat. The epoxy is friendlier in that it has no VOC's, so low odor, but much more challenging to apply and wet out, upside down, and harder to sand.

The powder blue material that's being rolled on in the photo is Hawkeye Duratec VE fairing material, (relatively) easy to apply and easy to sand. The bottom must be faired when lamination is complete. If you use epoxy, and epoxy based fairing make sure you have been going to the gym regularly, because sanding it, upside down, is no fun.

Preparation is everything, before you start applying resin, you want everything staged and ready to go. You will need to do some trimming of wet fabric, you use a large shears for that and be ready to clean them with solvent.
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Old 26-03-2020, 18:38   #35
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Re: Does my hull still need a barrier coat

Epoxy fairing compounds are as easy to sand as vinylester and polyester fairing compounds. What is hard to sand is epoxy resins thickened with additives like cabosil, microfiber etc.

You need a product that is rated for use below the waterline. Awlfair, Totalfair etc.
TotalBoat TotalFair Marine Fairing Compound
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Old 26-03-2020, 21:45   #36
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Re: Does my hull still need a barrier coat

I am happy with the low moisture meter readings and I believe I have all the affected laminate removed.

I had planned on at least 2 layers of 1708 which should net .090" which is the same depth I had the peeler set at when I did the first and second peel. I may consider a 3rd layer of glass. I will see how it goes.

Like I mentioned before, the first peel took off years of bottom paint, barrier coat and fairing. The second removed the affected glass. I completely understand that the hull doesn't "dry out" simply by letting stay dry. I noticed a significant drop in moisture readings after a several pressure washes, so I continued with it.

I have a fairing compound mix for the epoxy. If I remember correctly it is some kind of phenolic with a little cabosil to keep it from sagging. I have used it already and it is easy to sand.
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Old Yesterday, 07:44   #37
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Re: Does my hull still need a barrier coat

The use of a pressure washer is a well established technique. It works because it drives the acetic acid off/out of the exposed glass of the surface where some is left after the peeling process (peeling is never perfect and contaminants are always left that need to go before sealing the laminate). This allows it to fully dry.

If there would be visible pockets of CSM left, I would probably do spot removal and fairing of those before applying the new 1708 layers.

When you add 2 layers of 1708, you add so much more strength than the removed CSM, that I would not consider adding more layers. I would only do that when structural laminate is removed.

I think you’re good to go, happy to see people diy this, because imo it is too often that people are scared into hiring it out
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Old Today, 06:20   #38
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Re: Does my hull still need a barrier coat

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Like I mentioned before, the first peel took off years of bottom paint, barrier coat and fairing. The second removed the affected glass. I completely understand that the hull doesn't "dry out" simply by letting stay dry. I noticed a significant drop in moisture readings after a several pressure washes, so I continued with it.

I have a fairing compound mix for the epoxy. If I remember correctly it is some kind of phenolic with a little cabosil to keep it from sagging. I have used it already and it is easy to sand.
Just to be clear, if you "noticed a significant drop in moisture readings after several pressure washes" then you did not remove all the affected laminate. Determining how much laminate to peel is done using a patch test and moisture meter, described in the article I posted previously.

There is no scientific basis for pressure washing removing moisture, glycol, or acid from laminate. Moisture meters are designed to register water, not glycol or acetic acid, so there's no way to know if those remain if moisture levels drop once laminate is exposed. If the bottom is peeled back to dry laminate, then there is no possibility for acetic acid or glycol to exist or be created as the osmosis process cannot occur without moisture.

I have undertaken many osmosis repair jobs that are the result of failed previous repairs, done by other yards, because all the affected laminate was not removed. Having said that, in most of those cases the previous repair involved removal of just the gelcoat alone, tenting, drying, pressure washing, spot grinding and repairing blisters, barrier coating etc. and no removal of any laminate, so you might get away with your approach provided your new laminate is thick enough, but once again if you are seeing moisture levels drop, then you are leaving behind affected laminate.

I have on a few occasions undertaken repairs on vessels wherein moisture penetration was so deep I could not practically remove enough laminate. In those cases I told the owners I could not offer our usual 10 year warranty for the repair, however, those always involved four or mare laminates, making it very difficult for a blister to ever reappear. The blisters on some of those vessel were softball-sized. I never had a come-back on any blister repair I undertook, even the ones where I could not remove sufficient laminate to offer the warranty, but again they always involved four or more laminates. In order to protect my reputation as a respected blister repair facility, no matter how many times a customer asked, I never undertook the cosmetic approach, individual blister grinding, fairing, and barrier coating.

Thickening epoxy in the field to make your own fairing compound usually makes for difficult sanding. Awlfair, as Jedi noted, is far easier to use. If you've tested it, OK but I'd try Awlfair or a similar, light filler for a comparison.

Attached are photos of the patch laminate test, and some of those very large blisters after peeling, where no more laminate could be removed.

Did I mention you can't dry wet laminate?
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Old Today, 07:01   #39
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Re: Does my hull still need a barrier coat

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Originally Posted by Steve DAntonio View Post
Just to be clear, if you "noticed a significant drop in moisture readings after several pressure washes" then you did not remove all the affected laminate. Determining how much laminate to peel is done using a patch test and moisture meter, described in the article I posted previously.

There is no scientific basis for pressure washing removing moisture, glycol, or acid from laminate. Moisture meters are designed to register water, not glycol or acetic acid, so there's no way to know if those remain if moisture levels drop once laminate is exposed. If the bottom is peeled back to dry laminate, then there is no possibility for acetic acid or glycol to exist or be created as the osmosis process cannot occur without moisture.

I have undertaken many osmosis repair jobs that are the result of failed previous repairs, done by other yards, because all the affected laminate was not removed. Having said that, in most of those cases the previous repair involved removal of just the gelcoat alone, tenting, drying, pressure washing, spot grinding and repairing blisters, barrier coating etc. and no removal of any laminate, so you might get away with your approach provided your new laminate is thick enough, but once again if you are seeing moisture levels drop, then you are leaving behind affected laminate.

I have on a few occasions undertaken repairs on vessels wherein moisture penetration was so deep I could not practically remove enough laminate. In those cases I told the owners I could not offer our usual 10 year warranty for the repair, however, those always involved four or mare laminates, making it very difficult for a blister to ever reappear. The blisters on some of those vessel were softball-sized. I never had a come-back on any blister repair I undertook, even the ones where I could not remove sufficient laminate to offer the warranty, but again they always involved four or more laminates. In order to protect my reputation as a respected blister repair facility, no matter how many times a customer asked, I never undertook the cosmetic approach, individual blister grinding, fairing, and barrier coating.

Thickening epoxy in the field to make your own fairing compound usually makes for difficult sanding. Awlfair, as Jedi noted, is far easier to use. If you've tested it, OK but I'd try Awlfair or a similar, light filler for a comparison.

Attached are photos of the patch laminate test, and some of those very large blisters after peeling, where no more laminate could be removed.

Did I mention you can't dry wet laminate?
So Steve, that last picture is exactly what I was talking about: the csm has been peeled away but there are some pockets of it still left and this is where the blister in your picture is. The pocket goes further up and at the blister you see evidence of the void in the csm.
Did you just forego warranty and slapped filler on there or did you grind that pocket out and fill/patch/fair it before adding the first layer of glass to the hull? This is where spot fix before glassing is better for diy but for a commercial service it may be too costly in man hours of-course.
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Old Today, 11:29   #40
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Re: Does my hull still need a barrier coat

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Hahaha we got the same story

Here’s another product... it says no need to sand but you do
https://www.jamestowndistributors.co...t.do?pid=97453
Hows it treat the trailer?
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Old Today, 16:34   #41
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Re: Does my hull still need a barrier coat

Quote:
Originally Posted by Steve DAntonio View Post
Just to be clear, if you "noticed a significant drop in moisture readings after several pressure washes" then you did not remove all the affected laminate. Determining how much laminate to peel is done using a patch test and moisture meter, described in the article I posted previously.

There is no scientific basis for pressure washing removing moisture, glycol, or acid from laminate. Moisture meters are designed to register water, not glycol or acetic acid, so there's no way to know if those remain if moisture levels drop once laminate is exposed. If the bottom is peeled back to dry laminate, then there is no possibility for acetic acid or glycol to exist or be created as the osmosis process cannot occur without moisture.

I have undertaken many osmosis repair jobs that are the result of failed previous repairs, done by other yards, because all the affected laminate was not removed. Having said that, in most of those cases the previous repair involved removal of just the gelcoat alone, tenting, drying, pressure washing, spot grinding and repairing blisters, barrier coating etc. and no removal of any laminate, so you might get away with your approach provided your new laminate is thick enough, but once again if you are seeing moisture levels drop, then you are leaving behind affected laminate.

I have on a few occasions undertaken repairs on vessels wherein moisture penetration was so deep I could not practically remove enough laminate. In those cases I told the owners I could not offer our usual 10 year warranty for the repair, however, those always involved four or mare laminates, making it very difficult for a blister to ever reappear. The blisters on some of those vessel were softball-sized. I never had a come-back on any blister repair I undertook, even the ones where I could not remove sufficient laminate to offer the warranty, but again they always involved four or more laminates. In order to protect my reputation as a respected blister repair facility, no matter how many times a customer asked, I never undertook the cosmetic approach, individual blister grinding, fairing, and barrier coating.

Thickening epoxy in the field to make your own fairing compound usually makes for difficult sanding. Awlfair, as Jedi noted, is far easier to use. If you've tested it, OK but I'd try Awlfair or a similar, light filler for a comparison.

Attached are photos of the patch laminate test, and some of those very large blisters after peeling, where no more laminate could be removed.

Did I mention you can't dry wet laminate?

Thanks again for your advice and interest in my project.

This is a link to a post on my facebook page I did way back when this project first started. The pictures show the progression of what I was working with. Maybe they will tell a different story to you than to me. I have learned a lot more about osmosis since I posted this so please don't beat me up too bad for my write up.

https://www.facebook.com/SVWindRiver...979?__tn__=K-R

I can't remember if the "significant drop" in moisture meter readings were after the first peel or the second. I did pressure washing on both. For grins I am going to tape some plastic on my hull today and see what happens.

My blister problem was mild compared to many I have read about. One thing I learned from your article is about the resin corrosion that can be mistaken for a dry layup. I think I experienced this on my boat. The resin in these area just seemed different than others and dry was the only was I knew to describe it. Looking back now it seem like these area were "crystalized". The reason I considered it a dry lay up is that I found similar resin/glass mixtures on the deck fiberglass when I replaced them.

This picture is of a small area of CSM that I was able to slide a chisel underneath and peel it off. I considered this dry but it may be resin corrosion. I have gone over most of the hull where there is still CSM showing and scraped these areas with a chisel. If I was able to get under and lift the CSM, I removed that area with a grinder.

I actually started a third peel on my hull to get rid of the last bits of CSM but it seemed that even with that peel I still uncovered more CSM and I was starting to also remove roving but the glass didn't seem to be changing. The first layers of CSM I removed with the peeler were obviously different than what I see now. They even smelled different when peeling or grinding them. I stopped the third peel after a few square yards. I feel pretty confident that I have a good base to build on. It may not be absolutely perfect but I think I have done a good job up to this point and far more than most DIYer's would care to do. My boat has to be back on it's mooring by the end of this year and I still have a lot of projects yet to do. Onward!

With your permission, I would like to link to your article on my facebook page. I think there are many who would benefit from it that may miss this thread.
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