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Thread: Exterior Sheathing - Peel Ply left uncovered spots on tape

  1. #1
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    Default Exterior Sheathing - Peel Ply left uncovered spots on tape

    I just removed the peel ply from some fiberglass taping of the exterior seams of boat.

    My next move is to lay down fiberglass cloth to sheath the entire thing.

    I noticed that there are many spots on the fiberglass tape that have divots (not sure what to call them).

    Anything I should do about this prior to laying the fiberglass cloth?

    20210223_110016 (1).jpg

  2. #2
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    yeah, divots/bubbles same difference. Those were bubbles under the peel ply and you can see the wrinkles that were in the peel ply too. For some reason people recently have been using peel ply for non-vacuum bag layups, which I suppose doesn't hurt anything and possibly eliminates sanding but primarily the stuff is for use under a layer of bleeder cloth (in order: wetted out glass/peel ply squeegeed on/bleeder cloth/bleeder hose/vacuum bag).The bleeder cloth is a fluffy polyester layer which lets the excess resin suck up into itself under vacuum, meanwhile the vacuum pressure eliminates dry spots like that. So, basically just squeegee some resin into those spots and sand them flat when it's kicked

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Sand down the high spots without going so deep as to scar the wood. Fill with putty or thickened epoxy. Sand smooth. Glass.

    Any bump or hollow will transmit through the cloth and be a blemish on your nice paint job.
    Hope for the best, but plan for the worst.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Thank you for the replies.

    I'll sand down smooth the fiberglass tape so there are no ridges or bumps.
    Fill in any spots with thickened epoxy.

    Sound good?

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Unlike the surrounding areas, the depressions are not free of amine blush. A small brush and some water can fix that. A Nyalox brush in a drill works as well and will give you a good surface for adhesion. You can fill with unthickened resin and more peel ply or fill with partially gelled epoxy or thickened epoxy that can be easily sanded. You need a smooth surface before sheathing or you won’t be happy with the results.
    Last edited by cyclone; 02-23-2021 at 06:08 PM.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Thanks for the information.

    You all and the others on this site are very helpful indeed.
    I wouldn't have gotten this far without the assistance.

  7. #7
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Lightly hand-sand any sharp high spots off with 100 grit then rub the area with a Scotchbright pad and water, which is sufficient prepping before glassing.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Are you saying to do this instead of filling in with epoxy or is this after I finish with filling in the divots?

    I had planned on using 80 grit orbital sander. That too much and may cut into glass?



    Quote Originally Posted by Lugalong View Post
    Lightly hand-sand any sharp high spots off with 100 grit then rub the area with a Scotchbright pad and water, which is sufficient prepping before glassing.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Unless there are a mighty big number of these blemishes, I wouldn't resort to power tools - hand sanding would be fine. You just want to knock the high spots down. I would recommend filling with fairing compound and sanding to fair before glassing, but as I have said many times here, there are a dozen solutions to any problem, and two or three are probably correct. For myself (and any build project that I am in charge of), I would prefer to have the substrate surface as fair and perfect as possible before exterior 'glassing, but that is not the only way to achieve that same end.
    Hope for the best, but plan for the worst.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Lightly hand-sand any sharp high spots off with 100 grit then rub the area with a Scotchbright pad and water, which is sufficient prepping before glassing.
    This approach is actually backwards. The plan should always be to remove the blush with the Scotchbrite and water first, then do any needed sanding. Otherwise, you are just smearing blush down into the freshly sanded surface.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Scrub off the amine from all surfaces. Use a sanding block to remove the high spots. Fill with thickened. Scrub off the new amine. Sand everything with 100. Apply glass. This is the one and only way to do it right.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    I'd try a cabinet scraper before resorting to sand paper. IMO it's always better to cut rather than sand if you can.
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    I'm another who hasn't absorbed the benefits of using peel ply outside of the vacuum bagging process; however I remain to be convinced.

    I try to flatten those lumps along the tape edge with a paint scraper, which also works to tear out areas of dry cloth as per your pic, at the green epoxy stage . I'm a WEST system guy so 407 would be my filler of choice, mayo consistency. I like to fill and fair seams as I build up the layers but I use 6oz cloth exclusively so you materials might warrant a different approach.

    Can we a pic of the overall project, for scope. Good luck with it! / Jim

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    I often use peel ply in simple wet layups, even if not bagging, It reduces/eliminates fill coats, helps tame wrinkled glass and leaves a surface that needs less work.

    Not a big problem. The next lamination can fill it in.
    Swipe it with a wet rag to remove any blush.
    Sand any rim of the craters flush. Use a block.
    If craters are small and only one layer, don’t fill ‘em, as the next lamination, if you supply enough resin to fill the divots will probably lie flat, especially if you use peel ply..
    Last edited by JimConlin; 02-23-2021 at 08:07 PM.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    All great, thank you.

    I'm building an ozarkian, like a jon boat.

    I sanded the taping which helped tremendously by reducing bumps and smoothing things out.

    It's hard to get the little craters on the edges without sanding too much of the wood.

    Now I left with the little craters that are not deep, hopefully you can tell by pics below.

    There are too many areas to patch, probably would be better to just put a coating of epoxy on all taped seams.

    I'd like to avoid that if possible and go directly to laying the cloth but do want it to look nice after being painted.

    I'm going with 10oz cloth and plan on putting 5 or so coats of epoxy on, more if needed to fill the weaves.

    Should I fill them in with epoxy and sand smooth then lay cloth or just lay the cloth?

    20210223_192520.jpg

    20210223_192456.jpg

    20210223_192438.jpg

    20210223_193057.jpg

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    I would use a 6" drywall taping knife and do them all. It won't be much extra work. The trouble with craters and even pin holes is that the covering material will often just bridge them and the resin will run out, especially on the vertical surfaces, and you'll have voids forever. If they get filled with water you may have problems later. It's better to just fill them, especially when it's so easy.

    You can fill with material thickened enough not to sag then glass over immediately and avoid any more sanding.

    Looks like the catfish are in trouble.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    I like that idea of the taping knife and the thickened epoxy.
    Thanks.





    Quote Originally Posted by Gib Etheridge View Post
    I would use a 6" drywall taping knife and do them all. It won't be much extra work. The trouble with craters and even pin holes is that the covering material will often just bridge them and the resin will run out, especially on the vertical surfaces, and you'll have voids forever. If they get filled with water you may have problems later. It's better to just fill them, especially when it's so easy.

    You can fill with material thickened enough not to sag then glass over immediately and avoid any more sanding.

    Looks like the catfish are in trouble.

  18. #18
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    The 6” drywall knife is my first tool in this work. If you plan to do any amount of it, get a hawk also. It’s much cleaner and quicker when you get a feel for it. Fill holes as you go along, for sure. / Jim

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Despite the fact that we always seem to have some very smart and competent builders building some really nice boats here, I will remind you all again that doing any sort of serious sanding on epoxy resin which has yet to fully cure (takes a week or better) is a pretty serious health risk. If you happen to get sensitized, you're screwed. Carry on, but keep that in mind.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Quote Originally Posted by toclimbk2 View Post
    Are you saying to do this instead of filling in with epoxy or is this after I finish with filling in the divots?

    I had planned on using 80 grit orbital sander. That too much and may cut into glass?
    Removing more material than necessary creates more dust and greater health risk. Minimal hand sanding is next best to scraping or shaving with a very sharp blade. Included here is a pic of blaes made from broken industrial hacksaw blades. One side is ground hollow and the other has a rounded bevel. These have lasted for 20+ years and are still going strong....IMO pretty much indispensable for resin/glass work.Washing trim knives WBF.jpg

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Quote Originally Posted by Todd Bradshaw View Post
    This approach is actually backwards. The plan should always be to remove the blush with the Scotchbrite and water first, then do any needed sanding. Otherwise, you are just smearing blush down into the freshly sanded surface.
    The object is to use only a small quantity of water rather than trying to flush the amine away with flowing water. Prior sanding/scraping or scratching has prepped the surface for bonding, so Scotchbright can get into the bubble recess. Sure, washing first is prefferable from the health viewpoint and is probably worth the extra waiting time that is needed till the job is dry enough to start glassing. Not a bad idea to scim-over repair areas with slightly thickened fill resin (thickened with Cabosil) before laying the cloth.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    The object is to use only a small quantity of water rather than trying to flush the amine away with flowing water.
    Actually, the object is to use however much water it takes to be able to get the amine off of the surface, rather than just get it wet and smear it around.

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Quote Originally Posted by Todd Bradshaw View Post
    Despite the fact that we always seem to have some very smart and competent builders building some really nice boats here, I will remind you all again that doing any sort of serious sanding on epoxy resin which has yet to fully cure (takes a week or better) is a pretty serious health risk. If you happen to get sensitized, you're screwed. Carry on, but keep that in mind.

    Please, please, PLEASE listen to Todd.

    Please.

    Peace,
    Itchy Bumperton

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Quote Originally Posted by Todd Bradshaw View Post
    Actually, the object is to use however much water it takes to be able to get the amine off of the surface, rather than just get it wet and smear it around.
    No "smearing it around", Once the immediate repair area has been scraped, scratched, sanded or shaved, whatever, final rubbing or two with a little water will leave neary a trace of amine. Go the other extreme if you wish and slosh away with water first.

  25. #25
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Quote Originally Posted by toclimbk2 View Post
    All great, thank you.

    I'm building an ozarkian, like a jon boat.

    I sanded the taping which helped tremendously by reducing bumps and smoothing things out.

    It's hard to get the little craters on the edges without sanding too much of the wood.

    Now I left with the little craters that are not deep, hopefully you can tell by pics below.

    There are too many areas to patch, probably would be better to just put a coating of epoxy on all taped seams.

    I'd like to avoid that if possible and go directly to laying the cloth but do want it to look nice after being painted.

    I'm going with 10oz cloth and plan on putting 5 or so coats of epoxy on, more if needed to fill the weaves.

    Should I fill them in with epoxy and sand smooth then lay cloth or just lay the cloth?

    20210223_192520.jpg

    20210223_192456.jpg

    20210223_192438.jpg

    20210223_193057.jpg
    If you use ` knife , like I showed in a few post's after this one, you will be able to dig into and scratch to the bottom of even those small spots showed in your pics. Finally or firstly wiping and scrubbing with a scrub pad does the prep trick, but do remember to then dry the surface well. lastly, a fine putty knife can be used to squeeze thickened resin into the rough spots immediately before adding another epoxy coating (with or without glass fabric).....And by the way, DO PLEASE listen to Todd and start off by washing down with water before you start with any power sanding. Small touch-up areas that need attention before additional coating after this, do not then need a repeat of the 'first wash' process.
    Last edited by Lugalong; 02-24-2021 at 12:38 PM.

  26. #26
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    "I will remind you all again that doing any sort of serious sanding on epoxy resin which has yet to fully cure (takes a week or better) is a pretty serious health risk."

    For those who are new to epoxy work this bears repeating. Power sanding should not be conducted without strict adherence to safety considerations. I try to avoid the need for it until the final fairing stages wherever possible, and preferably on cured epoxy. Working clean with sharp tools goes a long way toward that goal. All the best with it. / Jim

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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    I think I'll continue to "slosh away" as it were. In 45 years of working with epoxy resin, first in college and then on boats and similar stuff, careful water washing has always worked beautifully.

    Gougeon Brothers:

    Amine blush may appear as a wax-like film on cured epoxy surfaces. It is a by-product of the curing process and may be more noticeable in cool, moist conditions. Amine blush can clog sandpaper and inhibit subsequent bonding, but this inert substance can easily be removed. To remove the blush, wash the surface with clean water (not solvent) and an abrasive pad, such as Scotch-brite(TM) 7447 General Purpose Hand Pads. Dry the surface with paper towels to remove the dissolved blush before it dries on the surface.

    Blush tends to clog sandpaper. Cured epoxy coatings sand much better after they have been washed with water.

    Jamestown Distributors in their Total Boat Epoxy instructions:

    Amine blush appears as a waxy coating on the surface of cured epoxy. Sanding does not remove amine blush, it just pushes it around on the surface. Use a Scotch-Brite abrasive pad and water (not solvent) to remove amine blush; change the water regularly to ensure all blush byproduct is removed completely. Rinse surface thoroughly, and allow the surface to dry.
    International Yachtpaint:

    Amine blush is water soluble, making it easy to remove. We recommend thoroughly washing the cured epoxy with clean warm water, all-purpose soap, and a stiff brush. Clean the amine blush off the epoxy before sanding as well. It is a safe practice to clean all types of epoxy resin, even if the label states that it is ‘amine blush free’ or ‘no blush formula.
    Interlux:

    You will want to clean the amine blush off of the epoxy before sanding. If you begin to sand before removing the amine blush, you may sand the blush deeper into the surface making it much harder to remove.
    Dur-A-Flex (manufacturing epoxy resin flooring coatings)

    How to Properly Remove an Amine Blush?

    Because of the ionic nature of amine blush, the use of solvents to remove a blush is not very effective. However, the use of Dawn® dish soap in hot water following the Dur-A-Flex Cleaning Guidelines works well to remove and suspend the amine blush from the epoxy surface. Depending on the cleaning equipment available, it is recommended to repeat the cleaning process once or twice, prior to rinsing thoroughly with hot water, allowing the surface to dry before visual inspection and retest for amine blush. Never use mechanical means alone to sand an amine blush off as this may result in spreading this bond breaker around.
    Personally, I have never had a reason to add any soap to the water. I don't think it is worth the contamination risk and I haven't seen any evidence that plain water needs anything else on my boatbuilding projects. Back in the early days, Gougeon Brothers suggested that a bit of ammonia could be added, but they later went back to plain water.

  28. #28
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    Default Re: Exterior Sheathing - Peel Ply left uncovered spots on tape

    Now I'm scared as I just took off and started sanding without wiping it down with water first.

    Well I know now for future sanding of epoxy.

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