Stripping 20 Year Old Awlgrip

[phorvati]

I just tried soy strip on my stern. I followed directions, and after applying a generous coat, I covered the area with plastic sheet to keep it moist and allow stripper to work. Its been 4 hours and I didnt see any results yet. One problem might be that temperature has been in the 40s. The label says for best results use in 50F or above. Im going to wait another day and see what happens. But my gut instinct tells me this stuff is not very effective.

Has anyone managed to chemically remove topside alwgrip with any success? what kind of stripper would work?

[Pelagic]

Are you asking about stripping Paint or Varnished wood?
If Painted Topsides in Awlgrip, why not sand down to a good layer of substrate?

[minaret]

Originally Posted by phorvati

I just tried soy strip on my stern. I followed directions, and after applying a generous coat, I covered the area with plastic sheet to keep it moist and allow stripper to work. Its been 4 hours and I didnt see any results yet. One problem might be that temperature has been in the 40s. The label says for best results use in 50F or above. Im going to wait another day and see what happens. But my gut instinct tells me this stuff is not very effective.

Has anyone managed to chemically remove topside alwgrip with any success? what kind of stripper would work?

Aircraft stripper works great. Soy strip is pretty useless for this. Here's what I use-

Klean-Strip®


That said, I only chemical strip on very convoluted shapes, generally a mast or boom, that are difficult to sand. Awlgrip is so thin that it sands right off with not much more effort than the sanding you will need to do for prep. In fact I find that sometimes if you chemical strip the topcoat, you may have a hard time sanding the primer underneath for prep without blowing through. You also risk chemical contamination of the surface, and all that exposure to some extremely nasty chems. Just 220 DA it off, then it's ready for primer as soon as you're done. If it's a color that required a lot of coats for coverage, you can step back to 180 until it's almost gone, then finish with 220. In some cases you can even sand off the topcoat with 320/400 and re topcoat without new primer. I'd never chemical strip Awlgrip off of a hull. So much mess and work, when sanding can be done so much faster, and with dust extraction is much cleaner and easier, and must be done for prep anyway.

[phorvati]

Thanks minaret,
I'm definitely getting it before thanksgiving. I get 4 days off to do something about this hull. I am hoping I can get rid of flag blue awlgrip and grey primer, and wet-sand/buff the red gelcoat without painting it again. Its a lot of work but I would preserve the original gelcoat surface and its smoothness.
Was Klean strip to remove awl-grip on topsides?

My topsides are so bad, stuff is just cracking and flaking off, grey primer too. Its begging to come off and in spots where it came off, it looks like a healthy original red gelcoat. Fairing those peeled spots is hard to have come out smooth when you have a large surface.
I would prefer to remove everything, including the primer, and asses the red gelcoat first. Don't want to damage the gelcoat as a result of using force to remove awlgrip and primer, or create uneven surface that becomes obvious only after new flag blue awlgrip is applied.

If i do end up needing to paint the hull it would be in the spring. Likely with all the rains and weathering, i think chemicals would be gone 6 months later.

[minaret]

Originally Posted by phorvati

Thanks minaret,
I'm definitely getting it before thanksgiving. I get 4 days off to do something about this hull. I am hoping I can get rid of flag blue awlgrip and grey primer, and wet-sand/buff the red gelcoat without painting it again. Its a lot of work but I would preserve the original gelcoat surface and its smoothness.
Was Klean strip to remove awl-grip on topsides?

My topsides are so bad, stuff is just cracking and flaking off, grey primer too. Its begging to come off and in spots where it came off, it looks like a healthy original red gelcoat. Fairing those peeled spots is hard to have come out smooth when you have a large surface.
I would prefer to remove everything, including the primer, and asses the red gelcoat first. Don't want to damage the gelcoat as a result of using force to remove awlgrip and primer, or create uneven surface that becomes obvious only after new flag blue awlgrip is applied.

If i do end up needing to paint the hull it would be in the spring. Likely with all the rains and weathering, i think chemicals would be gone 6 months later.

Interesting, sounds like there may have been a poor prep job before painting, Awlgrip should never flake. It's possible that what you are trying to do may work out, but here are some things to consider. The PO painted it for a reason-perhaps several reasons. I would not be surprised if you find a repair (or repairs) in the topsides. I would also not be surprised if the red gelcoat is heavily oxidized. Red is a difficult color to work with for many reasons. It is the hardest of all colors to color match. It oxidizes quickly. I would guess the PO was not happy with the original red gelcoat for some reason or reasons, and you will probably find out what that was when you strip it. Klean-strip will remove Awlgrip, but I never use it on painted gelcoat, only aluminum surfaces like a mast. I'm not sure what it would do to the gel. Very likely any stripper that will remove Awlgrip will also at least dull the gel and make it harder to bring back to a finish. I would still be looking at sanding it off. The gel should be thick enough to give you some wiggle room, I'd 180 the paint off till almost gone, then work up to 800 film discs and polish it. Guide coat between grits for an even finish.

[phorvati]

So if I understand you, use 180 grit pads with random orbit sander until flag blue and grey primer is almost gone.
"then work up to 800 film discs and polish it." Work up from 180, I take it that would be 220, 400, 600 then 800 grit? Would you do this dry or wet? with sander or by hand?
"Guide coat between grits for an even finish" Paint something in between? So going from for instance 180 to 220, i would apply a coat of something?

[sailr69]

Originally Posted by minaret

Interesting, sounds like there may have been a poor prep job before painting, Awlgrip should never flake. It's possible that what you are trying to do may work out, but here are some things to consider. The PO painted it for a reason-perhaps several reasons. I would not be surprised if you find a repair (or repairs) in the topsides. I would also not be surprised if the red gelcoat is heavily oxidized. Red is a difficult color to work with for many reasons. It is the hardest of all colors to color match. It oxidizes quickly. I would guess the PO was not happy with the original red gelcoat for some reason or reasons, and you will probably find out what that was when you strip it. Klean-strip will remove Awlgrip, but I never use it on painted gelcoat, only aluminum surfaces like a mast. I'm not sure what it would do to the gel. Very likely any stripper that will remove Awlgrip will also at least dull the gel and make it harder to bring back to a finish. I would still be looking at sanding it off. The gel should be thick enough to give you some wiggle room, I'd 180 the paint off till almost gone, then work up to 800 film discs and polish it. Guide coat between grits for an even finish.

never use a stripper with methaline chloride. on fiberglas

[minaret]

Originally Posted by phorvati

So if I understand you, use 180 grit pads with random orbit sander until flag blue and grey primer is almost gone.
"then work up to 800 film discs and polish it." Work up from 180, I take it that would be 220, 400, 600 then 800 grit? Would you do this dry or wet? with sander or by hand?
"Guide coat between grits for an even finish" Paint something in between? So going from for instance 180 to 220, i would apply a coat of something?

Sure, though I'd probably do 320 as well. As you can see it's a lot of grits to work through, which is why you want to start going up while theres still a hair bit of primer left. Guide coat is a spray on chalk like paint that comes in cans, often blaze orange but you can get any color. It is a basic painters technique used in numerous industries. You just quickly overspray the whole surface with it between grits so you can see where you've sanded and where you haven't; this allows you to do a large surface without missing any spots at all. It will also highlight all lows and imperfections for you, and you save time by doing most of the sanding by machine and minimizing hand sanding. It prevents you from sanding too much or too little as well, since you can see individual grit scratches, peel, and imperfections with a good system. We often use a wipe on dye system but thats only for paint prep. One of the advantages of regular guide coat is it wipes right off clean with a little alchohol. I would sand dry film discs on a DA all the way up to 800. For the hand sanding from 400-800 you can wet sand with a foamy block.

[phorvati]

So stripper will not work. It lifted the paint, but it made gelcoat pretty brittle on the patch i did on the stern. In spots where I left it overnight, it literally disintegrated the gelcoat, leaving Swiss cheese like holes. It was cracking and coming off in crumbs all the way to glass. So it looks like I'll be sanding after all, and fairing...

I tried few sanding disks on the stern. 180 was clogging up immediately, and so was any grit down to 100. 80 looks like it was working but it would take a lifetime to do. That left me with 60 grit. That worked pretty good taking off the paint. I am looking at about 2 sq-ft per hour of sanding time to get to the grey primer. My aim would be to leave the primer where possible. Hull is pretty uneven, as I was trying to get blue awlgrip removed, some divots were pretty deep and i ended up sanding through the gelcoat as well. this was the stern, hopefully sides will be better.
It will be a long thanksgiving weekend, and a long winter.

BTW. thanks for the pics and guide coat clarification. Yeah, I'll be getting that as well. along with the fairing board, and fairing filler.

[minaret]

Originally Posted by phorvati

So stripper will not work. It lifted the paint, but it made gelcoat pretty brittle on the patch i did on the stern. In spots where I left it overnight, it literally disintegrated the gelcoat, leaving Swiss cheese like holes. It was cracking and coming off in crumbs all the way to glass. So it looks like I'll be sanding after all, and fairing...

I tried few sanding disks on the stern. 180 was clogging up immediately, and so was any grit down to 100. 80 looks like it was working but it would take a lifetime to do. That left me with 60 grit. That worked pretty good taking off the paint. I am looking at about 2 sq-ft per hour of sanding time to get to the grey primer. My aim would be to leave the primer where possible. Hull is pretty uneven, as I was trying to get blue awlgrip removed, some divots were pretty deep and i ended up sanding through the gelcoat as well. this was the stern, hopefully sides will be better.
It will be a long thanksgiving weekend, and a long winter.

BTW. thanks for the pics and guide coat clarification. Yeah, I'll be getting that as well. along with the fairing board, and fairing filler.

Wow that must be thick paint. What sort of tool are you sanding with? Have you tried Abranet mesh discs? Mirka Abranet Mesh Abrasive 5" Dust Free Sanding Disk Assortment Pack (35 Count) - Amazon.com
These clog a lot less, particularly if used as designed with vacuum extraction. If you sand the whole thing out with 60, you will definitely be doing fairing and/or high build primer, as well as prime and paint. It sounds like you are well aware of this and already committed to the process, it might be the best thing in the end. Sorry to hear you melted some gelcoat, but it's not surprising if you left aircraft stripper on it overnight. Keep at it and good luck!

[CharlieCobra]

This is an indoor job. I learned many years ago to be very careful with strippers on glass. I would've used Peel-Away, left on 24 hours with some heat to pop the Alwgrip. It won't touch an epoxy primer though. You would have to manually scrape the residue off and nuetralize before sanding or you would eat sanding disc like mad. We usually throw a ton of bodies at it with DA's for prep. Hence one of the reasons why repaints are as pricey as they are. There ain't no easy way to do it.

[Roy M]

This applies to epoxy-based boats, much less to polyester boats (though, with care and working in small units, it will apply to gelcoat-based, LPU-covered boats). My Searunner is approaching thirty-five years afloat. I've had the opportunity, several times, to strip old LPU (linear polyurethane paint) from the epoxy/glass substrate over plywood. For removing the LPU and sand nonskid, I have tried everything, including a heat gun. The all-time best agent, considering that time is money and this job is BORING, is to use a methylene chloride based commercial paint/epoxy stripper. Work in small areas, a couple square feet at a time, brush on the jelly-like goop and spread it around. Work in the shade where possible, as you want it to do its magic right the first time without having to reapply. It will bubble up, then, with a wide blade paint scraper, scoop up the ugly mess and deposit it in a waste container. Keep doing this for all the non-skid areas, section by section. If it will take place over a several day period, you don't have to do anything to the substrate. If you are doing it over successive days, let the stripped section dry, sand it with 60 grit paper, repair any bad sections of glass or epoxy, then give it a coat of epoxy primer. Mark Johnson, of the Searunner thread, suggests a grey primer to make it even more UV-opaque. I haven't tried that yet, but it makes sense, as white pigments transmit white light a short ways into the interior.

For other than nonskid, and assuming the substrate is not exposed, simply treat the old LPU paint as base coat. Sand it well, prime if it needs it, in patches, then apply a couple new coats of LPU. Plastic is plastic. If the old LPU is stable, paint your favorite brand over the existing. Sterling bonds perfectly to well prepared Awlgrip, and VICE-VERSA.

Time is more valuable than money. Don't waste it when you don't need to. Make the boat pretty and seaworthy, and then go out and consume time sailing.

[David M]

Now that you have a bunch of loose soft stuff that is going to clog any abrasive that you use, a pressure washer is the alternative. Dont use the cheap electric home jobs that only have a thousand pounds of pressure or so. Rent a professional grade gas powered washer with at least 3000 pounds of pressure. Since the gelcoat is damaged beyond hope, you need to get down to the hard substrate that is not delaminating that will make a secure foundation for your coatings. If anything is not secure enough, the pressure washer will remove it. You then fill and fair with an epoxy fairing compound (never Bondo as tempting as the price might be), apply the primer and then the finish coat. Interlux Interfill Epoxy Filler works well. It will probably not work in 40 degree temperatures, but then none of your other two part coatings will work either. You may want to wait for Spring for the temperatures to warm up.

BTW, the only stripper that I have found that works well is the Jasco brand. The supposedly environmentaly safe brands are much too weak if not effective at all. That's just been my own experience experimenting with many different strippers over the years. When you think about it, what is safe for the environment that can also strip paint?

[phorvati]

My stripper test patch was only about square foot. And it made gelcoat brittle in couple of small spots. So its hardly any worry. Its on the stern. I gave up on chemicals, and resorted to palm sander 60 grit paper. Got the stern done, and about 1/3 of the way on port side. C&C 38. About 10 total hours. I am feeling my way for divots as I sand, and trying not to press on any one spot too much. Tendency is to try to dig out the islands of blue paint, but Ive learned to stay away from that and keep the sander moving. I guess next step would be to order the flexible long board, apply guide coat, then do 80 grit by hand with a 30" flex board. That would fair out any accidental divots I made with palm sander. I looked at various spots on the hull against the sun today, areas where i haven't sanded yet, and the hull is very fair as it is, so i really only have to worry about divots i make as I'm removing the old paint. I will need a fairing filler but i am hoping it will be only i few obvious spots.

[minaret]

Originally Posted by phorvati

and resorted to palm sander 60 grit paper.

There's your problem. A palm sander will be very slow and will clog heavily. Use a quality 5" random orbit disc sander. Something with some horsepower. I like Porter Cable, Fein, or Festool for electric DA sanders. Pneumatic is always better but you need an industrial sized compressor to run them.



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