Getting fed up with MAS epoxy

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Getting fed up with MAS epoxy

Postby DanaDCole on Sat Sep 12, 2015 11:27 am

Don't get me wrong, I love MAS for the lack of fumes, no blush, and ease of use, but trying to get a smooth surface on bright-finished areas that are not 'glassed is a real nightmare. I am getting sick and tired of applying epoxy, sanding through it in spots, applying epoxy again--repeat, repeat, repeat. In my previous post, "sanding through epoxy," a responder mentioned that he had talked to a "tech rep" at CLC and the tech mentioned that the one thing he did not like about MAS epoxy is that it "cures a little lumpy." No kidding?! I'd say it cures a lot lumpy. The tech rep also mentioned that using a hair dryer after applying the epoxy seemed to help. Maybe I didn't do it right, but if anything this idea made things worse. He also said not to sand as much, but that would still leave my bright-finished areas embarrassingly "lumpy." We've had a cool spell and I had hoped that being able to apply the epoxy this morning at 70 degrees would help, but that was not to be.

This does not seem to be much of a problem when there is fiberglass under the epoxy. I did sand through in two or thee spots on the hull and had to patch them, but that's about it. I don't know why the problem is so much worse on un-'glassed areas, but even when I have put on four coats before any sanding it just goes right through to wood in spots, even with 220 paper (by hand, no power sander). I'm very sure I have not damaged the fiberglass on the 'glassed areas--I hope I am right. I had thought of going ahead and varnishing the mahogany parts, e.g., rub rails, toe rails, and a few others, hoping that would seal it enough, but after reading the horror stories here: http://www.clcboats.com/life-of-boats-blog/what-happens-when-stitch-and-glue-boats-age.html, I have decided that was a bad idea.

So what to do? I'm considering purchasing a quart of West System with their 207 hardener. This is the brand Russell Brown recommends, and I think Jeff Kerr prefers it also. Or would System Three be better? Anyone who has experience with either or both these brands, please let me know what you think before I blow a wad of money on either one.
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Re: Getting fed up with MAS epoxy

Postby Bflat on Sat Sep 12, 2015 3:31 pm

A penetrating epoxy might be the answer. CPES is one type and is the one most commonly mentioned but there are many others and each epoxy maker seems to carry one. On Youtube, "Tips from a shipwright" has a demo of its use. One of its main uses is for under varnish.

On the other hand there is a school of thought that epoxy under varnish isn't such a great idea in that it makes it more difficult when one eventually needs to do a complete refinish, sanding down to bare wood. The epoxy supposedly makes that harder to do. This seems to be a minority opinion with the majority saying that having epoxy as a base coat makes varnish last longer.

I have no personal experience with this stuff, but I'm inclined to skip the epoxy and go right to varnish on my bright work. I don't plan to epoxy coat my tiller, spars, rub rails, toe rails, and any other varnished trim. Lots of varnish methods recommend thinning the first coat of varnish to get good penetration. It would seem that epoxy wouldn't allow that method to work.

One thing I have noticed is that when it comes to varnish there seems to be no consensus as to the best method or brand. That usually indicates that no option is without problems (choose your poison). If there was one best answer we'd know it by now. There are, however strongly held opinions. I'm still trying to decide just what to do.

Some people avoid it altogether and use paint. Have you noticed that Geoff Kerr's Caledonia Yawl has painted spars? They look great. Others say that spars should never be painted for the same reason that a wooden ladder is never be painted.

I've considered varnishing with the option of covering it with paint if the upkeep ever gets to be too much.
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Re: Getting fed up with MAS epoxy

Postby DanaDCole on Sat Sep 12, 2015 7:41 pm

You make some very interesting points. I have read, though, that because varnish is porous the wood under it gets damp and expands, then contracts as it dries out. This causes the varnish to crack and fail, so that if the boat lives outside you have to re-varnish every year. If there is epoxy under the varnish you won't have to re-varnish nearly as often--usually only when it gets to be too scarred up. (All the above applies to paint also.) Also, when paint and varnish begin to crack and blister, they hold more moisture in and you start to get rot. Take a look at the stories on the CLC website I referred to earlier: http://www.clcboats.com/life-of-boats-blog/what-happens-when-stitch-and-glue-boats-age.html

All that being said, there is an argument for not painting or varnishing wood at all as long as any unpainted (or unvarnished) areas are above the water line and can drain completely after a rain. An old-time lumberman told me once that as long as unfinished wood can drain properly it only loses about 1/4" every 100 years. So it sounds kind of tempting not to finish the spars or the mast, etc., as long as you are careful that sails, lines, and so on are not attached and holding water onto them. I have already epoxied all the rails and so on that are attached to the boat and plan to varnish them (the mahogany is too pretty to paint). I'm not exactly clear why you say to paint rather than varnish. Is it your opinion that paint seals better than varnish? If so, I'll be glad to hear about it because I have one or two small areas that are covered by paint only (the epoxy was sanded through). They are very small spots and well-drained so I am not too worried.

I am planning to epoxy the spars and mast, etc. However, I'll be keeping the boat under a tarp when I'm not using it in the warm weather and the tabernacle will be removable so I can keep it in the garage in winter. In that case, maybe varnish will be sufficient. However, we may be moving to Wisconsin in a year or so, and I don't know if I'll have a sufficient garage there.

So, thanks for the info on penetrating epoxy. I will definitely look into it.
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Re: Getting fed up with MAS epoxy

Postby craig on Sat Sep 12, 2015 9:12 pm

I've never used mas epoxy, so I can't speak to how lumpy it is in relation to other brands. I know that for my epoxy, it certainly doesn't self level and I have bumps etc to smooth. I'm able to just use my detail sander with 150 grit to get it smooth. Now that I know better, I'll just do enough to get the bumps down but not totally white and chalky, like I used to do. I can't believe you are sanding down to bare wood with 220 grit by hand. I would really think twice about skipping the epoxy, though. Well, I'll put it another way. Your boat, your rules! Haha. For me, after a season of sailing, I'm convinced epoxy is a good idea under all varnish. I think you just won't be able to tell if there are a few bumps or whatever. Maybe post a picture of the epoxy after it cures and before and after sanding so we can see? Maybe people have some experience with "cutting corners" and will know if it's good enough to ignore and just varnish over the epoxy as-is.
Titania, launched January 2015
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Re: Getting fed up with MAS epoxy

Postby DanaDCole on Sat Sep 12, 2015 9:22 pm

I agree totally. I will try getting some pictures, but it may be hard to show the contours. Basically, the epoxy goes on very smooth then begins to flatten out in some areas and rise higher in others in odd patterns. There are a few runs where I got it on too thick, but most of the high and low areas don't appear to have anything to do with gravity, and anyway I get the same patterns on horizontal surfaces. The rises and falls are deep enough that they will definitely show through varnish and look terrible. I might try putting Interlux 1026 sealer on any areas that get sanded through and then go ahead and varnish. Otherwise I will never finish going in circles.
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Re: Getting fed up with MAS epoxy

Postby craig on Sat Sep 12, 2015 9:50 pm

That sounds like fish eyes. Do you have amine blush of surface contamination from oil, or something?



Give the surface a good wash with water and soap on a scotch pag, rinse and dry, then cost with epoxy
Titania, launched January 2015
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Re: Getting fed up with MAS epoxy

Postby DanaDCole on Sat Sep 12, 2015 9:58 pm

No amine blush--using MAS with slow hardener. I always wash down surfaces with denatured alcohol and allow it to dry thoroughly. (Maybe I should try MEK. That stuff scares me though.) I'm sure there is no surface contamination. I will say that it seems to be somewhat worse now than it has been, so something is different but I don't know what. Still, I have always had this problem and have had to do quite a bit of sanding. I know I'm not the only one because of what the tech rep said. He also said not to sand down to a uniform grey with MAS because of the "lumpiness"--sanding down to a uniform grey is what is recommended with West System. I'm about to decide to finish the boat and get it on the water and not care what people think. :)
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Re: Getting fed up with MAS epoxy

Postby Bflat on Sun Sep 13, 2015 12:53 am

I think that with or without epoxy, varnishing once or twice a year is part of the deal with brightwork if it's not protected from sunlight. The only reason I brought up paint is that it's a tempting alternative since it lasts a lot longer than varnish.
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Re: Getting fed up with MAS epoxy

Postby DanaDCole on Sun Sep 13, 2015 8:37 am

I got a shot of some of the epoxy on the toe rail. In order to show the texture, the only light is coming from outside the garage so I had to use a very slow shutter speed (1 1/2 sec) to keep enough of it in focus, even at f11. Image
The epoxy is applied over several previous coats that had been sanded smooth. In this case the only places it had sanded through were at a few of the corners. What I may do is sand this smooth and only recoat areas that sanded through, leaving them a little rough.

I didn't get any pictures of what the epoxy looked like before it started to "curdle" but I can assure you that it went on very smoothly, just a few brush lines.
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Re: Getting fed up with MAS epoxy

Postby craig on Sun Sep 13, 2015 10:09 am

100% that is amine blush or surface contamination. Wash vigorously with soap and water and a scotch pad. It's exactly what mine looks like when I don't wash it. Besides amine blush, it could be from an oily coating from a gasoline engine or something. Whatever it is, my money is that washing will fix it. You may need to sand completely down to the wood over that whole area and start fresh, but it will build up properly
Titania, launched January 2015
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