Refinishing and blotchiness

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mhart
Posts: 2
Joined: Sat Jul 15, 2017 2:32 pm

Refinishing and blotchiness

Post by mhart »

I'm patching up and refinishing my Nomad. It's seen some heavy use and met some unfortunately placed rocks, and some of the scratches are deep into the epoxy. The trigger was finding that two spots on the keel are worn right through to the wood.

Because of the large number of deep scratches I decided to strip the varnish off the whole bottom. After stripping it with a scraper and sanding it down, it's looking very splotchy.

I posted two pictures over here: http://imgur.com/a/SomrB.
The first picture is while sanding, with the white spots attracting more than their share of dust. The second one is after washing it down, it's still quite visible.

With enough sanding I can sand out the white parts in the first picture, but I'm not sure what I'm actually sanding. I can't tell if it's varnish that I didn't strip off enough of, or if it's a layer of epoxy that didn't adhere properly. When I originally fibreglassed it almost ten years ago, I went with three layers of epoxy a few hours apart, but I remember that after sanding it, there were a bunch of places that didn't have enough epoxy on it so I gave it a fourth coat that would have been weeks after the original coat and mechanically bonded. I'm hesitant to sand it all out without knowing what it is.

Any ideas if it's varnish or expoxy? Should I leave it as is or sand them all out?

thanks!
mike
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Cruiser
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Joined: Sat Apr 27, 2013 10:21 am
Location: Bowmanville, Ontario

Re: Refinishing and blotchiness

Post by Cruiser »

Mike,

When the hull is being sanded, it can be difficult to see what the hull will look like finished.

Did you still see the uneven areas when you had the hull wet? That would be the best time to judge whether you have a problem or not, IMO.

Since you will be taking off the varnish, some areas are worn to the wood and some scratches have penetrated the epoxy, I think I would be rolling on a couple coats of epoxy to seal and strengthen the whole hull. If you decide on this route, you can sand as you see fit (obviously not into the glass) knowing the hull will be getting more epoxy.

If you didn't initially put bias cloth on the bow and stern, would be easy to add them now while the boat is prepped.

Brian
sedges
Posts: 325
Joined: Fri Jul 09, 2004 5:37 pm
Location: georgia

Re: Refinishing and blotchiness

Post by sedges »

What it looks like when it is wet with water is pretty much what it will look like when the new finish is applied.

If you have abrasion down to bare wood make sure you let that wood dry thoroughly before you seal it back up.
mhart
Posts: 2
Joined: Sat Jul 15, 2017 2:32 pm

Re: Refinishing and blotchiness

Post by mhart »

Thanks for your advice! I started scraping/sanding out the blotches and I'm fairly confident that it's the last coat of epoxy I put on. Seems almost like it's softer than the previous coats as it comes off fairly easily while the rest doesn't. I've no explanation for it, but it'll be much better once that layer is off.
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Jim Dodd
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Joined: Wed Feb 08, 2006 11:08 pm
Location: Iowa

Re: Refinishing and blotchiness

Post by Jim Dodd »

Guessing the last coat of resin wasn't mixed well enough, or possibly the mix ratio was off.

Jim
Keep your paddle wet and your seat dry!
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