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Discussion Starter · #1 ·
I have applied 2 coats of 2-part epoxy primer to the dinghy I've just finished building and now I'm ready to apply the 2-part PU paint. Should I sand the epoxy primer before painting? the primer has a pretty slick surface, almost a semi-gloss finish. Thanks in advance!
 

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Tundra Down
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YES! Epoxies are great! Tough and hard. The PU will only be tough. You can polish the epoxy with some careful sanding. Take it to 320 with a da sander. Epoxies also produce some contaminants on their surfaces after they cure. These contaminants must be removed!! Wash the boat. Sand the surface to complete its "cleaning" and wash it again. Tack it off with clean lint free rags and alcohol until you think it is ready then do it again! Remember, you will end up with the finished surface you start painting on. Hopefully the primer is thick enough to sand/polish a little. If not add some more.

It really depends on how "perfect" you "need" it to look when you finish. I am considering painting my Islander. Not sure if I will have time this spring but the old gelcoat is flaking off! It was re-gelcoated by a po and that job's adhesion is failing. Right now I am thinking I will skip the pigmented PU top coat and "polish" the epoxy then apply a clear PU top coat.

I am an experienced painter. Retired. I have sprayed many yachts with Awlgrip and done all the prep. I appreciate a good finish but don't need to see my clear reflection in my topsides. I don't want a fresh paint job to create another maintenance issue to worry about. The first thing that happens to your new paint job is it gets compliments and damage. A beautiful Endeavor Blue paint job on a 40' sailboat will require touch up if the boat gets any use. I am thinking I will use a supply of red epoxy primer I have in the shed. It has an indefinite shelf life and will be considered hazardous waste at some point if it doesn't corrode through its containers. I have many gallons and it is free! I plan to apply it with a roller and polish it. Its red color will be what it is. I am expecting sort of an oxblood semi gloss red. If it oxidizes I can polish it. I will apply a thick coating. What really appeals to me is having the top coat the same color as the primer (epoxy). When I bang into something a contrasting color of the primer won't create an obvious blemish. I can touch up any dings with more epoxy and buff it out. Choosing a top coat with a color similar to the color of the primer is smart. You can tint the primer, too.

Take all safety precautions and enjoy the process.:)

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Discussion Starter · #3 ·
Thanks for the advice Downeast! I applied the epoxy with a roller, so it's pretty thick. I'll wash and wet sand as suggested. The top coat will be white. I suppose I'll have to do 2 coats (with a roller). Do I have to sand between PU coats as well? I'm not looking for perfection in the finish... it's a workboat (dinghy) after all.
 

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Tundra Down
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Copa,

My pleasure.

2 part paints don't "dry" they cure. If your second coat is applied to a "dry to touch" surface that is clean it should be fine. Curing continues well beyond the "dry to touch" condition so it is technically uncured for a while. A second coat of the same paint will adhere. Tack it off with alcohol. Sanding is as important as a cleaning step as a smoothing step. If it is clean you should be good to go! Which pu are you using?

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Discussion Starter · #5 ·
I'm using a national automotive paint. It's what I could find here and it's soooo much cheaper than the marine stuff. I figure if it works on cars left out in the rain and sun, it'll work on my dinghy.

Thanks again for the tips Downeast!
 
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