Work boat and paint over a soildly bonded existing but worn paint surface

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Sobie2
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Joined: Tue Apr 15, 2008 12:27 pm
Location: Juneau, AK

Work boat and paint over a soildly bonded existing but worn paint surface

Post by Sobie2 » Mon Jun 26, 2017 1:24 pm

I have a 1998 painted aluminum landingcraft from Harbercraft boats. It has a ton of dents and paint scratches on it. I have been in the process of trying to sand and remove the paint, but it was originally painted with a great multi step process resulting in a durable finish. But my boat now has lots of scratches, and dings, and some areas with corrosion pitting and peeling. I have spot sanded most of the pitting and peeling.

My original plan was to strip it all, and leave it bare, but that is a time waste with all the dings. So I am now thinking to scuff the surface and maybe use an aluminum chormate type rattle can (Moeller brand) on the areas I sanded to bare metal, and then spray or roll some kind of paint on the rest. But I don't know what to use? Any recommendations? Think inexpensive

Sobie2

Chaps
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Re: Work boat and paint over a soildly bonded existing but worn paint surface

Post by Chaps » Mon Jun 26, 2017 6:50 pm

There's all kinds of paint systems you could use, one way would be to give the boat a light sandblast to clean everything up and get a consistent profile on all the surfaces, apply a coat of multi-purpose 2 part epoxy, scuff that up and then roll on whatever topcoat enamel you might want on there. Want easier, cheaper, fast and tough? Scratch it all up with a d/a sander and roll on a coat of DTM waterbase industrial paint from your local name brand paint store. Surprising how durable that stuff is.
1987 24' LaConner pilothouse workboat, 225 Suzuki
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kmorin
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Re: Work boat and paint over a soildly bonded existing but worn paint surface

Post by kmorin » Tue Jun 27, 2017 10:38 pm

Chaps, a question and one that Sobie2 might want to consider testing?
I was told by a friend who shoots automotive and airplane paint for a living that he's seen some reactions between newer paints and older films already on - that weren't fully removed?

The issue was a PPG series (don't know the type or series of product) used on airplanes that will 'bubble' if the older paint is left on? So... (doggone it!) I rubbed a couple million aircraft rivets clean of tiny rings of old Cessna paint before the painter would put new primer and paint over the wings!!! [free advise for any readers who have air craft owning friends- those that ask you to strip the wings of paint: shoot them and do the time- you'll come out better in the end: better yet- poison them so they die a slow and very painful death, then do the time -its worth it.]

We took some of the primer for the new paint system and dropped into the tiny rings around the rivets in the aluminum where the old paint was still hiding. AND... sure enough the mixture kind of bubbled up. My friend the painter said that some types of older paint are reactive with new. (as a result we hired a couple more guys to scrub the Dickens out of those wings!)

Chaps- will a spot test of new top coat or primer work to test if this potential reaction or bubbling is likely to happen? It would be an expensive re-work for someone to leave old paint that is 'roughed up' only to find that old film was reactive and marred the new topcoat?

Experience? I doubt that Sobie's boat has 1964 Cessna paint on it (?) like the wings I was working on- and the primer may not be as reactive in his planned paint system? But I think it might be worth testing the old and the new if Sobie is planning to leave old paint on?

Chaps, I'll defer to your expertise, I'm just curious. Painting boats and "doing windows" are both out of my work scope- generally. So I just want to make sure that we don't leave Sobie2 with inadequate advice?

Cheers,
Kevin Morin
Kenai, AK
kmorin

Chaps
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Re: Work boat and paint over a soildly bonded existing but worn paint surface

Post by Chaps » Thu Jun 29, 2017 1:06 am

I don't know if it applies to aircraft coatings (flying machines seem to have special rules for everything) but most paint incompatibilities can be overcome with the use of tie-coat primers that seal off the old coatings from the new. Also, oftentimes what one might think is a reaction between paints is really a reaction between the old paint and the thinning agent in the new paint. Make sure the thinner that you use to reduce your new product doesn't attack the old coating as if it was a paint remover.
1987 24' LaConner pilothouse workboat, 225 Suzuki
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kmorin
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Re: Work boat and paint over a soildly bonded existing but worn paint surface

Post by kmorin » Thu Jun 29, 2017 2:50 pm

Chaps, that is what the primer droplets on the old paint looked like- paint remover- the old paint "crinkled up" just like stripper- it kind of bubbled around the rivet heads- so it was probably the thinning/solvent component of the primer that reacted with the little rings of old paint?

Makes sense, there were half dozen cans of 'mix' for each layer of paint- I didn't really pay any attention to the brand or product but it sure was pricey! Anyway thanks for clearing up my (mis) understanding of the old to new paint interaction.

One thing I did notice comparing boat to airplane painting- I've put on boat paint that was much MUCH thicker! This entire film wasn't a few mills and that was primer and two topcoats! I'd say the plane's paint was 1/10th or less as thick as I've ever tried to spray paint on boats.

Cheers,
Kevin Morin
Kenai, AK
kmorin

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