Paint question for aluminum hull boats

[Ironhorse2022]

Hello everyone. Just brought this 56 aero craft home today and am starting to prioritize repair items. The blue hull panels have a single semi transparent (and dusty) rolled coating of Rustoleum Top Side paint. It appears to have good adhesion. Wondering if it’s necessary to strip it or just sand it smooth and recoat in a urethane or polyurethane paint. I don’t have spray capability (or skill) so will be trying my hand at roll and tip technique. I know the Rustoleum aerosol paints are oil based and so not compatible with some other types of paint. Not sure yet about topside however. Feedback on technique and paint types/brands appreciated.

 

[Scott Danforth]

welcome aboard

I would simply sand, and where you sand thru, use a good zinc etching primer.

see link #19. https://forums.iboats.com/threads/how-tos-and-other-great-information.283508/

 

[Bondo]

Ayuh,.... Welcome Aboard,..... I'd sand it smooth, 'n use Rustoleum enamel, with majic hardener in it,......

 

[Ironhorse2022]

Thanks guys. I seriously doubt a zinc primer was used under the 1 yr old coat of Rustoleum Topcoat that’s on it now. Adhesion looks good but who knows. How serious an omission is the primer ? Would a second coat of Rustoleum tc with hardener over the original coat without hardener be a problem ? I’m thinking probably not.

 

[Scott Danforth]

aluminum requires a good primer for adhesion

paint sticks to primer, not to aluminum

 

[Ironhorse2022]

Can you explain a bit more ? I just spent the afternoon sanding down all the runs, bubbles and . Whats left sure seems stuck on there well. Is there an adhesion test I can do ? Can’t scrape it off with my fingernail. I’m not arguing that an etched primer base is better. Just in denial perhaps.

 

[Scott Danforth]

Can you explain a bit more ? I just spent the afternoon sanding down all the runs, bubbles and . Whats left sure seems stuck on there well. Is there an adhesion test I can do ? Can’t scrape it off with my fingernail. I’m not arguing that an etched primer base is better. Just in denial perhaps.

whats there to explain.

unless you have a baked on paint from the factory, you need primer

 

[Ironhorse2022]

All right then. Thanks.

 

[airshot]

Are you painting over bare alluminum or previously painted alum. ?? Reson being ifvthe previous paint is sticking well you might be alright. My jon boat has been painted a number of times, but over the years some faded, some just wore thru, but none has actually peeled off. I paint it about every 6-8 years with rustoleum..Never used a primer because it never got down to bare aluminum.. With that said...a good primer will give you the best finnish and long lasting finnish.

 

[Ironhorse2022]

It had been bare paint until the PO painted it about a year before I bought it. No primer although he may have used an etch because that paint was really stuck well. Still, it may have pealed off in a year I suppose, who knows. With the various opinions expressed here and the fact it only took about 6 hrs to sand it back to bare and agreement that primer base is better, I sanded it down, did a mild etch w vinegar and water, primed with Rustoleum alum primer. I now have 1 coat of Rustoleum topcoat rolled and tipped. Second coat going on today and one more for good measure tomorrow. It’s really difficult to keep the paint coats thin enough to avoid runs and orange peal but I’m getting a system down. I used some Magic brand hardener in the paint and thinned it 5% with mineral spirits to help it flow away the tipping marks. FYI, I was very impressed with the Rustoleum alum primer.

 

[Ironhorse2022]

Well, all done. My first attempt at rolling and tipping. Boat looks great from 5’ but I’m afraid my tipping leaves a bit to be desired as many brush lines are clearly visible. I thinned the Rustoleum 5% with mineral spirits which is the max recommended on the can for brushing. It’s hard to imagine more thinner as drip-control was pretty difficult (looked great initially but would sag after 3-4 minutes). I also used Magic brand hardener at the recommended ratio and Rustoleum alum primer underneath. Overall I’m pretty happy. The gloss is great and I feel good about the adhesion. On to the next task which is what to do with the exposed inside hull. This boat has no subfloor not structure to attach one (nor do I really want one). Due to all the rivets sticking up (and ribs) I’m considering rubberized paint or marine carpet (removable for cleaning). This will not be a fishing boat. Appreciate any input on floor finishing. Thanks