Repainting Aluminum

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
BrentMontauk17
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Joined: Fri Mar 17, 2017 11:18 am

Repainting Aluminum

Postby BrentMontauk17 » Mon Feb 25, 2019 9:50 pm

The [aluminum frames surrounding the] black console hatches have seen better days. I want to repaint them and have it last. Give me your thoughts on the correct way to do this.

6854ABFD-9F37-467A-BB85-989AB74A023F.jpeg
Fig. 1. Missing and blistered paint on aluminum surrounds of hatches.
6854ABFD-9F37-467A-BB85-989AB74A023F.jpeg (79.12 KiB) Viewed 8249 times

rtk
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Powder coat instead of paint

Postby rtk » Tue Feb 26, 2019 6:58 am

Hello. Look into powder coating: https://en.wikipedia.org/wiki/Powder_coating

In my area there are local shops that do this type of work, so you should be able to find someone in your area or you could ship the parts to a well recommended vendor.

Rich

BrentMontauk17
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Re: Powder coating

Postby BrentMontauk17 » Tue Feb 26, 2019 8:31 am

Thanks Rich. Not a bad idea. Anyone do this themselves?

jimh
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Re: Repainting Aluminum

Postby jimh » Tue Feb 26, 2019 8:50 am

The KRYLON brand of spray paint in aerosol cans would be a good choice for repainting the frames, if they are aluminum as the seem to appear in Fig. 1.

Jefecinco
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Re: Repaint instead of powder coat

Postby Jefecinco » Tue Feb 26, 2019 9:42 am

Powder coating looks good and we see a lot of aluminum T-Tops coated that way. The potential problem with powder coating is that when nicked or chipped it begins to lift. Touch up painting does not last well on powder coat. Given the propensity of console hatches to be badly treated I would use spray paint. Paint can be regularly maintained with touch ups and is durable. Cheap, too.
Butch

vze2gbs4
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Re: Repainting Aluminum

Postby vze2gbs4 » Tue Feb 26, 2019 10:00 pm

Remove all hardware leaving hatch frame alone.

Use paint stripper and remove all previous black paint.

Sand down all dust and rust.

Wipe with laquer thinner.

Once frame is ready do two-stage painting.

Use metal gray primer first.

Once dry use appliance-refrigerator black paint. Any good hardware store should have it.This paint will hold the best on a sun and will not flake or peel off. It's as tough as nails and cheap.

I [repainted] many [Boston Whaler] hatches using this method with great succes and durability.

I do not like powder coating because it chips and scratches very easy. I prefer the smooth factory look of regular spray paint.

BrentMontauk17
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Joined: Fri Mar 17, 2017 11:18 am

Re: Repainting center console hatches

Postby BrentMontauk17 » Wed Feb 27, 2019 6:51 pm

Thanks VZE. Just what i was looking for. Any particular stripper you would use?

jimh
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Re: Repainting center console hatches

Postby jimh » Wed Feb 27, 2019 6:55 pm

If the frame is aluminum, I recommend a special aluminum green primer.

Read my first-hand experiences at

http://continuouswave.com/maintenance-logs/paintSkeg/

BrentMontauk17
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Joined: Fri Mar 17, 2017 11:18 am

Re: Repainting center console hatches

Postby BrentMontauk17 » Wed Feb 27, 2019 8:05 pm

Thanks Jim. I have some self-etching primer that I will use. Appreciate [the advice].

jimh
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Re: Repainting Aluminum

Postby jimh » Thu Feb 28, 2019 6:45 pm

To clean metal before painting use acetone or alcohol. Also a good scrub with a detergent will remove oils.

Metal is not particularly porous.

Before any paint goes on, the metal should be clean and dry. Acetone and alcohol evaporate quickly and leave no residue.

I don’t know what lacquer thinner would leave behind or how long it would take to dry completely. It is a good solvent for lacquers, but a typical black spray paint is probably not a lacquer. I would first test lacquer thinner (or any other solvent or paint thinner) on a test piece before using on the actual workpiece.

If you are going to paint the surrounds on a few hatches from one boat, I recommend you ignore the cost of the paint being used. The time and work to prepare for painting will be long and more costly than any amount you could save by cheaper paint. And you probably will need only one can. Get good stuff and don’t worry about the cost of a premium paint.

dtmackey
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Re: Repainting Aluminum

Postby dtmackey » Thu Feb 28, 2019 11:27 pm

The pic you posted of the "paint" flaking looks more like powercoat and once powercoat starts flaking, it's difficult to get it to stop. My preference is to remove it and either have it powercoated again or prep for paint, which paint for aluminum take several steps.

I'll share my experience on a restoration I did 12 years ago on a boat I still own today and the powdercoat still looks nice.

For the powercoat removal, I used sandblasting with a black slag media.

Image

Media comes in 50lb bags and I usually buy 1000# at a time and store the rest for other projects.

Image

Blasting uses a large amount of air, so having a strong supply of air is key.

Image

Blasters are cheap and a 50# pressurized unit works great. I find the siphon feeds don't perform as well.

Image

Parts after blasting come out clean with enough surface prep to "grip" the new surface when applied.

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Drop them at the powercoater and then pick them up a couple days later looking like new.

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Image

I've since started using hydroblasting with a 4000psi pressure washer and find that it's more forgiving on the surface since the water keeps the surface temps down and also acts as a shock absorber for the blast media. I would have preferred this removal method over sandblasting on my boat project. I will be using hydroblasting for the door and window frames on my other boat this spring and having those powercoated.

D-

BrentMontauk17
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Re: Repainting Aluminum

Postby BrentMontauk17 » Sun Mar 03, 2019 5:33 pm

Looks great. Don’t have access to a blaster so I am stuck with using other means. I bought some aircraft paint remover. Now i must wait until it is warm enough for me to paint. I an getting six to eight inchoes of snow right now. Ugh. C’mon spring.

Hagler
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Re: Repainting Aluminum

Postby Hagler » Tue Mar 05, 2019 12:49 pm

Looks great indeed. Blasters do magic on aluminum.
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jimh
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Re: Repainting Aluminum

Postby jimh » Tue Mar 05, 2019 2:31 pm

I can't tell much about the appearance of ANYTHING from a low-resolution digital image taken from a distance of ten feet. The powder-coating appears to be done well, but I am afraid it is really not possible to make much of a judgement from a small image.

I suspect that if you hire the sand blasting or media blasting, the more objects you can fit into the working area of the blaster, the more cost effective the process becomes.

Also, to remove the existing paint or top coating from these hatch frames, it appears that you would have to remove the translucent plastic hatch material from the frame. I don't know how difficult that would be.

As always, there are often several good solutions to a problem.