Painting Tanks?

[Leadking]

Be careful, NEVER use a paint or system that requires heat. Any good shop will be very cautious around any repainted aluminum tank.

 

[HungoverDiver]

No intention of repainting, just want to strip the paint.

 

[Leadking]

Strip away with any good chemical stripper!

 

[Eric Sedletzky]

I know this is an oldish post, but does anyone have a protocol/suggestions for stripping the paint off an AL tank?

It's already been mentioned to use chemical aircraft stripper, which will certainly work, but for me it's not practical because the stripper costs money, and I already have air power, a good air orbital sander, and lots of sand paper around.
I usually sand the bulk of the paint off with 80 grit just until I see aluminum, then I switch to something like 220 grit to clean up the 80 scratches. I finish the sanding with 400 grit which is polishable. Aluminum tanks always have etch lines or casting lines in the surface of the tank if you look close. As long as you don't go down too far beyond those marks with sanding you will be fine. To polish I use brown rouge (bar) and an 8" sewn cotton buff wheel that goes onto a right angle polisher/grinder. The speed should be about 3000 RPM. Run the wheel on the bar to load the edge up with rouge and use a steady back and forth motion. Don't sit in one place too long because there can be a good amount of heat generated with buffing. It is wise to move around the tank and return to an area several times. Do this on an empty tank. If you have any concerns about the safety of the tank after it's polished then get it hydroed when you are done.

 

[HungoverDiver]

Ok, bringing this up again (better than an new thread, right?) It's been almost a year since the last question, but moving, new job, less diving has made this a low priority. Here are the tanks with chipping paint. I like the suggestions above to sand off the paint. Do I need to polish or "finish" the tank to ensure it is safe from rust/corrosion? I'm worried about function over aesthetics. Want to do this before I re-VIP the tanks.

I tried using a steel scrub brush on the open spaces, and it made a fine powder that might be just deposited salt, or maybe aluminum? Perhaps that was a bad idea?

Catalina AL80 tanks, btw.

 

[Eric Sedletzky]

Ok, bringing this up again (better than an new thread, right?) It's been almost a year since the last question, but moving, new job, less diving has made this a low priority. Here are the tanks with chipping paint. I like the suggestions above to sand off the paint. Do I need to polish or "finish" the tank to ensure it is safe from rust/corrosion? I'm worried about function over aesthetics. Want to do this before I re-VIP the tanks.

I tried using a steel scrub brush on the open spaces, and it made a fine powder that might be just deposited salt, or maybe aluminum? Perhaps that was a bad idea?

Catalina AL80 tanks, btw.

View attachment 220277

Open aluminum will corrode less than painted aluminum simply because the metal can breathe and dry out.
All that scale and white crap(white rust) on your two tanks is because water got underneath the paint and creeped sideways then blistered. Bare aluminum won't do that, it will just form a dull haze patina and stay like that. Any problems are clearly visible and won't be obstructed by a coating. Polishing is some work but it looks cool and it also doesn't give salt or minerals a place to "grab" onto. Water beads right off and they always seem to look great. The only thing that kills the shine is chlorinated pool water.

But, if you insist on painting them then there is a whole correct procedure to do that. You don't just rattle can some paint on and call it good.
The procedure is:
1. Strip all paint off by sanding or stripper.
2. Acid wash tank with alumiprep 33 and rinse thoroughly.
3. Treat tank with Alodine conversion wash and rinse thoroughly then dry.
4. Spray tank with a two part epoxy primer or etch primer - marine grade.
5. Spray top coat of two part marine polyurethane like Awl Grip or similar.

Refer to paint manufacturers specific recommendations on painting aluminum. Use only high quality two part marine paints as they are designed to protect aluminum in harsh salty environments with lots of UV exposure.
Even though it may seem like a good idea to use automotive car paints, they are not designed for impact resistance and rough handling or service work. Super tough and durable marine coatings are a way above any car paints.
I work with both, I'm the guy that knows.

 

[HungoverDiver]

Thank you. I'm not interested in painting, just removing the paint that is there and doing whatever need to be done to protect the metal (which sounds like I don't need to do much).
I may polish, depending on how much free time I have.


Sent from my iPhone using Tapatalk

 

[oldschoolto]

A qt of aircraft paint stripper for $10 bucks and some plastic wrap... And your done...

Jim..

 

[Eric Sedletzky]

BTW, both those tanks were painted with a transparent candy dye put into a regular automotive urethane clear. It has that "candy" look because you are seeing the reflective shine of the aluminum through the transparent candy color giving it that stained glass look. The problem is that unless the aluminum is treated properly nothing likes to stick so in order to candy them they have to spray the tinted clear right over untreated bare aluminum and it doesn't work for very long (as you can see).

for a while they were clearing bare aluminum tanks with just clear. I figure they did this to keep them looking shiny until someone bought them and they were off the dive shop property. Other than the sales aspect there would be no reason to put anything on them.

 

[HungoverDiver]

Alright, some basic paint stripper and some sandpaper got the job done. There is still some oxidation (??) or wearing where the original paint had chipped off before I stripped the rest. Will the remaining tank surface eventually oxidize as well? Just curious.

Also looked into polishing, but that seems to require tools, bouffant and other things I don't really want to buy.


Sent from my iPhone using Tapatalk