Painting aluminum

I have some stuff I want to paint. There’s some areas of corrosion, but most of it is pretty clean, it’s just that the pain is flaking off. Do I need to strip the entire thing and apply primer, or just remove the loose paing. And then would I apply primer over the whole thing, or just the bare areas. Or is primer for wood. How big of a deal is old lead based paint, providing I’m not a little kid eating the stuff? Can I do a decent job with consumer spraypaint?

id strip as much as i could off and prime the whole thing if i was going to apply a primer…i think you’d use one for bright metals. Some of the better spray paints advise they can go on over light rust - like Rustoleum.

People are pretty wound up about lead paint, they recommend testing things. the problem is with removing it the flakes will still be all over the place.

I found a site that advises on marine painting, which would be bulletproof enough for most purposes. You need to clean it down to bright metal, degrease it, sandblast it and use an etching primer for best results. As to the lead paint, I’ll leave that for someone else.

Assuming you’ve just got some aluminum “stuff” to paint and you aren’t painting an airplane or an Airstream, you can probably just sand it and paint it. The old paint fell off because someone did something with the old primer that failed and moisture got underneath. Aluminum’s like that. If you’re OK with painting it again in 10 years, just sand the bad spots and paint. If you want it nice, sand everything, prime the bare spots and paint it all. If you want it perfect, get ALL the paint off by sandblasting or something, prime it with self-etching car primer or equivalent and then paint it. The primer’s more important than the paint on aluminum. You can go over the top paint later with another coat or another color, but you can’t - as you are experiencing - get a second shot at getting the primer to stick to the metal.

Clean, then scour with steel wool, wash the surface with acetone, and then rinse with very clean water. Air dry, then apply primer. Get the marine stuff if you want a long lasting finish. If it won’t take abuse Rustoleum should be fine.

Is sandblasting within the realm of DIY or should I let someone do it that has the equipment and knows what they’re doing? FWIW I checked ads on Craiglist and found people offering to do this, I’m sure I could Google more… The biggest piece I can’t break down is about an 18" square box so I can easily move it around. I’m concerned mainly with it looking nice, the paint is fading and peeling and the metal is starting to corrode after decades outdoors, but I’m going to keep it indoors. from now on.

If you had the stuff to DIY sandblasting, you wouldn’t be posting here.

Call a powdercoating company and ask if they’ll blast it for you. Check their coating prices while you’re there. Wouldn’t it be nice to drop it all off and pick it up looking new for $150? Real sandblasting companies tend more toward big things like cars and bridges and can be difficult for small stuff.

No, I don’t have stuff for sandblasting, but Home Depot, Northern Hydraulics, etc. sells it… I’m trying to compare the hassle and expense of learning how to do it myself to the hassle of taking it to someone. (And I do want it painted, not powdercoated). Getting it done right with no mess on my part seems attractive, but so does just being able to blast a small part or two now and then in my garage without taking it someplace and finding someone willing to do it. I do have a 100psi air compressor, no clue if has enough capacity for blasting.

There is a special aluminum primer you can get. Used it when I painted my outboard motor. I got it from NAPA. Been awhile, think it was zinc oxide. Or am I thinking of an a@# creme. anyway, it worked good, especially on the bare aluminum. Check a parts house like NAPA, or a auto paint supplier.

A few people have mentioned marine paint. Just a warning, in some cases marine bottom paint contains copper, which reacts with aluminum. This is really bad for the aluminum. Only get marine paint that is specifically designed for aluminum boats.

My air compresser is one that my stepfather gave me, no manuals or anything

Coleman Blackmax B3511, Oil Free, 3-1/2 horsepower 11 gallon 135 psi, plugs into 110 AC.

Big enough to run a sandblaster for small aluminum parts or no?

I have a portable sand blaster from Harbor Freight. It’s cheap and will work on small parts. I think it cost about $30 on sale, and I spent another $25 on aluminum oxide, also on sale, but not much more than that normally. I’m not sure what the ideal media is for aluminum.

This blaster is not pressurized, it draws the media from a hopper. I work outdoors over a large plastic tarp to collect up the used media and put it through a fine strainer for re-use. When descaling steel it cuts a pretty narrow swath, less than an inch. But that should be fine for small parts.

HF also has a small pressurized sandblaster and a soda blaster, never tried them.