Long story short: I got a flagpole for free. When I write "flagpole" I'm being generous. It's 14' 8" of 2" ID, 0.125" thick aluminum tube with a cleat about 11" from one end.

It's in lousy cosmetic condition.

After pricing flagpoles, I'm going to rescue it. (Details in another thread, later.)

150 grit wet/dry sandpaper seems to be taking off the oxidation, paint; dried-up, hardened tape adhesive, etc. fairly easily. I'll follow with finer grades and probably finish with steel wool. Now the question becomes: How to protect it from rapid re-oxidation?

Wondering if one of the modern, high-tech, liquid car waxes, re-appied once-a-year, will do the trick?

Jet-Hot powder coating.

Powder coat it. There are a fair number of shops with large ovens. Likely it will cost you a small penny, but not a huge sum.

Large Scotch brite pads will be nicer to work with than sand paper. I honestly know nothing of preserving the material for outdoor use.

Clarification: Spending any Real Money for this is not an option.

Most aluminum simply coats itself over time with a thin coat of transparent aluminum oxide, which prevents further corrusion. I don't understand the problem.

flashguy

Corrosion-X or Fluid Film would be worth checking out. I think I saw Fluid Film at local Lowes. I would think a good car wax might work well also.

quote:

Originally posted by ensigmatic:
Long story short: I got a flagpole for free. When I write "flagpole" I'm being generous. It's 14' 8" of 2" ID, 0.125" thick aluminum tube with a cleat about 11" from one end.

It's in lousy cosmetic condition.

After pricing flagpoles, I'm going to rescue it. (Details in another thread, later.)

150 grit wet/dry sandpaper seems to be taking off the oxidation, paint; dried-up, hardened tape adhesive, etc. fairly easily. I'll follow with finer grades and probably finish with steel wool. Now the question becomes: How to protect it from rapid re-oxidation?

Wondering if one of the modern, high-tech, liquid car waxes, re-appied once-a-year, will do the trick?

Steel wool guarantees corrosion by embedding steel particles in the aluminum. Some times of abrasive papers will, too.

Bead blasting or chemical stripping is best.

Corrosion treating is also best done chemically. If you can't manage that, then order some zinc phosphate or zinc chromate paint after cleaning it up, and spray it, then cover with the color of your choice.

Aluminum corrodes easily; you can polish the flagpole, but you'll be forever repolishing it to take off the surface corrosion.

After you get it sanded clean, you can allow the aluminum to form a natural oxidized layer. This layer will harden and is actually, "natural anodize".

It will show as a light dusty coating.

That will provide protection from further rapid corrosion.

Otherwise, you need a good chromate type etching/primer and properly applied epoxy clear or color coat, and that takes some specialized equipment to do adequately.

Never dull + lots of time/patience + elbow grease.

You'll work the never dull until the black residue goes away.

Thanks for the suggestions, all!

Guys, it's more than just oxidation. There's paint that's been dripped on it, other stuff that's discoloured or stained the surface, hardened old tape residue (looks like from that fiberglass shipping tape?) and God knows what else.

Good point about the steel wool, sns2guppy. I'll forgo that.

I'll try the Scotch-Brite pad, as suggested by David Lee, but I doubt anything less is going to touch most of what's going on with this pole.

To paint it, strip off everything that is rough, old paint, etc. Sand with sandpaper as needed. Mix up some epoxy paint, then quickly do some final sanding and put the first coat of epoxy paint on within minutes.

Letting the prepped aluminum oxidize after sanding it, by waiting hours, guarantees a failure in the painting.

If the tube in 7000 series aluminum, it absolutely needs coating. 6000 series is moderately corrosion resistant, and 5000 series does not need paint.

If you do end up polishing it, nothing works as well as Mothers, on aluminum.

Scotchbrite works; the walmart scotchbrite is just two grits, but it can be purchased down to very fine grits and is a good choice for surface removal on aluminum, especially where material removal isn't a problem.

Corrosion protection is best done with alodine. You'd indicated that you didn't want to spend anything on this, so alodine may not be your preferred method. Alodine uses a two-part process; the first is material prep, and is called alumiprep. It will acid etch the material and leave it very clean, but also very susceptible to corrosion/oxidation.

The second step is immersion in a solution made up with water and alodine (can be had in solution or in a powder); it turns the material a golden or bronze color, and it's then painted. This provides more protection, and is usually followed up with a chromate primer, then a paint.

As another poster noted, pure aluminum oxidizes and actually provides a protected layer. Aluminum sheeting, for example, comes as "alclad," which is aluminum coated in a pure aluminum which is sacrificial: it's job is to oxidize and provide a protective layer for the sheet. Any time the suface is disturbed by mechanical means (abrasive paper, etc), something needs to replace that protective coating.

Anodizing is popular, but difficult on an object as big as what you're working with, and it does reduce the strength of the part. (Alodine can very slightly weaken the part, too).

If you want it polished, you can remove the surface issues and then polish with mothers paste polish; a project that big will be easier with a motorized buffer. It will ultimately leave a deep polish. Traditionally the polish residue in the metal is removed with corn starch, but mothers leaves a deep polish with a slight black to it, which I like. Corn starch lessens that slightly.

If you go with a clear coat, the aluminum will often dull or corrode under the clear coat. Surface prep is everything, but so are the conditions under which its done, and the time frame.

If you do polish, once rain hits it, you're starting over. (I used to fly a version of the B24, which took an ungodly amount of polish, which was ruined by rain, and was an endless amount of effort to keep even sections of the airplane polished--ask me how I know...).

For the paint that's on the metal, start with some paint stripper. It will save a lot of time.

^^^
Yes. All that.

This is an excellent stripping agent.
https://solventkleene.com/d-zo...r-aircraft-depainter


It is low oder and acts pretty fast without any etching or effect on the surface metal.
It is thick, similar to yogurt consistency and clings well.


I ordered a "free sample" and they sent a pint, but I did have to pay shipping.
It was enough to do several jobs I had, and may be enough for your flagpole.

If you do use (any) stripper, purchase a package of the thin plastic "drop cloth" and wrap the pole after applying.
In the sun, the heat will help speed up the process and prevent it from drying out. (it is almost more difficult than paint to remove if it dries)


I covered it, and then used a pressure washer, but a hose with a good nozzle should work.

Hexavalent Chrome (Cr6), unfortunately its green but it will stop oxidation.

Thanks for the additional comments, guys!

The cleaning part is pretty much about half-way or better there. I'm now up to 500 grit wet/dry sand paper and it's looking 100% better than when I received it.

Had to cut the cleat off with my angle grinder. None of my drill bits were very effective on the screws.

When the sun gets off-peak (sun burn!) I'll get back out there, finish-up the 500 grit, give it a quick once-over with 800 grit, hit it with the Meguiar's liquid stuff I have and call it a day.

After that I'll let nature takes its course. I'm not trying to make this shine like chrome. I just wanted to get the worst of the ugly off. I think that, with what I've done, it'll look fine from anything more than 10' away, and that's all I need.

Once you get it cleaned up and optionally polished (if that is what you like) maybe Cerakote Clear. You would need a way to apply it (spaygun, etc). Ready to spray - no mix or oven cure.

quote:

Originally posted by smschulz:
Once you get it cleaned up and optionally polished (if that is what you like) maybe Cerakote Clear.

Fascinating. I don't think I'm going to go that far, but, boy, if I wanted a really shiny flagpole it looks like that would be the way to go.

This piece of aluminum has too many pits to make going that far worthwhile. Mainly what shining it up that far would accomplish is to accentuate the flaws--some of which are so bad getting them out would weaken the tube.

I don't think your Alum has to be polished unless you like it that way. Brushed (basically light sand on the metal with 150-220-ish) then cleaned and coated would look good, IMO.
YMMV

Unfortunately a sprayer is one tool I've yet to acquire. Buying one for this project is a non-starter.