Thread: Restoring anodized aluminum?

Sorry if this is the wrong forum - I have an anodized aluminum part that's scratched and worn in one place (not quite sure what the term is, but it's untreated silver/grey - if it was black, I realize I could use Birchwood's restorer). I'd like to touch it up, but I realise that normally means reanodizing the whole piece; is there a simpler cosmetic solution? I've seen references to paint, but I'm not quite sure what I need.

Thanks,

N

One of the terms used for silver finished Al was brushed as it had that brushed look. Perhaps a brass wire brush may restore the look?

Michael

Apart from anodising, another alternative, is to have it powder coated. To paint it, requires a multi step process, sanding, etch priming undercoating and a finishing coat. Contact a specialised paint supplier, not your local hardware store.
Kryn

Some pictures of the item and just how high a finish standard you wish to achieve will help others to pitch a suitable answer to your question, but going on what you have stated, you will need to sand , or even file out and than sand the scratches, going with finer and finer grades of wet and dry paper till you are satisfied with the result. You could then re-anodise, powder coat or paint the item, depending on your requirements.
If you are going to powder coat or paint it, then you will not have to finish it to the same standard that you would if you are re- anodising, as powder coaters normally sand blast everything before powder coating it, although with aluminium they may soda blast it if they think that other blasting media would be too aggressive, i'm not sure about that.
Septone etch primer in a spray can is what I have used in the past,(from SuperCheap Auto) and they say to sand using 240 - 320 grit to give a good key to the primer. The next coat is a primer surfacer or a primer filler, followed by the top coat(s). You also need to clean the item thoroughly, using a wax and grease remover, before painting, and generally you should not handle the work without gloves to prevent skin oils from contaminating the surface.
You can anodise small parts at home, a power source such as a battery charger or old computer P/s could suffice, some sulphuric acid and a suitable plastic or other acid resistant vessel to contain the process are the basic requirements, but sometimes refinements for smut suppression are used, google and youtube will provide you with most of the answers you might want if you go the anodising route. If you do re-anodise, then generally you would strip the old anodising away with a caustic soda solution first. Good luck what ever route you choose, and apologies if I have just waffled on and told you nothing that you didn't already know.
RT

Thanks all! It's a small spot (maybe 1'') in a wider frame. I'd really need a spot anodizer, but don't think that's a thing (at least easily).

Spot anodising (if it were an actual process) would also be a nightmare to colour match, as the appearance depends on the pore size etched into the aluminium by the sulphuric acid of the anodising solution.

All I can suggest is strip the anodise off (a quick bath in caustic soda...like 30 seconds) followed by scotchbriting it to an acceptable satin finish and then finishing with a varnish meant for brass doorknobs (the one available here is called Incralac).

If - and it's a big if, very dependant on the aluminium alloy - your part looks nice and clean and satin-shiny (and not smutty) after the caustic strip, you may be able to seal it by giving it a quick rinse (no touching with your hands) followed by 45-60 min of boiling in distilled water.

Thanks! Seems I'm out of luck here. One last shot - is it possible to achieve a close match with paint?

It will show. Because the light will reflect differently, even if you do get a perfect match for colour, from different angles and different light sources (sunlight, tungsten bulbs, fluorescent tubes) I would expect something to be noticeable.

Michael

The closest I could suggest there is:
Get a really close match colour.
Spray it on the damaged area.
Thin the paint 50%
Spray it on a larger area (like half again as big).
Thin the paint 50%
Spray it on an even larger area (half again)
Thin, spray yet again.

You should now have blended the repair over a large enough area to make it less obvious (or make it look like a horrible mess depending on your skills and the type of paint).

Murphy being Murphy, if it turns out to be a really good match, the paint won't stick well to the alloy. If it looks horrible, you'll need to use 40 grit to remove it.