Is it possible to change colour of anodizing without re-anodizing?

[_UPz]

Hi guys!

Do you think it is possible to dye the anodizing of a light without anodizing again?

I mean, you must know that you can remove the anodizing of aluminium lights with sodium hydroxide (*). I've did this a few times to leave flashlights in bare aluminium, to leave it like that (looks like bread blasted) or polishing.
If you put the light in the chemical bath the right amount of time, you will notice that the old ano starts to break down, leaving the dye "trapped" inside the porous surface by the sealing go out.
Maybe, if we stop the bath just at the time that the "first layer" of ano is out, we can clean most of the dye with acetone or some other solvant and dye again the surface just like it was "new" anodized part, and seal it again.

What do you think? I'll love to dye some of my regular black lights to other colours... but anodizing aluminium full process seems to be too tricky.

(*)PLEASE NOTE: Sodium hydroxide is an extremely dangerous chemical. Read and follow all the warnings. Use eye protection, and long chemical resistant gloves and do it in a good ventilated area, and of course don't breath the vapours of the chemical batch.

 

[StarHalo]

Just strip your light and then take it to a local powdercoating place, any color/finish you want..

 

[AnAppleSnail]

Can't you bake the anodizing and make a pretty bronze-ish color?

Click

 

[HarryN]

Interesting question. This is pure speculation, but assuming that the dye color is primarily organic in nature, then dipping it in (cold) H2O2, or a fairly strong oxidizing environment (example damp ozonated air) would reduce the color intensity substantially. It might be enough to re-color over this. H2O2 can work pretty fast and aggressively, so testing a few drops on a small area would be a good idea.

If the color is mostly from metallic coloring, then possibly a hot ammonia water mix might help.

Sounds like a good experiment for an old mag.