Aluminum and bleach??? What did I do???

I needed to get a rear brake carrier for my sons YZ 400f. The shop wanted an arm and a leg for it, so I looked on ebay. I found one, the price was right, so I went for it.

The carrier arrived. I assumed the previous owner used it in the Paris to dakar rally just after he completed the baja 1000. It looked rough. Covered in oil, and scratched. Still it was functional.

I cleaned as much as I could. At the same time I happened to be cleaning my garage sink with bleach. I went ahead and tossed the carrier in the sink. Hopefully this would eat away some of the grease. I got distracted. 20 minutes later I went back and the aluminum carrier was a dark black color.

I cleaned the bleach off and sprayed the carrier with oil. This morning it looks great. The color is dark grey...similar to a hard anodized color. It appears as durable as any stock finish.

My question is...What the hell did I do? How does the bleach turn the aluminum black????

It looks good enough that I may try "bleaching" some of the other trashed parts on the bike.

Damn, now I know how Thomas Edison felt. LOL

Not sure if it just changes the color or actually does any damage, BUT some citris based degreasers will do the same thing to aluminum. I've had personal experience with "Purple" degreaser and a set of Mazda B2200 pistons (don't ask, I was a kid). I will say those pistons were still going strong 30k miles later (about 195k miles total on them) when I gave the truck to a college friend, so maybe your brake caliper will be OK after all.

Now Mr. Edison, stay away from the electricity! :applause::banghead:

Hey this sounds interesting, can you post a pic?

i might get bleaching if it doesn't affect strength?

Yes, it was a chemical reaction, much like Copper turning green, that aged your aluminum.

For the short period of time that it was in there, you did no damage.

You could buff it out if you wanted to.

You just oxidized the aluminium like steel rusting.

I think the dry powdered cleaners like comet contain aluminium oxid and bleach, but they don't react with each other until mixed with water.

I can take a picture, but have no idea how to post. The color is great. It looks like a dark, hard anodized finish. Much better looking than stock.

I might try some of the old, ugly aluminum parts. It looks better now than before!

I can e mail a picture if you contact me at

bleach+gas in car's gas tanks makes rust within 13 hours....oh, wait, what was the question? lol. it should b fine. if it shatters, you'l know it lol.

The color looks excellent. Several shades ddarker than bare aluinum.

I thin i will run it. I cannot imagine it being damaged.

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