Cool effect on polished parts

[sunnbobb]

I polished a set of parts for Roady and sent them back to him. I mentioned he could toss them in a dishwasher to get them really clean. He did so, and the results were, well, unexpected. They came out with an almost medium black chrome finish. He fired them back to me, and i took them to the polishing machine to find that it was not corrosion, it had actually hardened on the surface. The finish would not cut with metal polish or easily with white rouge. The finish is still shiny but much darker. I kinda like it and am going to keep them and return a new set to Roady. I am waiting to hear from him what specific cleaning compound was used int he washer, as I would like to repeat the effect in the future. Check out the photo:

[Roady]

They were sort of cool looking and I almost just mounted them up like that. The only problem was that the fork lowers turned out kind of blotchy.

My domestic routine kicked in when I loaded the dishwasher with the parts and I popped a Cascade Gel Pack in there. You know, just running on automatic after 33 years of marriage.

[Rat]

A new look.

Everyone will want it.

Gord

[Slabghost]

I like it! Cascade! Who'd a thunk it? Was that also on the heated dry cycle?

[Roady]

Nope, just air dry.

We like to conserve energy whenever possible. (Just not when riding )

[reidransom]

It's the bleach in the detergent. You oxidized it a bit, which also explains the tough time polishing it back off; Aluminum Oxide is crazy hard stuff.

[sunnbobb]

Interesting. I think I will soak a part in bleach tomorrow and see what happens. The odd thing is that it is still shiny like chrome, rather than oxidized metal...

[reidransom]

I was pondering that myself. I can only guess that naturally age-oxidized aluminum looks all dull and nasty because it does so unevenly owing to grit and grease and scratches and so on. Starting with a highly polished and scrupulously clean surface, and doing it quickly and evenly probably accounts for the difference.

edit: I just put a bit of bleach on a sorta kinda polished bit of aluminum, and it did darken up, but didn't look so so shiny, not that it was polished all that well to begin with. It's either surface prep, or there's another factor in the reaction that's helping out. Strength of the solution, heat, residual stuff from the polishing compound, other stuff in the detergent, something. It's worth a bit of experimenting, at least.

[Whiskerfish]

You are basically doing the same as a bluing process on a gun barrel. It is a controlled deterioration of the surface metal and it will actually develop a protective layer. Same as an alodine conversion coating process when preparing aluminum for painting but harder.

[damagedduck]

very cool effect,i remember back in the 80's black chrome was the thing,it's starting make a come back,
ok so let me ask how do ya prep the covers after polishing?& will it leave a residue in the dish washer? 'cause my wife would beat me stupid-well more than i already am!

[sunnbobb]

After polishing, I wash the parts in mineral spirits to remove the polish grease, and then soap and water to remove the mineral spirits. You know WF, now that you mention it, it does have a slight blue cast to it.

[HOTT]

The mad scientist at NGW are at it again. Who'da thunk it. Today I'll be watching the Indy 500 with the dishwasher going

[sunnbobb]

[Roady]

We're working on acquiring a dishwasher that will hold an engine.

[CharlieP]

THAT is friggin' sweet !