Removing surface rust from black-oxide parts

[ThinWoodsman]

To put this in context, I have a large cabinet of hardware I purchased from the son of a deceased local machinist (the son is a great guy, btw, and was happy to find a home for the more mundane items his father used regularly). There are socket cap-screws and nuts for the standard sizes and then some. Thousands of items, really, and most of them are a) black oxide coated, and b) have surface rust on up to 1/4 of the part.

I know I can use evaporust or electrolysis or purple-power-in-the-ultrasonic-cleaner, but all of those will remove the remaining oxide, and I would like to avoid that as the parts themselves are in fine shape.

For now, I am using a nylon brush and lighter fluid to remove the surface rust on parts as I need them, but as you can imagine I am looking for a ways to just do these in bulk, drawer by drawer.

Any ideas? Maybe a different cleaner to use in the ultrasonic? A special medium for the tumbler I use to polish cartridge brass?

 

[Flyinfool]

Contrary to popular belief, black oxide is not a rust preventer, it is just for cometics. I would use your favorite rust remover that will also remove the black oxide, then get a bucket of Oxpho Blue from Brownells to make them black again and oil them good to put back in storage.

 

[royesses]

I use rust blue to make my parts black instead of black oxide. I use Hydrogen Peroxide and salt to quick rust the parts. Then card the rust don't remove the rust. Next I place the part in boiling water making sure it is fully submerged, when rust is heated in the absence of oxygen it turn to ferric oxide which is black. Watch the rust turn black as the ace of spades. Then oil it and done.
Perhaps try boiling a few parts and see if the rust turns black. Boiling should not remove the black oxide so no harm done.

Roy

 

[ThinWoodsman]

I've got a cheap hotplate and pot in the shop for experimenting with the peroxide rust-bluing, waiting partly on nice weather and partly on working through the backlog of projects currently covering the bench.

There are far too many parts for that method, though. This is a 2'x3' drawer cabinet of hardware ranging from 4-40 to 1/2, weighs at least a hundred pounds when full. I'll experiment with using Dawn (no water) in the ultrasonic cleaner and see what that does - otherwise, it's starting to sound like I should stick with my current spot-cleaning approach.

 

[derf]

Surface rust on black oxide is easy to remove with WD 40 and 0000 steel wool.

 

[ThinWoodsman]

In regards to being used as a cleaner/solvent, WD-40 is just kerosene with some other junk added. Nothing magic about it, though kero would be a bit overkill for this job.

Tonight, I tried two ziplocs with parts in them, chucked into the tumbler: one bag had baking soda, one had dawn. Well, the bags got torn up and the dawn just gummed everything up with media, so I chucked the parts in without bags and after an hour, they were clean enough to suit my purposes. A quick coat of mineral oil, and back in the cabinet they go.

Fishing parts out of the media, and cleaning the media from primer pockets socket caps, are a bit annoying, but this should serve for 90% of the parts. Will update if I find a better approach.