Gunked-Up Brass

[Keith Starosta]

Five years ago, when I inherited my Dad's shop after he passed away, I brought home a few things that were pretty unique. One of them was this...



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My Dad once told me that this set of concrete stamps belonged to his grandfather, who was a civil engineer with the Michigan Department of Transportation. He was one of the designers of the Davidson Freeway, which is the oldest freeway in the United States. As far as I can tell, these stamps are in the original box, and still are pretty gunked-up with concrete dust and dirt.

I didn't think much of these, until I was showing them to my father-in-law yesterday. He made the comment that I should try and clean them up a bit and see what they look like. I wasn't expecting much when I pulled out my Dremel with wire wheel, but got a bit of a surprised when I saw some shiny, brassy-looking color below the grime. So at that point, I fired up the bench grinder and spent a couple of minutes at the wire wheel. BOY, was I shocked with what I found!!!



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I did some searching based on the markings on the stamp, and found the website for Schmidt Marking Systems. They claim that, "...Geo. T. Schmidt, Inc. has been a worldwide leader in permanent metal marking machines, technology and services for over a century." Sounds like I got the right place! I'm going to contact their public relations department to see if I can find out more information about this set of stamps.

My question to you guys has to do with how to get all of the dirt off of the stamps. The wire wheel and Dremel do a pretty good job, but I can't get the grime out of the crevises. Is there something that I can soak these things in? I want to make sure that I don't damage the stamps, but I'd love to get them all sparkling again.

Thanks for your help!

- Keith

[Jim Becker]

I wonder if electrolysis is the answer...Neanders often use it to clean up old plane parts, etc.

[Keith Starosta]

I had actually thought about that. I know there are some pretty decent DIY plans out there. I was hoping for something a little bit less time-intensive, but if I have to go that route, I will.

- Keith

[David G Baker]

Keith,
Phosphoric acid is used to clean cement/concrete off of steel. It is used to clean up concrete tools, etc. I do not have any idea of how it will react with brass but you may be able to do a Goggle and find out. I believe that an acid is better on non ferrous metals than caustics.
I do not know of the dilution recommended either.

[Charles Wiggins]

I had actually thought about that. I know there are some pretty decent DIY plans out there. I was hoping for something a little bit less time-intensive, but if I have to go that route, I will.

- Keith

Keith,

We used to use low power sandblasting to clean up castings. Can't remember the PSI we used, but you don't want to do high pressure blasting like is used to etch granite. After they're cleaned then you can wire-wheel and buff them with wax or rouge to get a polish if you like.

If you choose to try acid, use muriatic acid, not phosphoric. I prefer the sandblasting myself.

[Jim Becker]

We used to use low power sandblasting to clean up castings.

On a similar note, using bicarbonate seems to be an interesting alternative to more aggressive abrasives for blasting. In an Eastwood catalog I recently read (and subsequently threw out...) they were touting it for paint and rust removal without damage to rubber and glass in automotive body work...

[Matt Meiser]

I wouldn't blast them with anything as it would remove all of the patina. A mild chemical seems like it would be better, but again you don't want something that will leave an etched surface.

[Rich Engelhardt]

Hello Keith,
Ask around if any of your friends reloads ammunition.
The vibrating cleaners used to "tumble" brass casings will slick those up real nice.
A few hours in the hopper w/crushed walnut shells or crushed corn cobs and they will look like new w/out scratching it like harsher abrasives will.
It will also not ruin the stamped lettering like harsh chemicals or hard abrasives will.

When mine isn't busy cleaning up .44 & .45 cases, I use it to clean cabinet fixtures and hinges.

Dillon Precision makes an additive which will cut the time down also plus leave a shiny semi-coating on the brass. Any gun store that sells Dillon reloading supplies will carry it.
A cap or tablespoon full of mineral spirits added to the nut/cob also works, but is pretty stinky.

[Keith Starosta]

Thanks alot for all of the suggestions, guys. I appreciate it!!

After I get these cleaned up a bit, I'll repost pictures. I'd also like to find out if there is any antique value to them, or if they'll just continue to be sentimental treasures.

Regards, and Happy New Year!!

- Keith

[Pat Germain]

As you might imagine, I had to clean a lot of brass when I was in the Navy. For small brass fixtures, such as you have there, the best thing to use is plain old Kool-Aid. Seriously, forget about expensive chemicals and blasting.

Just mix up some cherry Kool-Aid, without sugar, and drop your brass fixtures into it. Let it soak for several hours; even overnight is OK. The absorbic acid in the Kool-Aid will eat away all the gunk without damaging the brass. It will come out looking shiny and new. Kool-Aid is much more effective and safer than a grinding wheel. It's also incredibly cheap, which is why it's used by the US Navy. In the Navy we called it "Bug Juice", but it's just Kool-Aid.

[Rick Gifford]

As you might imagine, I had to clean a lot of brass when I was in the Navy. For small brass fixtures, such as you have there, the best thing to use is plain old Kool-Aid. Seriously, forget about expensive chemicals and blasting.

Just mix up some cherry Kool-Aid, without sugar, and drop your brass fixtures into it. Let it soak for several hours; even overnight is OK. The absorbic acid in the Kool-Aid will eat away all the gunk without damaging the brass. It will come out looking shiny and new. Kool-Aid is much more effective and safer than a grinding wheel. It's also incredibly cheap, which is why it's used by the US Navy. In the Navy we called it "Bug Juice", but it's just Kool-Aid.

I guess bug juice is still used. We used it to clean the deck plates in the engine room.

You can also mix it heavy and make a paste and apply it directly on trouble spots.

Keith I am not sure if this is your answer to getting old concrete out of the crevices, but it does clean metal parts pretty well. The stuff is cheap enough to give it a try.