Another brass cleaning question ? Any metallurgists among us ?

[BigSlick]

Hi guys,

I have been doing a little experimentation with different ways to clean up brass.

I have used corn cob, walnut, wet ceramic, several commercial brass cleaning products, mineral spirits, NuFinish (and others) car wax, vinegar, rubbing alcohol and other such widely mentioned methods. I have avoided any method that involves abrasive etching of the brass or ammonia.

I have found a couple of methods that work like gangbusters.

One, cleans the brass in a wet solution by soaking for about a minute or so. That works for me, since waiting a couple of hours (or more) for clean brass isn't high on my list.

This method works very well, but I have noticed a couple of test cases that come out with a slight amount of pink staining on the case. 99% of the cases in a batch don't show the same effect.

Can one of you metallurgy guru's tell me why one or two cases in a batch come out with the pink staining ? Is this indicative of the brass being weakened ? Evidence of corrosion of another sort ? Something to worry about ? Is the copper or zinc being leeched out by the solution ?

When I get this all figured out, I'll post my findings. Not a huge issue to some folks, I know, but maybe it can save some of us old guys a few bucks, or help a newbie get started on the cheap.

Thanks in advance for the feedback...

BigSlick

 

[pauli]

might help if you mention what the wet solution consists of...

 

[R.H. Lee]

Acid?
http://www.finishing.com/4400-4599/4432.shtml
http://www.finishing.com/1600-1799/1730.shtml
http://forum.doityourself.com/showthread.php?t=212927

 

[svtruth]

Dezincification?

Not a metallurgist, but brass screws on boats that lose the zinc in the alloy turn the color (and consistency) of a pencil eraser.
Good luck.

 

[griz]

I've bought bulk brass that had some pinkish stains on a few of the cases. I still wonder what causes it, but I've never had a problem with any stained brass. That also includes brass turned brown by laying in the leaves and dirt for a month. Corroded brass is another story. Anything that actually eats into the brass is enough for me to toss it.

But I am curious about where the pink color comes from.

 

[mete]

I'm a metallurgist but I need to know what the solution is. I never care about getting bright and shiney brass. I always pop the primer and put the brass into boiling water with detergent. If you want it bright and shiney get a tumbler with something like walnut hulls....Stay away from anything with nitrogen or ammonia compounds they cause stress corrosion cracking of brass. To get dezincification takes some time and is more common with two phase brasses like yellow brass.But any solution that pits the brass is too strong and in there too long. Corrosion colors of brass are usually reddish because of the copper - red ,brown ,pink etc.Color may also be an effect from lubes and other things the brass has been in contact with. ..Always spend time inspecting brass looking for cracks, stretching [changes in texture] and obvious pitting .Brass is cheap ,when in doubt throw it out.

 

[obm]

i used Simple Green on my last batch and they cleaned up well and quickly. i know simple green is bad for aluminum, but does anyone know of any dangers with brass?

 

[The Bushmaster]

Mete...I'll bet he is using a solution of:

1 pint of water
1 cup white vinegar
1 tablespoon laundry or dishwashing detergent
1 tablespoon salt.

What's your thoughts on this particular solution??? It also turns badly tarnished brass pink. Or just in spots where it is the worst. But tumbles out just fine as far as visual is concerned...

 

[mete]

Vinegar [acetic acid] should be OK. A DIY cleaner for copper and brass is lemon juice [citric acid] and salt .Adjust the concentration and time so it does just enough and don't leave it in the solution too long.Shouldn't take long at all......BTW -Simple Green - Read their website , they say it's ok for aluminum ! It's a good idea however when using it on guns or anything else to rinse off any residue .That may be the problem some are having with SG.

 

[The Bushmaster]

Mete...I guess I should mention that you leave the brass in the above solution for about 20 and agitate it ever 3 to 5 minutes. Then rinse in clear water until there is no more sudsing...

 

[grendelbane]

Citric acid, (in powder form), is sold in 5 ounce cans for canning tomatoes. I have used this to clean brass, though I never added salt.

I am still experimenting trying to find the smallest amount that will work well in short time periods.

If all you have is pocket change then a packet of Kool-Aid will work quite well to clean brass.

What purpose does the salt serve? I assume we are talking about common table salt.

 

[The Bushmaster]

Salt? Yup.... What does it serve? Not my recipe. I just know it works...

 

[jungle]

Citric acid and trisodium Phosphate are two of the best brass cleaners. They won't make it shine, but they do get is clean. Neither are harmful to brass.
By the way, US government arsenals used dilute acid at near boiling temps to get their brass clean, but not shiny.