Question about polishing agents


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cdrt
April 18, 2007, 11:24 PM
I was reading one of the other threads titled "media" and someone mentioned not to use Brasso as a polishing agent because it contains ammonia and can cause the brass to get brittle.
I've been using Brasso for years and never had any cases get brittle that I can tell. I have some .45 ACP cases that have been loaded in excess of 10 to 15 times and they still seem okay; granted I only load mostly light target loads. I have used it for my .44 Magnum cases and they seem okay.

According to the can label, Brasso contains petroleum distillates and silica. I checked online and Brasso contains between 2 to 3% ammonium hydroxide. I use about a tablespoon full in my Lortone tumbler (12 pound drum) with walnut media, so it doesn not take very much to get results, i.e. clean brass.

So, am I the only guy out here that uses Brasso? And has someone really had cases that got brittle from using it?

Navy Vet & SWIFT Boat OIC

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ReloaderFred
April 19, 2007, 01:16 AM
Years ago, a fellow worker, who was also a reloader, brought me some 7mm Remington Magnum brass and asked if I could help him figure out why they had failed the first time they were reloaded. The cases were extremely brittle and the brass was a funny color, so the first question I asked was what they were polished with. He said he had gotten the cases from his uncle and they were already shined when they were given to him. He called his uncle and was told that he had hand polished each one with Brasso while watching TV.

When the cases were crushed with pliers, they didn't bend, they cracked. My assumption was the Brasso had so weakened the brass that it was dangerous to reload.

That's the only experience I've had with brass that's been subjected to Brasso, but it was enough for me. A chemist friend explained that the ammonia attacks the zinc in the alloy. Cartridge brass is 70% copper and 30% zinc, so the zinc is a significant amount of the alloy.

I avoid ammonia for my brass because of this experience. There are plenty of other polishes that are made expressly for cleaning cartridge brass, so I have no need to take the chance with anything else.

Hope this helps.

Fred

Shoney
April 19, 2007, 01:17 AM
cdrt: The scientific reason WHY NOT TO USE any compounds with ammonia is:

Cartridge brass is 70% copper and 30% zinc. Ammonia leeches the zinc from the brass at a rapid rate, the longer the contact, the more that is leeched. A small reduction in the % zinc will cause the brass to be brittle and can cause catastrophic rupture of the case.---Try this experiment: put a dab of Brasso on a case that is trashed. let it sit for an hour, then remove the Brasso. You will see the brass is now redish. This is the copper showing on the brass that has lost zinc.

You have apparently used a minor amount of Brasso which has been diluted thru the media, and the ammonia has probably dissipated or evaporated, causing little damage to the brass. Compare the color of your used and Brasso’s brass with new. I would wager that it will be a slight bit on the coppery side compared to new.

Your are spinning the roulette wheel, and it will be only a matter of time before a case ruptures.

Sunray
April 19, 2007, 02:13 AM
You don't need any polishing compound. Brass needs to be clean, not shiny.

Walkalong
April 19, 2007, 07:18 AM
But we likes it shiney. :)

I have been using and like Frankford Arsenal (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=198878)polish. Berry's (http://www.berrysmfg.com/86.php) polish gets good reviews as well.

Navy_Guns
April 19, 2007, 08:01 AM
I learned recently NOT to use 800-mesh grinding compound powdered abrasive... It is too harsh and gives the cases a frosted look. It took several hours with walnut media and that Thumbler's red stuff to get them right.

I've got a lot of finer stuff (down to .05 micron alumina powder!) at my disposal but that Thumbler's works just fine.

P.S. Swiffer cloths work better than used dryer sheets!

cdrt
April 19, 2007, 09:18 AM
Thanks for all the replies. It appears from my experience with Brasso that it can be used safely if diluted in the media. I doubt if I am spinning the roulette wheel since I've been reloading and using Brasso since the 1970's and have never had a case "go brittle".
I can certainly see where actually polishing a case with Brasso might cause a failure of the brass, but who would do that. If a case is that bad, it should go in the trash.
And yes, I understand that the cases just need to be clean, but I have some cases that have been reloaded so many times, the Brasso helps at least make them look respectable when I reload them.
I checked the color of the cases and did not see any indication of any copper tint of the clean cases vs. the new ones that have never been cleaned, so the one post that suggested the ammonia had been diluted is probably correct.
I did pick up some brass at the range the other day that was really stained. To clean it, I used the old "distilled vinegar, salt, liquid dish soap' formula to see if it would work. It did a pretty credible job. Those cases went in the recyle bin since they were all odd ball mfg.

Again, thanks for all the comments.

Navy Vet & SWIFT Boat OIC

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