Cleaning a big sheet of badly tarnished brass

bfk

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At an estate sale last year I found a big chunk of tarnished brass. I think I spent about $70 on it. It's 36" square by 1/4" thick. It's heavy---took two of us to get it safely down the steep basement stairs.
It's also badly tarnished, as you can see.
I'd love to know what kind of brass it is, 260? 464? 280? Nowhere seems to have 360 in this size, so I don't think that's what it is. Is there a way to tell?

No idea what I'll do with it, but when I do, I think it would be nice if it didn't look like it had graced the bottom of the parrot cage for a decade.
Anyone have a great shortcut to get this clean? I do have a Cyclo polisher which will help if I know what to use on it.

IMG_2170.jpg
I know I can turn a profit taking it to the scrap yard, but I'd rather make something.
 
I would bead blast it with a fine media first.
 
I would bead blast it with a fine media first.
I wouldn't do that! Even with fine media, you risk a chance of it warping. If you do try it do a little on one side go to the opposite side and bead blast, and keep going back and forth until completely done. Amway used to have some cleaner that worked very good on stuff like this. Have no clue if they are around today.
 
you could make one heck of a lapping plate once you get it cleaned.

i wonder how phosphoric acid would react to brass???

you may test a small corner with phosphoric acid, your PPE, and a brass scrub brush- it may clean up nice
vinegar may also work.
 
Just get the liquid brasso and pour it on. 2 bottles will do one side.. then use some big rags to clean her up. Brasso does most of the work for you.
 
Tarn-X is one option

From the internet, author unknown.
"Heat a pint of water, and add 2 tablespoons each of salt and white vinegar to create another natural recipe for polishing tarnished brass. Rub the mixture onto the brass, then dry with a clean rag. Lemon Juice: Straight lemon juice can be used to clean brass and bring back shine."
 
Hydrochloric acid (muriatic acid) works very quickly on brass. Almost a wipe on/wipe off. Rinse thoroughly after cleaning and wipe dry.
 
I wouldn't worry about it at this point, I would clean it as I had a need for it. You might be machining most of it away anyhow. Tarnish makes for good visible scribed lines.
 
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