Polishing Brass

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Polishing Brass

Postby MochetVelo » Mon Nov 18, 2013 6:57 pm

After restoration comes the continuous task of polishing brass, the only alternative is lacquer or clear coat of some type. The "coated look" is OK, but not quite as nice visually as a freshly-polished surface. I can certainly understand why some collectors use it, however. The down-side of coatings is the chips and wear can look bad. As for polishing, there are several methods depending on how much corrosion you have. Here are my tips:

Horrible Corrosion

That is, sitting outdoors for 40 years. You'll make no progress with polishes or buffing. I suggest using a poultice made from equal parts flour, table salt and white vinegar. Smooze it on the bare (unlacquered) metal with your fingers and cover with a plastic bag overnight. Wipe off with a plastic putty knife, then water on a cloth. This treatment is safe and quite effective. To move up a notch in power, you can use Muriatic Acid, which is a 30% hydrochloric acid solution you get at the hardware store. Apply with an acid flux brush, protecting your eyes, skin and anything else that might get splashed. It's nasty, but acts almost instantaneously to remove corrosion. I like to use it on complex shapes and hardware. Wash with water immediately after use or your parts may dissolve!

Light Corrosion

Like a car you find on eBay; all the brass is a dull shade of brown. Here, a buffing wheel or polish may be enough to shine it up. Follow this procedure after the above treatment, also. If you prefer metal polish, you can start using it with 4/0 steel wool for more aggressive work followed by soft cloths. I suggest you not use ammonia-based polishes, as sheet brass can degrade with exposure to ammonia. A faster method is an electric buffer. You can buy a buffer motor with shafts (Baldor is the most popular). These rotate two buffing wheels at 1750 or 3450 RPM, though Caswell sells one that travels at 1100 RPM. I won't detail their use here, but you will use two grits of buffing compound. Wear leather gloves, and be prepared for the wheels to pull your object right out your hands (in other words, be careful). Keep the work moving, and clean the wheels. Use thinner and softer cloth wheels to get in-between objects. Finally, wipe with a clean cloth (or one dampened with mineral spirits).

Maintaining a Shine

This is where polish is usually used. Cover brass in the "off-season" with silver cloth, the soft treated cotton your rich aunt used in the silver chest. You can purchase this by the yard on eBay or buy ready-made covers at old-car places. There are many favorite polishes. For light work, I like Nev-R-Dull, a cotton wadding impregnated with a clear polish. What's nice about this is it leaves no white grit in crevices like other polishes. Another "clear" polish is Cape Cod Polishing cloths, vanilla-scented cotton cloths in a can. There are many more aggressive paste and liquid polishes available. No doubt you have a favorite. Some purport to leave a protective finish. Can you wax freshly-polished brass to protect the shine? Yes, but they wax must be stripped off when it builds up. It will wipe right off with paint thinner, however.

Be sure to post your tips and suggestions on the forum.

Phil
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Re: Polishing Brass

Postby Cadillac Bill » Mon Dec 18, 2017 5:18 am

Since this is 2013 post, are there any new tech polishes? Especially some that maintain the polish? Maybe a polish that cleans the brass, but leaves a slightly older appearance?
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Re: Polishing Brass

Postby MochetVelo » Mon Dec 18, 2017 5:59 am

Just forgo the lacquer/sealer after polishing, and you will get a nice patina in a few weeks. Here are a couple videos I did on removing heavy tarnish:

https://youtu.be/qQl-_qmuyeU

https://youtu.be/U-MkqJdPNDc

Phil
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