Copyright 2010 – Kimberly Clay
Restoring and cleaning antique brass without damaging it is a skill that can be learned, but get it wrong and your brass pieces can lose their value very rapidly. First, however, you have to be sure it is brass, so how to you do that?
Is It Genuine Brass?
Genuine brass is an alloy of copper and zinc, generally 67% copper and 33% zinc. The other alloy some confuse it with is the harder and less malleable bronze, which is an alloy of copper and tin. Some alleged brass items are actually zinc or a ferrous metal coated with an antique brass finish – a form of brass paint. This is a popular finish for articles such as door handles and faux brass candlesticks intended for decoration.
The color is the same as that of brass, and the coating can be designed to replicate the appearance of old brass. It can also be varnished to give it a shine. Imagine a bowl, for example, pressed from plate iron or steel, perhaps hammered with the ball end of a hammer, and then polished and coated with a transparent yellow lacquer. That would look just like brass. The obvious way to test that would be to scrape it and determine if the lacquer or paint scrapes off – but use an inconspicuous part of the item because if the brass is genuine you would likely damage it!
A better test to tell genuine antique brass from coated ferrous metals or zinc is to try a magnet on it. A magnet will not stick to genuine brass. You should also be suspicious if it is too bright and shiny because genuine antique brass tends to be dark and dull. It wears over time, and the copper oxidizes to turn it a darkish color.
Is it Lacquered?
It is unlikely for badly maintained antique brass to be of a very shiny yellow color, and it certainly won’t have a clear lacquer protecting it as much of the modern brass you find today has. However, if the brass has been recently cleaned then it could look a bright shiny yellow color, and might also have been lacquered for protection. Nevertheless, lacquer is not a good sign on alleged antique brass pieces.
You can normally tell a virgin clean brass surface from a lacquered surface if you look closely enough. There is visible difference between a polished metal surface and one coated with clear gloss lacquer. You could also try scraping the lacquer off from an inconspicuous part of the item.
Cleaning Antique Brass
Restoring and cleaning antique brass generally involves removing dirt and oxidation and then protecting it from further oxidation. If your brass has been neglected for years, then first steep it in undiluted household ammonia or acetic acid (vinegar) for an hour. Caustic ammonia will attack the oxidation, dirt and grime – and also the metal, so that any light engraving might be reduced or even lost!
However, although acids will attack mainly the tarnish, it does so effectively and an acid such as vinegar or lemon juice might be better for heavy oxidation or tarnishing. Light tarnishing would respond well to ammonia that also removes dirt, and is contained in many commercial metal polishes. For a natural cleaning method, simply cut a lemon in half and sprinkle some salt on it to offer some abrasive power and then rub that on the brass. You could also sprinkle some vinegar over the lemon to get the power of both. Don’t hold back because you won’t damage brass by rubbing hard.
Worcester sauce or tomato ketchup are also effective brass cleaners, but if your brass has been lacquered then you will have to remove it first.
Removing Lacquer from Antique Brass
Antique brass should not be lacquered, but if it is then the lacquer can be removed in a number of ways. First, heat up some water until you can just bear it on your hands and then pour it over the piece. If the lacquer is thin you should be able to peel it off while it is hot. Failing that, try nail polish remover (acetone) which should be effective, or methylated spirit (denatured alcohol). Most lacquers are based on acetone or alcohol-soluble resins.
Using Brasso and Other Metal Polishes in Cleaning Antique Brass
Commercial brass cleaners such as Brasso can also be used rather than the natural cleaners mentioned above. There is nothing wrong with such metal polishes, but they tend to leave whitish residue of silica in indentations, round copper rivets and in fine engraving. If you only have a flat surface to clean, with no area that can collect the dried silica, then Brasso is fine.
It contains ammonia and also hydrocarbons to dissolve grease and dirt. Some forms contain alcohol and oxalic acid, so Brasso basically contains many of the cleaning agents recommended above. The silica is there as an abrasive agent rather than the salt that can also be used. Those that profess such cleaners to be damaging to the metal are partially wrong because it is no more damaging than any other cleaner – it is just the residue that it leaves if not cleaned off properly that is the problem.
Maintenance of Antique Brass
After you have cleaned your brass, simply leave it. Do not keep cleaning it whenever it loses its shine because you are liable to leach the copper out to the top, and that will then be oxidized to the greenish color (verdigris) of copper oxide that most pure copper items revert to when left open to the air.
You could lacquer it, although it can look a bit false, but many love the patination that genuine antique brass takes on as it ages. Nevertheless, a light spraying of lacquer can go part way towards to complete protection and the natural look. You could also spray or coat it with a light coating of wax to keep out the air (oxygen) that causes the tarnish, but that is also easily removed.
By taking care when restoring and cleaning antique brass you will maintain its lovely rich warm color and protect it from the oxidation that is responsible for the tarnish.
A last and important warning: If you have antique brass that you have collected for the purpose of investment, it is strongly recommended that you do not clean the brass finish. Any removal of the patination is considered undesirable to collectors. It is the same as removing the finish of 200 year-old furniture – you just wouldn’t do it. Removing the aged finish can greatly devalue your antique.
We invite you to shop for antique brass in central Kentucky!