How Long Does It Take for Brass to Rust?

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Nothing lasts forever. Metal has a pretty impressive life expectancy, though. Brass, like many other kinds of metal, can theoretically be recycled indefinitely without losing any of its structural properties. But that doesn't mean brass fixtures in your home will look pristine forever. Like iron, brass can change appearance over time if it's exposed to water or other corrosive elements. It's not a speedy process, though. It may take many years for brass to change colors even when it's used outdoors.

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Does Brass Rust?

In short, brass doesn't technically rust; it corrodes. The only metals that will form rust are those that contain iron, such as stainless steel. If you see metal with red or brown patches of pitted rust, you're looking at some kind of metal alloy made with iron. Rust occurs when iron is exposed to oxygen and water. Iron alloys can start to develop rust in less than a week when they're submerged in water.

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Both red brass and yellow brass are composed primarily of copper and zinc. (Red brass has more copper than yellow brass, hence its redder color and higher value than yellow brass.) Brass doesn't contain iron, so brass rust doesn't occur like steel rust. But like steel, brass's appearance can be changed by prolonged exposure to water and oxygen.

Brass and Dezincification

A process called dezincification can change the appearance of brass over time. When brass is exposed to water containing certain chemicals, an electrochemical reaction occurs that strips away some of the zinc in the metal. Because losing some of its zinc means brass has a higher concentration of copper, dezincification turns brass pinker. Mild cases only affect the appearance, but prolonged dezincification can create structural weakness in brass.

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Salt causes dezincification, so you may notice brass fixtures turning pink if they're exposed to salt water. For example, brass kick plates and fixtures on exterior doors may lose zinc if you live in a snowy place and use salt to deice walkways or if you live close to a body of salt water. You might see signs of dezincification on things that people touch often (like interior door knobs) because of the salts in sweat. Brass can also be intentionally dezincified by cleaning it with salt and vinegar.

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How long it takes for brass to show signs of dezincification depends entirely on how much exposure your brass has and how much zinc it contains.

Brass and Oxidation

Brass may also develop a greenish or brownish patina over time because of its high copper content. If you've seen the Statue of Liberty, you've seen copper oxidation in action. That green patina is a natural result of copper sulphate being exposed to oxygen and water in the environment.

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It generally takes many years for copper materials used outdoors to develop a patina; it took a few decades for the Statue of Liberty to turn green, even being constantly exposed to sea air. Brass fixtures may become tarnished even more slowly because they're not made of pure copper. But the process can also be sped up if you're trying to make shiny brass look antique by soaking brass pieces in an acidic bath of vinegar and salt.

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Cleaning Tarnished Brass

It can take years for brass to become tarnished and 30 minutes to restore its original shine if the corrosion is relatively minor. Brass items that have been weakened by dezincification or are completely covered with patina probably aren't going to look brand new when you're finished cleaning them.

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Brass fixtures and decorative items are often coated with a layer of protective coating, which you'll need to remove in order to get to the brass beneath. In many cases, removing lacquer from brass is as simple as boiling the items in water and baking soda.

Once lacquer is stripped away, use metal polish made for brass to clean tarnished pieces. Cleaning with this kind of polish is often as easy as spraying it on and wiping it off; no vigorous scrubbing is required. Use tarnish remover wipes to target any especially stubborn spots that do require a little extra elbow grease. Finally, apply a new layer of brass lacquer to protect brass from future corrosion.

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