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Brass is an alloy of copper and zinc. Due to its versatility and fair corrosion resistance, brass finds extensive use in decorative and architectural applications. One question we have been getting all week is, Does brass alloy rust? Whether you’re a student or a blacksmith, you’re in luck. This article teaches you why brass does not rust. We also uncover the differences between iron rust, brass tarnish, and brass corrosion.
What Is Rust and Why Brass Doesn’t Rust
Brass is an alloy of copper and zinc, and technically, it does not rust. Only metals that contain iron can rust. When iron is exposed to air or moisture, iron oxide forms, producing rust. Iron alloys may even develop rust in less than a week after being submerged in water.
Tarnish and Corrosion in Brass
While brass is immune to rust, it still undergoes different forms of degradation. Let’s use this section to learn about brass corrosion and tarnishing.
Does Brass Tarnish?
When brass reacts with oxygen, it continuously forms copper oxide, which produces tarnish. Tarnish is a layer of corrosion that causes the brass surface to turn brown or black. It is also the first stage of corrosion in non-ferrous metals. However, unlike rust, tarnish is not a sign of metal damage. Instead, it is a protective shield that prevents further corrosion.
Does Brass Corrode?
When metal degrades due to electrochemical or chemical reactions, it is said to have corroded. For brass alloy, there are three prevalent forms of corrosion. Number one is tarnish, which, as we just learned, functions as a protective barrier. The other two are verdigris and dezincification:
- Dezincification
Dezincification is a type of corrosion that strips brass of zinc, leaving behind a copper-rich material. Dezincification mostly occurs in seawater and harsh marine environments, and it can cause sudden failure of your application. For better understanding, refer to the complete guide on dezincification.
- Verdigris
Verdigris is a bluish-green patina that forms when brass is exposed to air for a long time.
Difference Between Rust, Tarnish, and Corrosion in Brass
If you are just getting your feet wet in material science, it is easy to confuse rust with tarnish. However, they are not the same thing. Rust refers to iron oxide, a compound that causes iron alloys to weaken. Since regular brass contains no iron, it cannot rust. Corrosion, in contrast, is when metals degrade due to environmental conditions. Brass corrosion encompasses tarnish, dezincification, and verdigris.
Environmental Factors Affecting Brass
Here is how different environmental conditions affect brass corrosion.
Moisture and Humidity
Moisture speeds up the corrosion rate of brass. The high levels of vapor in the environment create a perfect ground for electrochemical reactions to occur. This makes your brass object corrode faster.
Saltwater and Marine Environments
Marine environments are another risk factor for brass corrosion. Although brass offers fair corrosion properties, the chlorides in seawater can cause rapid dezincification.
Chemicals (ammonia, acids, chlorides)
Apart from marine environments, pollutants can greatly affect brass’s corrosion properties. Ammonia is a good example of these pollutants. It attacks brass under stress and causes sudden mechanical failure. Acids and industrial chemicals can also increase corrosion rates by breaking down the copper-rich layer of brass.
Outdoor vs Indoor Use
Outdoor brass instruments withstand constant exposure to UV rays from the sun, air pollutants, and rain. These factors increase the rate of tarnish, dezincification, and verdigris formation.
In contrast, indoor brass objects generally exhibit slower corrosion because the environment is more stable.
Common Signs of Corroded Brass
Some signs of brass corrosion include
Dull brown tarnish layer:
Tarnish is the first visible sign of brass corrosion. Look out for a brown or black layer that dulls the brass’s appearance.
Green/blue verdigris deposits:
In the brass corrosion lifecycle, tarnish eventually transforms into greenish patina or verdigris deposits
Pitting or weakened surfaces in severe cases:
Lastly, regularly inspect your brass instruments for pitting, corrosion, or weak surfaces that may be prone to sudden failure.
Is Brass Waterproof?
Brass is water-resistant but not waterproof. The term waterproof is reserved for metals that withstand frequent water exposure without corroding or losing their appearance. However, as we learnt earlier, humidity and prolonged saltwater exposure can increase the rate of brass corrosion. That said, brass’s water-resistance properties make it suitable for many marine and plumbing environments. These range from plumbing fittings to boat propellers and more.
Preventing Brass Tarnish and Corrosion
Here are the best practices for preventing the corrosion of brass.
Regular Cleaning and Polishing
Keeping your brass clean and dust-free is the most effective means to prevent corrosion. Prepare a mild soap solution and warm water, then gently move a cloth in the direction of the buildup. Do your best to handle the metal with gloves. And after the cleaning procedure, thoroughly rinse the brass of cleaning solutions, as they contain acids that speed up verdigris.
Protective Coatings
Brass coating offers an extra layer of protection against corrosion. You can apply polymers, oil, or waxes to the surface of your brass. Just note that they must be reapplied occasionally, since they wear off over time.
Proper Storage
Brass tarnishing can worsen when the object is exposed to excessive sunlight. Hence, metal experts recommend sealing brass appliances in airtight containers.
Routine Maintenance
Routine inspections and maintenance can help reduce the risk of brass corrosion. First, ensure you clean the item frequently. Next, polish it to restore its golden hue. Then apply protective coatings to extend the lifespan of the brass object. If you want to learn more, check the article on routine brass maintenance.
Applications of Brass and Why It’s Preferred
In the previous section, you discovered best practices for increasing the lifespan of your brass appliances. In this section, you will learn about the applications of brass across multiple industries.
Musical instruments:
Trumpets, tubas, or horns are commonly made from brass.
Plumbing and water fittings:
You can use brass alloys to produce plumbing fittings, faucets, and pipes. Brass is also preferred in heat sinks and exchangers thanks to its fair thermal conductivity.
Decorative items and jewelry:
Brass is one of the most widely used metals in jewellery manufacturing. It closely resembles gold while being nowhere near as expensive.
Marine and outdoor hardware:
You can use marine-grade brass to manufacture marine hardware. Common examples are fittings, propellers, and bearings.
Conclusion
To sum up, only metals that contain iron can rust. Therefore, brass alloy, which is made up of copper and zinc, cannot rust. If you are evaluating the best anti-rust metals for your next project, look no further than HRC Precision manufacturing. Our experts at HRC are glad to support you on any technical matters!
FAQs
Does water cause brass to rust?
Brass cannot rust in water since it contains no iron. However, brass that is exposed to moisture will build up a protective layer of tarnish.
Will brass corrode outdoors?
Over time, outdoor brass appliances will form a layer of patina. As you learned earlier, this patina serves as a shield, protecting the brass against corrosion.
How do I remove green corrosion from brass?
If you want to remove green verdigris from brass, apply a commercial brass cleaner to the affected regions. Alternatively, you can mix equal parts vinegar, salt, and flour, then apply it to the brass. After about an hour, wipe it off with a clean cloth and then rinse your brass object thoroughly.
Is brass more corrosion-resistant than steel?
Pure brass is more corrosion-resistant than steel. However, steels that have been enhanced with chromium or copper might be superior to brass in terms of atmospheric resistance.
