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Rotax Metals

What Causes Brass to Corrode and How to Bring Back Its Lost Luster

Brass is one of the most underrated items on the global metal market. It possesses almost the same valuable properties as other prominent non-ferrous metals but doesn’t receive as much attention, let alone explored enough. Most people only know brass as a material for making musical instruments and have totally zero knowledge about its electrical, mechanical, and industrial uses. Perhaps it’s about time we learn more about this amazing metal so we can maximize its many potentials.

tarnished brass instrument

Copper and Zinc

To fully understand the amazing properties of brass, let’s first study its main components. Brass is made of about 85 percent copper and 15 percent zinc. Its modern versions contain more, including arsenic, lead, phosphorus, aluminum, manganese, and silicon, but let’s focus on its main components since they are the ones that give brass the majority of its unique qualities.

Copper is one of the oldest and most widely used metals on the planet. It may even be the very first metal to be discovered so its use dates back some 10,000 years ago. The reason why we know about this is because some artifacts from that period still exist today, and it’s interesting how a metal, which is known to be susceptible to corrosion, can survive that long. As it turns out, copper is not one of those metals with such weakness to corrosive substances. It creates its own shield, called patina, to protect its inner layers from deterioration.

Zinc, on the other hand, is a bluish white lustrous metal, which is brittle at room temperature but quite malleable at around at 100 to 150 degrees Celsius. Like copper, this metal also possesses exceptional resistance to corrosion, which is why it extensively used for galvanizing ferrous metals to prevent rusting.

Individually, copper and zinc are packed with valuable properties, so you can imagine what the result would be like if you combine them at an ideal proportion. Of the plethora of properties they share, though, the one that brass has acquired abundantly is corrosion resistance, and to this day, most applications that utilize brass require this unique property.

What causes brass to corrode?

The corrosion resistance of brass is well-known in the world of metallurgy. This is why it is commonly used for applications that involve exposure to water, moisture, and other corrosive substances. Its resistance to corrosion, however, can only do so much. It may not become as greenish brown as other copper-based metals when they corrode but brass can easily develop tarnish on its surface.

How does tarnish form? First of all, take note that tarnish is the first stage of the corrosion of non-ferrous metals. You will know if your brass item succumbs to tarnishing when its original sheen starts to haze up. If you let that dull, misty appearance of your brass item sit for too long, it will eventually thicken up until removing it to reveal the shiny surface underneath becomes almost impossible.

Tarnish in copper normally turns into a layer of copper dioxide almost immediately after being exposed to air. Over time, this copper dioxide further corrodes and gives up more oxygen to form copper oxide. Without maintenance for many years, this copper oxide develops into copper carbonate, which then serves as copper’s ultimate shield against the elements, and this is why it can last for millennia.

Unlike copper, brass doesn’t corrode that quickly. The tarnish on its surface, whether it’s a brass rod or a brass channel, may linger and not grow thicker for a long period. Although that’s a good thing about brass, its tarnish still doesn’t look pleasant and has to be fixed. Thankfully, tarnish is very easy to clean up. If you know what causes brass to tarnish, it’s wouldn’t be so hard to deal with. You don’t have to put up with your dull-looking brass furniture and fixtures that ruin the aesthetic of your home interior. You can polish and bring them back to their shiny selves.

How to Deal with Tarnished Brass

Polishing tarnished brass is not a simple task, but it’s not too complicated either. Be it a small item like a faucet valve or a large one like a stairway railing trim, you can polish it as effectively as you would your shoes. You don’t have to hire a professional to do it for you because you can pull it off on your own using the available products in your kitchen or garage. Apart from knowing what causes tarnish on brass, here are a few tips that can help you do a great job polishing your brasses.

  1. Wash the surface of your brass item with soap and water to remove any contaminants that may get in the way when you start scrubbing the item with cloth. All surfaces, even the grooves and crevices, must be free of dust and grime as they can pose some hazards on your item’s surface when they mix with your chosen polishing agent.
  2. Rinse the newly washed item thoroughly to remove the lather and dislodged dirt from its surface. Any foreign material left could potentially affect the effectiveness of the cleaning process. Then wipe with a clean cloth before letting the item dry completely. You can sun dry it but don’t leave it outside for too long so the surface won’t burn up.
  3. Choose between commercial polishing products and natural products. There are scores of ready-made polishing products available in your local hardware store, but check their concentrations carefully so you won’t mistakenly buy one that’s too harsh for your brass item. Sometimes, especially if you are dealing with flimsy plates or tiny rods, it’s much safer to use natural products, such as ketchup, vinegar, and baking soda. All of these have just enough acerbity to melt away tarnish without scuffing your brass item.
  4. Once fully buffed, seal the surface of your brass item with a clear lacquer to preserve its sheen for a long time. This way you won’t have to clean and polish your brass item too quickly.

While these tips can surely help preserve the beauty of your brass items, there’s one way to actually avoid or at least delay the need to do them at all. That is simply to look for items that are made from high-quality brass. You have to understand that brass products come in different qualities because they are made by different manufacturers.

In case you are looking for brass supplies for construction or craft, make sure that the supplies you will purchase come from any of the established brass suppliers in North America like Rotax Metals. This way you can be sure that your materials are manufactured in the best foundry and had passed all necessary quality tests before being distributed to local markets.

Causes of Corrosion and Effective Ways to Clean Metal

Metals have the reputation of being the strongest material on Earth. There are not very many materials that can rival their strength. The only materials that can are the pure carbons, which are not as abundant and lack the necessary properties to resist breakage.

metal nuts and bolts

That being said, metals are not indestructible. Like everything else, they have a weakness, too. Specifically, they are not very good with a variety of liquids and acids, and sometimes other metals. When exposed to even a tiny drop of these substances, they will start corroding. The manner by which metals corrode depend on certain factors, including their composition and properties as well as the type of substance they are exposed to.

Types of Corrosion

Corrosion can be likened to a virus. It attacks the metal slowly until the metal is reduced to dust (a state where the molecules are completely disintegrated). It’s extremely important to understand how metal corrodes and where it corrodes from in order to come up with an effective solution to strengthen metal’s resistance. Here are some of the types of corrosion that we know of.

  • Uniform Attack.

    The metal’s chemical or electrochemical reaction takes place consistently over its entire surface, causing it to become thinner or smaller over time. For instance, a piece of iron plate suffers the same degree of rusting on its whole surface.

  • Galvanic Corrosion.

    Some metals are allergic to other metals. When immersed in a conductive solution, the potential difference of two different metals gets activated. This becomes dangerous for any or both of the metals when they are placed in contact with each other. The less resistant metal usually becomes even weaker to corrosion during this process, while the more resistant one becomes even more resistant.

  • Crevice Corrosion.

    This type of corrosion happens when not all of the surface of a certain metal is protected or if there are holes, gasket surfaces, lap joints, surface deposits, and crevices, hence the name. Attack only occurs on the region that is exposed, leading to an intense localized corrosion.

  • Pitting.

    Considered as one of the most destructive forms of corrosion, pitting comes in the form of holes, which range in size from tiny, almost invisible to large cavity. In fact, most pits are too small they appear like a rough surface, when in fact they extend to a few millimeters into the metal surface, making them more detrimental than they appear.

  • Selective Leaching.

    Sometimes, corrosion only attacks specific metals. This can be troublesome if the metal it attacks is alloyed to another metal. When that happens the metal in question is selectively leached out from the alloy, leaving only a porous block made solely of the resistant metal, rendering it totally useless.

Dealing with Oxygen

While there are literally countless types of liquid that can potentially corrode metal, there’s one liquid that stands out as the most dreaded of all—water. It may not be as corrosive as most acids but its abundance is what makes it so vile. Whether it’s in the form of liquid or vapor, its impact on metals remains the same.

Technically, it’s not water that triggers the corrosion of metal, but the oxygen it contains, and different metals react to oxidation differently. Metals that contain iron, also known as ferrous metals, are the most reactive. The oxygen in water or moisture latches to iron to form iron oxide or rust.

This type of corrosion prompted by oxidation can be prevented or weakened using a number of methods. The most popular method is alloying iron with non-ferrous metals the exhibit anti-corrosive properties or non-metals that have the ability to repel oxygen. In the case of iron, a controlled amount of carbon is added to give it oxygen-repelling property, which forms steel as a result. Other metals, such as molybdenum and manganese are sometimes combined with steel to increase its corrosion resistance.

Oxidation of Non-Ferrous Metals

Unsurprisingly, iron or iron-containing alloys are not the only ones that react to oxidation in the form of corrosion. Some non-ferrous metals do, too, but in a completely different way. Instead of combining with every atom that makes up the material, oxygen only combines with the atom on the surface and grows thicker from there.

The best example of metals that react this way are copper and all its alloys. When copper makes contact with oxygen molecules from the air, it forms copper dioxide, but it stops on the surface. It doesn’t spread within the material. Instead, the copper dioxide that is now covering the exposed surface of copper reacts with oxygen to form copper oxide, and that becomes the thick greenish layer that protects copper from wear and further corrosion.

Good and Bad Things about Corrosion of Non-Ferrous Metals

Corrosion, generally, is considered a bad thing, because it destroys metals that could otherwise last for long or perform optimally throughout its functional life. For non-ferrous metals, however, corrosion is viewed quite differently, mainly because it doesn’t really affect their main properties. In fact, some find the result of the corrosion appealing, so much so that they even facilitate its occurrence. They think such characteristic produces an antique vibe that makes a great addition to a building’s aesthetics.

Then again, most people want their metal shiny. Sheen, after all, matches with all kinds of interior design. For industrial applications, a metal’s surface must be free from any kinds of corrosion to maximize its mechanical properties as well. Unfortunately, common non-ferrous metals, such as copper, brass, and bronze are very quick to tarnish when exposed to air. Fortunately, though, there are easy and effective ways to clean metal that even non-professionals can try.

Cleaning Tips for Metal

It may seem hard to remove but the tarnish, or even the patina, on your brass or bronze bars and plates is quite yielding. In fact, you can do so using everyday items found in your home. Of course, there are commercial metal polishing products that are available in your local hardware or furniture store when you prefer a better finish.

  1. Some of the products you can use to naturally clean your copper items include vinegar, ketchup, lemon, and baking soda. Before you apply any of them on the surface of your brass or bronze item, however, make certain that the item is thoroughly cleaned with no excess dirt or grime that can leave scratches after burnishing.
  2. Once the item is clean, apply as much of your chosen polishing agent as needed on its surface. Do this with your hand first to dislodge left-over stains and patina that weren’t removed during initial cleaning. Then wipe away excess polishing agent and let the remaining layer dry up a bit. Once dry, start scrubbing and buffing the surface of the item with a clean white cloth until the shiny surface reappears.
  3. To preserve the metal’s sheen after polishing, consider spraying with a clear lacquer. This is available in your local hardware store as well. The lacquer, however, is also prone to wear and tear so expect that it will thin out over time until the metal’s surface is exposed to the atmosphere again. Your best option is to just have to clean and polish the item regularly to preserve its pristine appearance.

That’s pretty much the basic method for cleaning metal. If you still want to know more about what to use to clean metal, particularly copper-based ones, you can always consult with bronze and brass suppliers like Rotax Metals. They sure know their way around metals and how to prolong their valuable properties.

What Are the Advantages of Brass?

Brass is one of the oldest metal alloys in existence. An alloy of copper and zinc, this metal is prized for its many valuable properties, which suited a great deal of applications even in prehistory. Development of brass, however, only took place until the post medieval period because it’s only during then when metallurgists realized that the zinc vapor that makes the production of brass possible is actually a different kind of metal and not just a gas.

brass screws

During the time when brass had no exact classification yet, it is often used to refer to any type of bronze given that copper is also its base metal. It soon became clear that brass is an entirely different metal from bronze due to its distinct qualities. It has bright and lustrous yellow color that makes it look like gold, something you won’t see in bronze. It’s also harder yet more malleable than bronze.

Classifications of Brass

Like other alloys of copper, brass may come in a range of versions since its content can be manipulated. Each version exhibits a different set of properties, which is also why the benefits of using brass may vary. To avoid confusion and ease manufacturing, metallurgists came up with the brilliant idea to classify brass. They were grouped according to the amount of zinc or copper they contain. Those with higher copper content have better quality and are more expensive.

  • Alpha.

    These are brasses that contain less than 37 percent zinc. Because zinc in these versions of brass only comes in small quantities, it easily dissolves into copper, which results in a uniform distribution of zinc atoms across the sea of copper molecules. The result is often a high-quality brass that is easy to cold work, weld, roll, draw, bend or braze. With more copper in its content, alpha brasses are the most corrosion resistant among the brass classes.

  • Alpha-Beta.

    These brasses are a little bit tougher and less ductile or malleable than alpha brasses because they contain more zinc, specifically between 37 and 45 percent. That’s almost a 50-50 ratio with copper. One distinct characteristic of alpha-beta brasses is its almost dominant beta structure. Meaning, its grains look almost similar to pure brass. The quality, though, remains fine. To compensate for the valuable quality brass loses due to addition of more zinc, a miniscule amount of other metals, such as aluminum, silicon, or tin is added.

  • Beta.

    Brasses with more than 45 percent zinc are classified as beta brasses. These are the least popular types of brass. They are too hard to be cold worked so only hot working is applicable. Due to their high zinc content, beta brasses are susceptible to dezincification, a type of corrosion that leaches zinc from the brass, leaving a porous block of copper material.

Popular Types of Brass

After many years of exploring the properties of brass, over 20 different types of brass have been created, each of which has benefited an industry or two. Here are some of the most popular of them.

  • Admiralty Brass.

    This alpha-beta brass has only 30 percent zinc, making it extremely resistant to corrosion. A miniscule amount of tin is added to increase its resistance to dezincification. Admiralty brass is the metal of choice for manufacturing tubes for coolers and evaporators as well as surface plates for desalination plants.

  • Aluminum Brass.

    This type of brass has 77 percent copper, 20 percent zinc, and 2 percent aluminum. The presence of aluminum makes this brass extremely resistant to many kinds of corrosion. It’s no wonder aluminum brass is often used for applications that involve extreme heat and moisture, such as heat exchangers and condensers.

  • Cartridge Brass.

    The name of this brass type was derived from its main purpose, which is for making ammunition cartridges. Cartridge brasses, together with common brasses, are the most popular types of brasses available. They contain about 70 percent copper and 30 percent zinc, the standard requirement for an alpha classification.

  • High Brass.

    The “high” in the name of this brass type refers to the bass’s high tensile strength. Having 65 percent copper and 35 percent zinc, high brass has just enough softness and hardness to withstand powerful tensions. This is why this brass type is preferred for making bolts, screws, and rivets.

  • Gilding Metal.

    Of all the existing versions of brass, this is the softest, containing a staggering 95 percent copper and only 5 percent zinc. This makes the metal look almost like pure copper—reddish and supple.

  • Leaded Brass.

    Manufacturers in the electronic and industrial field are in constant hunt for metals that have high machinability. Luckily, they found that adding lead to brass makes the latter easy to cut with a satisfactory finish.

  • Naval Brass.

    Like admiralty brass, naval brass possesses an extremely high corrosion resistance, allowing it to withstand even long exposures to saltwater, which is known to be ten times more corrosive than fresh water. This makes naval brass the perfect choice for most marine applications.

Advantages of Brass

The great variety of commercially available brasses is proof that they are highly in demand across many industries and that’s all thanks to their plethora of beneficial properties. Here are some of the brass benefits you should know before you use brass supplies for any of your projects:

  • Durability.

    Both copper and zinc are non-ferrous metals, and the other elements that are added to the alloy are mostly non-ferrous as well. It’s only natural that the resulting alloy when they are combined is also unsusceptible to corrosion via oxidation. Even though brass tarnishes easily, this only affects its luster and not its performance and durability.

  • Anti-Bacterial Property.

    The molecules of copper in brass are capable of producing ions that attack a certain type of protein in single-celled organisms, killing them instantly in the process. This makes brass and other copper-based metals for that matter an excellent material for water filtration and sanitation systems. They are even suitable for lavatories, kitchen sinks, and other areas in the house that provide breeding ground for harmful microbes.

  • Aesthetics.

    Unlike pure copper and bronze, brass has a quite attractive appearance. Its natural color is very similar to that of gold, which is why it is often used as accessories and decorative element for buildings.

When looking for brass supplies, you need to know these important facts so that you can pick the right items and find the right supplier. It’s always advisable to find a metal supplier that specializes in copper-based products because they, more than any other store, know everything about brass, including all grades and manner of manufacturing. Reputable suppliers like Rotax Metals, which have many decades of experience, are your best option for a brass and copper sheet supplier.

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