Info Articles

From Reddish Brown to Jade: How to Oxidize Copper

statue made of copper
Copper is widely known for many things. Most of us know it as the first metal discovered and used by man, preceding even gold and silver, yet strangely not as popular in ancient documents since it’s been utilized mostly for utilitarian applications. Because of the many useful properties of copper, major industries, such as transportation, construction, and telecommunication rely heavily on its production. As such, copper is also known as a barometer for the global economy, because its production reflects the current and future state of those industries.

In North America, we know copper as the material that make up many of our prominent landmarks, and one of the main reasons they still stand to this day. Best examples include the Library of Parliament in Ottawa, Ontario and the Massachusetts State House, which both have a copper roof. We also know that The Statue of Liberty in New York Harbor is also made mostly of copper. But a lot of us didn’t know that most of the old copper structures like The Statue of Liberty haven’t always been green. They were actually shiny, metallic-looking at first. The newly laid copper roof of the Massachusetts State House shows us a glimpse of how those structures used to look like.

But why did their color change? Have they been painted so they won’t rust like most steel structures? While coating the surface of metal certainly helps prevent corrosion, copper is different from other metals because it has its own way to protect itself from corrosion. In fact, the green color that it develops overtime is made up of a layer of patina, which serves as it shield.

What Is Patina?

Patina refers to the result of any aging process that causes discoloration or fading of a material’s natural color. The transformation of copper from shiny, reddish brown to green is actually the most popular type of patina formation. Bronze and brass undergo the same process, but that’s just because their main component is copper.

This aging process is generally known as oxidation. When a material, organic or inorganic, is exposed to oxygen, the oxygen molecules combine with the molecules that make up that material and create a chemical reaction. The kind of chemical reaction depends on the type of material involved. For instance, diced potatoes or fruits turn brown when exposed to the air. Iron rust in a moist environment. The oxidation that these materials undergo is actually a process of degradation, since it eats away at the material layer by layer until it’s reduced to dust.

Copper, on the other hand, experiences oxidation rather distinctly. Chemicals in its environment that make contact with its surface also cause reaction, but instead of breaking down on a molecular level overtime, it creates a layer of protection that prevents those chemicals from further digging into its core.

It’s important to note that oxidation isn’t always caused by oxygen. A lot of other elements and substances can cause the same reaction on metals. Quite many chemicals, apart from those that are naturally present in the air, can oxidize copper, including ammonium chloride crystals, copper sulfate and ammonium sulfate. These chemicals are used to bring out that uniquely elegant, greenish color of copper.

How to Oxidize Copper

When oxidized, copper can change into a shade of green, but not instantly. It normally takes many years of constant exposure to natural elements before that elegant, jadish green shade appears. In fact, you will see it transform into different shades of brown before it turns green. Fortunately, the oxidation process can be expedited so you can achieve the shade that you desire for your copper items. Here’s one way to force oxidize copper.

Most harsh substances are capable of oxidizing copper, but you don’t need to buy special acids just for that. Basic products like vinegar and salt can have the same effect. All you need is enough amount of these products to submerge your copper item for a certain period. So let’s say your item is just a piece of copper jewelry that you’d like to give a rustic, green appeal.

The first step is to thoroughly clean the jewelry to get rid of all traces of oil and dirt. After rinsing away all the suds, sprinkle a little bit of baking soda and scrub the surface of the jewelry with steel wool. That should remove any excess contaminants or coating stuck on the surface and allows the copper layer to be exposed to the oxidizing agent. Then wash off the baking soda without touching the jewelry with your skin.

Depending on the size of the jewelry, mix three parts of vinegar and three parts of salt well until you can no longer see salt crystals. Put the item into the mixture and let it soak for at least 30 minutes. After it’s fully soaked, take it out of the container and place it on a clean paper towel. Don’t wipe it; let it dry on its own. You can sprinkle a little bit of salt on its surface to further speed up oxidation.

Knowing simple ways to oxidize copper lets you stretch out your creativity. It can even open doors of opportunity for you in the craft industry. Nevertheless, don’t forget that it’s also important to get your copper supplies from a reputable supplier. Otherwise, the metal you will work with might not react correctly with the chemicals you will use. Top suppliers in North America such as Rotax Metals offer the highest quality supplies on the market. You might want to put them on your list.


Magnetism: What Metals Are Magnetic and What Are Not?

magnet picking metals in scrapyardEver wondered how scrapyards sort mountains of junk to separate the recyclables from the non-recyclables or to identify which materials are reusable for which applications? They use a variety of techniques from manual to machine-aided segregation since they are dealing with different types of materials.

One very effective technique that almost all big scrapyards use is magnetization. By holding up a powerful magnet above junk, iron-containing or “ferrous” metals can be extracted, leaving behind “non-ferrous” metals, such as copper, brass, and bronze. Of course, plastic items won’t be magnetized as well but they are easy to identify and separate.

How Magnetism Works

Humans have known about magnetism for thousands of years, and our understanding of it has given way to various forms of technology that support some of the most important industries of our time. Because the forces at work in magnetism are invisible, it can easily be mistaken for magic or supernatural occurrence. Unsurprisingly, a lot of magic tricks involve the use of magnetism due to its physics-defying features.Disappointingly for the superstitious, magnetism is pure science.

The best way to understand how magnetism works is by looking through the electron microscope and study the motion of electrons. An atom consists mainly of three types of elementary particles—protons and neutrons, which comprise the nucleus, and electrons, which orbit the nucleus and fill the atom’s orbitals.

Electrons normally come in pairs, both of which spin but in opposite directions. Electrons spin and movement across the atom’s orbital creates a magnetic field. Because a pair of electrons spin in opposite directions, they cancel each other out, eliminating their magnetic capability. Some atoms, however, have unpaired electrons that share the same orbitals. These electrons spin in the same direction, creating a force that either attracts or repels other atoms with unpaired electrons.

Types of Magnetism

Because a lot of different things can happen to the electrons of an atom when exposed to external forces, magnetism may occur in different ways as well. Here are some of the common types of magnetism that you may encounter when trying to magnetize different types of materials.

  • Diamagnetism

    – All materials have a natural tendency to oppose an applied magnetic field, except those that possess paramagnetic properties. This reaction to external magnetization is called diamagnetism.

  • Paramagnetism

    – Some materials have a tendency to enhance an external magnetic field and in the process cancel out their diamagnetic reaction. Each of their atoms have one unpaired electron that is free to align its magnetic moment in any direction where an applied magnetic field exists.

  • Ferromagnetism

    – Like paramagnetic materials, ferromagnetic materials have unpaired electrons on their orbitals. The only difference is that the intrinsic magnetic moment of these unpaired electrons also have the tendency to orient parallel to each other to maintain a low-energy state, allowing them to maintain magnetic force even in the absence of an applied field.

  • Antiferromagnetism

    – Obviously, this is the opposite of ferromagnetism. The intrinsic magnetic moment of the unpaired electrons tends to orient opposite each other instead of parallel to each other. As a result, they don’t create their own magnetic field and are completely reliant on applied field to generate magnetic attraction.

  • Ferrimagnetism

    – Some materials have qualities of both a ferromagnet (retaining magnetization in the absence of a magnetic field) and an antiferromagnet (sometimes rely on external magnetization). Magnetite, the first discovered magnetic substance and was originally believed to be a ferromagnet, is actually a ferrite.

Types of Magnet

Now that we understand how magnetism works on a subatomic level, we can conclude that some metals are naturally magnetic and that the magnetic properties of certain metals can be manipulated. This means not all metals are magnetic but can be alloyed with other metals to become one. Magnetic metals can be classified into three types:

  • Temporary Magnets

    – These are metals that become magnetized when exposed to a magnetic field and lose their magnetism when the magnetic field is removed.

  • Permanent Magnets

    – Some metals have natural magnetic properties. They can attract metals that exhibit the same type of magnetism as they do. Best examples include alnico (an alloy of aluminum, nickel, and cobalt) and ferrites (iron oxides combined with nickel, strontium, or cobalt).

  • Electromagnets

    – When you run an electrical current through a coil with a metal core, such as copper, you create a magnetic field, which disappears when the current is shut off.

Meanwhile, there are numerous applications involving the use of metal where magnetism isn’t necessary. Therefore, it is crucial to identify not just metals that can be magnetized, but also metals not attracted to magnets. Some of the most common types of metal attracted to magnets include iron, cobalt, nickel, and some alloys of rare earth metals.

Best examples of non-magnetic metals include copper and its alloys, such as bronze and brass. In fact, they are segregated from scrap by using magnetism to extract magnetic metals like iron mixed with them. Then again, copper is also a kind of metal used in magnets, particularly in electromagnets, due to its high electrical conductivity.

If you are planning to use metals in your project, it’s important to take note of what metals are magnetic and what are not. To be absolutely sure that you are picking the right materials, consult with experts like Rotax Metals. They can give you advice not only on the most ideal type of metal to use but also the exact grade and thickness.


Muntz Metal

What is Muntz Metal and Where is It Used in Our Everyday Lives?

Brass Cookware

The use of metals in everyday life is nothing new in human history. In fact, humans have been using metals since 5000 BC. Given this, it’s not surprising many people are familiar with common metals like copper, steel, bronze, and the like–but have you ever heard of Muntz metal?

Although Muntz metal isn’t a term that you come across very often, the use of Muntz metal is common throughout the modern world. Now, you might be thinking to yourself, “what is Muntz metal and where is it used? Before we dive into its uses and applications, however, let’s take a quick look at the history and composition of muntz metal.

What is Muntz Metal?

Muntz metal isn’t actually a unique type of metal per se. It is actually a type of brass alloy. If the typical brass you are familiar with is comprised of 67% copper and 33% zinc, Muntz metal is an alloy comprised of 60% copper, 40% zinc, and trace amounts of iron. The process of creating it is also quite unique since Muntz metal is manufactured by melting copper first and then introducing zinc and trace amounts of iron. This mixture is then placed into clay-line pans and then ladled into ingot molds.

George Fredrick Muntz, an English businessman from Birmingham, England, developed the metal in the 1830s, hence the metal’s name. This discovery was revolutionary at the time. Intercontinental travel during the 1800s was mostly done via large wood ships made of oak. Although wood is known to float on water (buoyancy), it was also susceptible to damage from shipworms. These worms had a nasty habit of burrowing into oak underbelly of large ships. From there, shipworms would slowly eat away the wood. As you can imagine, this presented a significant risk for seafarers and ship passengers, especially when travel between some countries could take months.  Muntz metal was seen as a solution to this problem.

Why Muntz Metal?

One of the key properties of Muntz metal was its anti-corrosive nature. Due to the specific mixture of different metals, Muntz metal was highly resistant to corrosion in the high seas. Naturally, the issue of shipworms became non-existent as the pests could not bore past the coat of Muntz metal covering ships. Shipworms weren’t the only pests that Muntz metal deterred. Barnacles are another common pest for seafaring vessels. Barnacles are notorious for clinging on to ships and, if there are a significant number of barnacles present, reducing the speed and efficiency of ships. Muntz metal helped solve these issues thanks to a neat chemical interaction with water. When exposed to water, Muntz metal diffuses a chemical that deters these pests from clinging to a ship.

The second reason why Muntz metal was a revolutionary invention at the time was its cost. You may have noticed that Muntz metal uses less copper than traditional brass. This resulted in a much lower mass manufacturing cost for manufacturers. In fact, Muntz metal carried a price tag that was two-thirds of the price of regular brass. This made it faster, easier, and more profitable to mass produce. The best part about Muntz metal for metalworkers and ship manufacturers was that the metal still retained the incredible durability associated with bronze. This meant ship builders received the same exceptional durability at a fraction of the price. It wasn’t long after its discovery that Muntz metal became commonplace in sea vessels worldwide.

What is Muntz Metal Used For?

Today, Muntz metal is still used for many maritime applications, despite the emergence of other similar metals like naval brass. Many shipbuilders still prefer to use Muntz metal for its cost-effective nature and incredible durability. Although only a few ships use Muntz metal as the protective layer of ships, the metal is still used in other applications on a ship, including fittings, pipes, and the like.

Muntz metal has also grown past its initial maritime use. Thanks to its brilliant gold color and corrosion resistance have attracted some furniture manufacturers to use the metal in their designs. Muntz metal is also sometimes used for residential pipes and plumbing since the chemical Muntz metal exudes when exposed to water has also been proven to inhibit the growth of bacteria.

Many of the bolts used in modern machinery are made of Muntz metal. This is mostly due to the price of the material, as well as the fact that Muntz metal can easily be fashioned into various shapes and sizes, making it ideal for manufacturing machinery parts.

Purchasing Muntz Metal

If you are interested in using Muntz metal for your next project, you’re definitely making a great choice. Durable, cost-efficient, and corrosion-resistant, Muntz metal is the perfect choice for a wide range of applications–but don’t buy Muntz metal from just anywhere. Stick to respected suppliers, like Rotax Metals, with decades of superior customer service. These suppliers are more likely to offer you high-quality Muntz metal, allowing you to enjoy all the advantages the material has to offer and giving you the best value for your money.


1 2 3 76

Product categories