Copper Patina | How to Patina Copper | Patina Color (2023)

The Science of How Copper Forms Patina

Copper home furnishings provide an elegant beauty because copper is a “living” metal, meaning it changes color over time. The beauty of copper is unique among decorative materials because the changes it undergoes are unique to each home and location.

The natural changes that happen to copper objects make them a one-of-a-kind symbol of heritage that's hard to replicate. The shades of patina that form on the surface of a copper furnishing can store the memories of meals, spills, new homes and life changes over the course of centuries.

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Copper is more than a shiny metal — it is one that can be adorned with beautiful carvings that tell a story. Knowing how copper patina forms will give you a deeper appreciation for the unique patina that appears in your family's history. This knowledge will also allow you to influence what color of patina forms, and how fast it will do so.

The Chemical Reaction

Ever ask yourself, “Why does copper turn green?” The formation of patina on copper is similar to the formation of rust on iron. Both happen when oxygen in the air interacts with the metal atoms in the presence of water.

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Copper reacts with oxygen that is in the air, resulting in copper dioxide (Equation 1). The copper dioxide then reacts with more oxygen to form copper oxide (Equation 2). This copper oxide from reaction 2 is the main culprit that will later form the colors of the patina. If sulfur is present on the surface of the copper, then the two can react to form copper sulfide, which is black (Equation 3). The greenish and blueish colors of copper’s patina come from the next set of reactions.

Air contains more than just the oxygen that we breathe. It contains carbon dioxide, which we breathe out, along with water vapor.

The first reaction that gives patina its color is when one molecule of carbon dioxide and one molecule of water, both in the air, react with two molecules of copper oxide on the surface of the copper. The result is a compound called malachite (Equation 4), which varies in color from shades of dark green to shades of blue.

The second reaction that adds to patina’s color is when three molecules of copper oxide from Equation 2 can react with two molecules of carbon dioxide and one molecule of water (Equation 5). The result is azurite, which is a compound that varies in color from shades of blue to shades of purple.

The third reaction that influences the color of patina is when four molecules of copper oxide from Equation 2 reacts with one sulfate molecule and three water molecules (Equation 6). The result is a compound called brochantite, which varies in color from shades of dark green to emerald.

The chemical reactions described above can be written in atomic symbols as follows:

  • Equation 1: 4Cu + O2 → 2Cu2O [red to pink]
  • Equation 2: 2Cu2O + O2 → 4CuO [black]
  • Equation 3: Cu + S → CuS [black]
  • Equation 4: 2CuO + CO2 + H2O → Cu2CO3(OH)2 [“malachite,” dark green to blue]
  • Equation 5: 3CuO + 2CO2 + H2O → Cu3(CO3)2(OH)2 [“azurite,” blue to purple]
  • Equation 6: 4CuO + SO3 + 3H2O → Cu4SO4(OH)6 [“brochantite,” dark green to emerald]

Reasons Why Patina Can Be Green and Blue

Patina has different colors and patterns that depend on the unique experience that each copper object has had. The next section explains the physics and chemistry of why the colors of patina can vary so much from place to place and from time to time. This section describes in broad terms why the presence of certain chemical compounds can affect the green and blue hues often seen in patina.

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The products that result from Equations 4-6 in the previous section each has their own shades of color:

  • Malachite: dark green to blue
  • Azurite: blue to purple
  • Brochantite: dark green to emerald

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Depending on what combination of these three is present, the color of the patina can vary from shades of green to shades of blue. Darker greens indicate an abundance of malachite and brochantite, while blues suggest that azurite is abundant. Each of these three compounds can form beautiful crystalline structures on their own, like precious rocks. When mixed in small amounts and held on the surface of copper, these three compounds produce the pleasant luster of patina.

(Video) Copper Patinas - How To Patina Copper Metal - Five Recipes - Verdigris, Liver of Sulphur, Vinegar

It is interesting to note that human blood is red because the molecule that carries oxygen in our blood is iron, which produces a red color. Shellfish, such as crabs, have greenish-blue blood because the metal atom that carries oxygen in their bodies is copper.

Factors That Affect Patina Formation

Why does copper patina over time? As we have established, patina forms on copper because of chemical reactions. The faster a chemical reaction is, the more products will form. Several factors in the copper and the surrounding environment can affect how fast patina forms, and what colors it will have.

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Knowing these factors will not only help you appreciate the patina on your copper but will also allow you to influence how the patina forms. This knowledge will surely impress your friends and relatives as they marvel at the elegance of your copper and the sophistication it brings to both your home and your conversations.


Chemical reactions happen when molecules move and collide with each other. The molecules are too small to see with the naked eye, but we know that chemical reactions happen thanks to a variety of signs, such as a change in color. Heat causes molecules to move faster, whether those molecules are bouncing around in the air or a liquid. Higher temperatures cause more reactions to happen at the surface of the copper.

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The higher the temperature, the faster chemical reactions can occur. Faster-moving molecules move with more energy, so their collisions with each other are more likely to break connections within a molecule. More than that, high-energy collisions help to form bonds between two molecules. This is similar to how it is easier to dissolve sugar in hot tea than it is to do so in iced tea. Ever wonder why the sugar always sits at the bottom of your iced tea, even though you have been stirring it for five minutes?

Geographic Location

Different regions have different climates. Inland and desert areas can be very hot, while coastal regions are cold. Regions at high elevations are colder than valleys. Often the location where you keep your copper products determines the temperatures that your copper is exposed to.

Room Ventilation and Nearby Sources of Heat

Rooms without windows and ventilation can become very hot during the summer. Stoves, fireplaces, furnaces, heaters and refrigerators produce heat. This heat can warm up the entire room or nearby copper objects.

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Humidity & Precipitation

The chemical reactions that form patina require the presence of water. Water exists in the form of moisture in the air, mist, rain, and snow. Some places have high humidity, meaning there is a lot of moisture in the air. Some regions have both high temperatures and high humidity, which promotes the chemical reactions that form the patina. Some regions are very dry, so there is minimal natural water vapor in the air.

Precipitation Rate

Different regions receive different amounts of rain and snow. Copper objects exposed to wet weather are frequently drenched or moist. Some regions have rain for most of the year, while others receive only a few weeks of rain per year.

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Nearby Sources of Steam

Household appliances can produce steam, which moistens the air. Kettles, water boilers, and pressure cookers release significant amounts of steam that can affect nearby copper objects or ones in the same room.

Impurities in the Copper

Copper ore taken from the ground has many impurities in it. Through the process of electrolysis, pure copper is obtained. However, copper can contain impurities in the form of other metals, such as iron, nickel, cobalt and molybdenum. These impurities can also react with oxygen and water vapor, just like copper does, to form compounds that have color.

Iron can form iron oxides that have a reddish brown color. Cobalt can form cobalt oxides that have a greenish-brown color. The amount of impurities in the copper can affect the color of the patina.

Air Pollution

In Equation 6 above, copper oxide reacts with sulfur oxide and water to form brochantite, which gives a greenish color to patina. Sulfur exists in the atmosphere in the form of sulfur oxide. One source of sulfur oxide air pollution is through burning fossil fuels, such as oil and gasoline. In fact, acidic rain that damages buildings and statues gets its acidity in part from the sulfur oxides that mix with water vapor to form sulfuric acid. Urban areas that have many automobiles will have high amounts of sulfur oxides in the atmosphere. Other sources of sulfur oxide production in the air are industrial regions that release smoke, such as power plants and chemical production plants.

(Video) How to Patina Copper

Copper Patinas in Action

Now that we’ve looked at the science behind copper patinas, what are some examples of this design element in action? Once you’ve learned how to recognize its distinct green appearance, you may be surprised at how common it is. Copper has been a key architectural material throughout history.

The Statue of Liberty might be the most famous copper patina in the world. It’s hard to imagine that it was brown when it was first assembled! Here are a few more buildings that feature copper patinas in various shades of green:

Berlin Cathedral

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The Berlin Cathedral is one of the most recognizable buildings in Berlin. It was built between 1894 and 1905, and features five copper domes and multiple copper statues. Although it was damaged in World War II, it has since been restored, and retains its iconic green patina.

Nordic Embassies, Berlin

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Also located in Berlin, the Nordic Embassies are another unique example of copper in architecture, this time with a distinctly modern appearance. It contains buildings representing each of the Nordic Countries, surrounded by a green copper wall that winds its way around the complex. According to its architect, “the copper strip is a sequence of 3,850 copper lamellas of the same type.” Completed in 1999, the wall provides a cohesive look to the buildings, with the lamellas inclined at different angles to allow for light and air to pass through.

Belvedere Palace, Vienna

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The Belvedere Palace in Vienna is an example of copper as used in Baroque architecture. Built in the early 1700s, the copper roof is still intact 300 years later and looks great today. Allegedly, the design was inspired by the shape of Ottoman army tents camped outside the city of Vienna.

Temppeliauko Church, Helsinki

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The Temppeliauko Church in Helsinki, Finland, is another stunning piece of modern architecture. Completed in 1969, this church was excavated out of solid granite bedrock, and features a large copper dome surrounded by 180 window panes that act as a skylight.

The church is known for its great acoustics, and has an organ with 3001 pipes! The copper adds to the rugged, cave-like interior, while its patina-covered exterior is visible on the top of the hill.

Jurassic Museum of Asturias, Spain

Located in Northern Spain on the Atlantic coast, the Jurassic Museum of Asturias is designed in the shape of a dinosaur’s footprint. The roof is made of a plywood frame covered with a copper plate to protect it from the marine air. Since the building was only opened in 2004, you can see that the roof is still primarily its original brownish copper color, and is slowly developing a green patina.

Minneapolis City Hall

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The Minneapolis City Hall was built between 1888 and 1909, and originally had a terra cotta roof. But when it started leaking, it was replaced with a copper roof instead. At the time it was installed, it was the largest and heaviest roof in the U.S., weighing over 180,000 pounds!

Fairmont Le Chateau Frontenac, Montreal

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The Chateau Frontenac is one of the most iconic buildings in Quebec, Canada. Because part of the roof was replaced in 2011-2012, it’s easy to see the difference between the original roof, which still has its green patina, and the renovated roof, which now has a shiny brown color.

Peckham Library, London

Finally, let’s take a look at the Peckham Library, a prize-winning building that opened in London in 2000. The exterior of the building is constructed with pre-patinated copper, and has a distinct bright green appearance, complemented with steel mesh and colored glass windows. Part of the building is elevated above the street to create a pedestrian area and reduce noise from street-level traffic.

(Video) Learn how to add patina to copper on Make It Artsy with Mary Hettmansperger (105-2)

Acquired vs. Applied Patinas

When designing with copper, it’s important to have a vision not just of how it will look today, but what it will look like in the future. Not all copper buildings will develop a patina at the same rate, and the ultimate appearance of the patina depends on the environment.

Buildings located in industrial environments will develop a copper sulfide patina due to acid rain, while buildings in rural areas will develop a basic copper carbonate patina. Copper in wet marine environments, such as the Jurassic Museum, can expect to develop a patina more quickly. Some exteriors are clad with copper alloys, rather than pure copy, which weather at a different rate.

If you don’t want to wait for an aquired patina to develop, you can create an applied patina using chemical processes. A simple vinegar and salt mixture can create an applied patina on a piece of copper jewelry or a decorative item. An instant patina isn’t suitable for use in architecture, but it might be long-lasting enough for an art project or an interior design feature.

Copper isn’t the only material to aquire a patina. Carbon steel woks, terra cotta pots, and wooden furniture items can all develop patinas, although they each have their own appearance. For example, Japanese knives are traditionally made using a process called nekonoshoben, which uses an acidic solution to produce a protective blueish patina on the carbon steel blade.

A metalworker can help you determine the best way to care for your copper patina to provide a consistent look or to help it age gracefully over time.

Types of Patina Available at CopperSmith

At CopperSmith, we do not boast about our excellent selection of beautiful patinas without good reason. We have a range of patina colors to choose from, so you should have no problem finding the right shade that matches your home décor. You do not have to wait years or decades to have the right shade of patina. We provide matured patinas that you can enjoy immediately.

Shades of patina available at CopperSmith include:

  • Natural Raw Copper [reddish pink]
  • Old Coin [reddish brown]
  • Antique [dull brown]
  • Dark Antique [dark brown]
  • Bronze [dark blue]

Not only do we understand the nuances of different shades of copper patina, but we also add an extra layer of beauty to copper furnishes that the patina itself cannot achieve: texture. The physical texture of the copper gives depth to, and brings the character out of, the patina.

Textures of copper patina available at CopperSmith include:

  • Smooth
  • Hood hammered
  • Beehive hammered
  • Light hammered
  • Hand hammered

The beauty of copper patina has yet another dimension of depth and elegance that is unique. Just as the hammered texture of copper changes how light reflects off its surface, three-dimensional carvings captivate the imagination by suggesting hidden stories behind each curve. Ornate carvings can imbue a copper item with a charming nature. Alternatively, they can add a dash of regal pride to an otherwise mundane household fixture.

Custom-designed carvings in CopperSmith products include:

  • Landscapes
  • Gardens
  • Royal emblems
  • Geometrical patterns
  • Birds
  • Fish
  • Bricks

Types of Copper Furnishing Available at CopperSmith

CopperSmith has copper furnishings for every room in the house: kitchens, bathrooms, dining rooms, bedrooms and even the garage. Browse our website to see all the different copper products that we offer.

Copper Range Hoods

Copper range hoods above the stove can easily become the centerpiece of the kitchen. Copper patina has a presence that will inevitably draw attention from all corners of the room. Decorate your range hood with straps and rivets that themselves can have textured patterns. Not only do range hoods serve the important safety function of removing fumes and particulate matter from the air, but they can also be a pleasure to the eyes.


Aside from the stove, the kitchen sink is a quintessential piece of furnishing in the kitchen. CopperSmith has apron sinks and barn sinks that display a face towards the kitchen that draws attention from across the room. Sinks are not just found in the kitchen but are also in the bathroom. Garages can have sinks next to the washer or for everyday use, so even that room can be enhanced by copper. Some people prefer to have copper sinks next to their outdoor grill or in their patio, making food preparation and clean up easier. Check this out if you're interested in learning about the different styles of kitchen sinks.


Copper bathtubs have a unique feel of luxury and character. Not only do they have elegant designs, but they are easy to clean, as well.


Copper tabletops are versatile pieces of furniture that can go into any room in the house, whether as a dining table, coffee table or nightstand.

Examples of other copper items at CopperSmith include:

(Video) Traditional Rainbow Patina on Bronze, Brass, Copper, and Steel

  • Light Fixtures
  • Mirrors
  • Knobs & Pulls
  • Towel Bars & Rings
  • Backsplash Murals
  • Tapestry Hangers
  • And more!

How to Create Your Desired Patina

Since we know the chemical reactions that cause the different shades of color in copper patina, there are ways that we can affect what color patina becomes and how fast patina forms. Creating artificial patina is a common activity among people who make copper jewelry and kitchenware. The following tips will teach you how to patina copper.

Making a consistent pattern of artificial patina on large furnishings such as bathtubs, tables and range hoods is more challenging than doing it on jewelry. For large objects, it is best to pick a piece of copper whose patina was industrially created by professionals.

For each of the following methods, the longer the copper is exposed to the homemade concoction of chemicals, the more intense the patina will become. You should be sure to test out the strength of your treatment on small objects such as coins and pennies before doing it on your prized copper possessions.

Keep notes about how much of each chemical was mixed, which will allow you to adjust the strength or effect of your home-made patination mixture for your desired effect. Test the method to see how fast the patina forms, so you know when to stop the incubation time.

Make sure you pay attention to safety procedures about handling any home cleaning agent. An adult should supervise children under 18. Household cleaning agents can cause irritation in the eyes, skin, nasal passage and lungs. They can also be dangerous if ingested.

Incubate with Hot Crushed Boiled Eggs

The hot boiled egg method is perfect for creating a brownish patina on copper. Eggs are hard boiled and then crushed to pieces in a re-sealable plastic bag or container while they are still hot. The copper is then placed into the bag and sealed for minutes to hours, depending on the desired shade of brown patina. The longer the incubation time, the darker the brown color. This method is ideal for small copper items, but large ones are difficult to manage through this technique.

Use Miracle-Gro

Miracle-Gro plant fertilizer is an excellent oxidizer of copper. For a blue patina, mix one part Miracle-Gro with three parts water for a solution that you can spray or wipe onto the copper. For a green patina, mix one part Miracle-Gro with three parts red wine vinegar. A patina will form within 30 minutes and become permanent within 24 hours.

Soaking in White Vinegar and Salt, Sawdust or Potato Chips

Soaking copper in white vinegar and salt will create a blue or green patina. Other ways of doing this are to bury the copper in sawdust or crushed potato chips soaked in white vinegar. The longer the copper is buried, the darker the patina becomes.

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Expose Copper to Saltwater and Ammonia Vapors

Spray the copper with a solution of salt water and then place the copper in a container that contains non-detergent ammonia. The copper should not be touching the ammonia liquid, but should be raised above it.

The sealed container will trap ammonia vapors that will then make contact with the copper. Be careful when handling ammonia: wear protective gloves, wear safety goggles and be near water in case you need to rinse ammonia off of yourself. Also, do not sniff ammonia and use ammonia outdoors or make sure the room is well-ventilated.

How to Naturally Influence the Color of Patina

There are ways to allow the patina to form naturally without applying chemicals to it. Exposing the copper to outdoor conditions will help patina to form. Outdoor conditions include fog, rain, snow, and heat. Leaving the windows open will change the temperature and moisture content of the room, so any copper objects in that room will also experience the changes.

You can purposely leave copper furnishings next to sources of heat and moisture, such as in the kitchen next to the stove or the back of the refrigerator. Leaving copper next to a window so that it receives lots of sunlight will expose the copper to natural heat.

Sealing the Patina to Keep Your Desired Color

The patina that forms from artificial methods can be easily brushed off, so it must be sealed to be kept permanent. Sealants can be wax, lacquer or a proprietary mixture of chemicals. Jewelry-making and craft stores carry multiple brands of sealants for protecting patina.

Since patina forms through chemical reactions between copper and molecules in the air, preventing the air from reaching the copper will stop any more patina from forming. Applying a sealant can also be a way to keep the patina that you like, preventing it from changing further.

Get Advice on Including Copper Furnishings to Your Home Décor

The experts at CopperSmith are waiting to provide expert advice on how to design the copper furnishings that are perfectly unique to your home and needs. We stand behind our money-back guarantee because we believe in delivering only the best service and products. We can send you samples of our copper patinas so that you can know the exact look and feel of our copper for yourself.

Our expert designers will walk you through the process and options, taking the guesswork out of the shopping and planning process. Our knowledge and experience make it easy for you to get the right furnishing that will have the right fit for every location and purpose.


Why wait any longer? Contact us, and we will put the shine in your day!


Is copper patina blue or green? ›

The green colour is simply the natural shade of the patina that forms over the copper surface; the patina protects the copper from deterioration and creates a light bluish-green facade which can be seen on many copper rooftops and copper structures.

Does patina change color? ›

Patina is a chemical process that happens naturally when metal is left to the elements. The metal oxidizes when exposed to air, much like an avocado (or any fresh surface for that matter) begins to turn brown after being cut. It is a chemical process. Patina is what makes an antique copper pot spot and richen in color.

What shade of color is patina? ›

Depending on what combination of these three is present, the color of the patina can vary from shades of green to shades of blue. Darker greens indicate an abundance of malachite and brochantite, while blues suggest that azurite is abundant.

What color is patina color? ›

This page shows RAL color 6000 called Patina green.
RAL 6000 Patina green.
Spanish:Verde patina
3 more rows

How do you make patina color? ›

Step 1: Add 4 Tablespoons of Joint Compound to your container, then Mix in 3 Tablespoons of fine sand. Step 2: Add 2 Tablespoons of Aleene's Tacky Glue. Mix thoroughly. Step 3: Add 1/2 Tablespoon – Light Green Craft Paint.

What is the fastest way to 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.

How long does it take for copper to turn green? ›

In coastal regions or heavy-industrial areas, the natural patina typically forms within five to seven years. In the country and rural areas, where the level of sulfur dioxide in the atmosphere is relatively low, the patina formation takes 10 to 14 years to attain a dominant stage.

What is the colour of old copper? ›

Ancient Copper is a dark, muted, apricot orange with a cinnamon undertone. It is a perfect paint color for a kitchen or dining room where warmth and gaiety are required. Pair it with green, yellow or blues.

What does old copper look like? ›

"Copper found at flea or vintage markets will most likely be well patinated." Copper corrodes in a very unique way. It does not rust. "Oxidation on real copper presents as a crusty growth of blues and greens set upon a powdery red coating on the surface of the copper."

Why does my copper look pink? ›

The process is called oxidization and happens because the copper combines with the oxygen in air and then gives up some of its' electrons. This can cause the color of the metal to change and can give rise to areas of darkening. Copper may turn a deeper orange, a pinkish shade or can even develop purple or blue streaks.

What does patina color mean? ›

ˈpa-tə- : a usually green film formed naturally on copper and bronze by long exposure or artificially (as by acids) and often valued aesthetically for its color. : a surface appearance of something grown beautiful especially with age or use.

Is patina just rust? ›

Patina is a naturally occurring process that iron goes through and shouldn't be confused with corrosive rust. Patina is actually good for iron as provides a protective layer. Cast iron/ductile iron will last many decades with little change if left unfinished.

Does patina look like rust? ›

The patina should not be confused with rust as the former protects the blade, while the latter causes corrosion and deterioration of material. Rust is a thicker layer of usually brown iron oxide with a reddish tinge formed by the reaction of iron and oxygen in the presence of water or air moisture.

Will baking soda darken copper? ›

This solution will turn your copper a darker brown, roughly the color of an American penny. Simply shake baking soda in a bottle of hot water one spoonful at a time, until additional baking soda does not dissolve. Spray the copper with the solution. Use a spray bottle to apply the patina onto the surface of the copper.

Can patina be brown? ›

Antiquing Patina creates an aged brown to black finish on bronze, brass, and copper. On iron, steel, aluminum, and zinc, it will produce a grey to black patina. It should not be used on stainless steel. Antiquing Patina does not need to be diluted, but may be thinned with distilled water for a lighter finish.

Is there a patina paint? ›

Patina Paint is infused with metal pieces and reacts when the Patina Spray is applied! Layers of Iron, Bronze and Copper Patina Paint can be layered to create an intriguing array of hues. To get a textured, eccentric look, be sure to dab on your Patina Paint and allow it to be a little messy!

Is there a patina spray paint? ›

Patina Stain Spray Cans are available in bronze, brass, copper, silver, hot rolled, rust, red, orange, yellow, verde (copper green), sky blue, blue, violet, white, black (gun bluing or PC9/PC-9), antique black (M24/M-24), brown for copper metal, and brown for all other surfaces. They are available as individual 12oz.

What makes copper turn blue or green? ›

The natural weathering of copper to the characteristic blue-green or gray-green patina is a direct consequence of the mild corrosive attack of airborne sulfur compounds. In the atmosphere, these compounds combine with water vapor to form dilute oxidizing acids which react with copper surfaces.

Can you turn copper back from green? ›

Acetone Solution

Another effective way to treat discoloration and remove oxidation is to rub the oxidation with a segment of light grit emery cloth, scrubbing until you can see the bright copper beneath. First, wet a rag with acetone and wipe down the corroded green area for this method.

What is blackened copper? ›

Definition of black copper

1 : melaconite. 2 : a product containing usually 70 to 99 percent of copper formed in smelting copper ores direct to metal without first forming matte or by remelting old or scrap copper and copper alloys.

How do you tan patina? ›

Exposure to the elements is the purest way for patina to thrive. Sunlight and heat will bring out our leather's golden tones. Rain and sea water will leave splash marks and natural oils from your hands will create darker patches to form.

How do you get dark brown patina on copper? ›

Mix darkening solution of 2 parts white vinegar, 0.50 part non-iodized salt, and 1.5 parts of clear, detergent-free ammonia. Spray on the area you want to patina and reapply every 1-2 hours until you get the color you want.

What does vinegar do to copper? ›

Acidic substances react with the surface of copper, causing it to tarnish and corrode almost instantly. This corrosion is highly soluble, leading to the presence of toxic copper salts in the food. This is why it is not recommended to use copper vessels for foods high in acidity, such as milk, wine, or vinegar.

Does water help oxidize copper? ›

Copper does not react with water, but it slowly reacts with atmospheric oxygen, forming a layer of brown-black copper oxide. In contrast to the oxidation of iron by wet air, this oxide layer stops further, bulk corrosion. A green layer of verdigris (copper carbonate) can often be seen on old copper constructions.

How long does it take raw copper to patina? ›

Copper goes green and turquoise after prolonged exposure to moisture. Without accelerating the process, it can actually take 20 years or more in dry climates for this patina to develop.

Will all copper turn green? ›

Over time copper will naturally change colors – transforming from a shiny brown color to darker browns, then blues and finally greens after a number of years. When exposed to the natural elements such as wind and rain, copper develops this “patina” which actually protects and preserves the metal underneath.

Does copper go green when wet? ›

Oxidation is common on copper when it is exposed to water and air over time. While this oxidized layer is not harmful, it does cause the copper to become corroded. This green colour is known as copper oxide and is basically a rusting of the metal.

How do you tell the difference between old copper and old brass? ›

If you hold a strong magnet to the metal in question and it responds, then you can rule out that it is copper. Check the metal item for an engraved letter “C” followed by three or five numbers. If you see an engraving like this, then you will know it is brass.

Is copper more orange or brown? ›

Since blue-green light is absorbed, its complementary color, red-orange, is reflected. Hence copper appears a red-orange color.

What does copper look like when it tarnishes? ›

Copper reacts slowly with the oxygen in the air—a process called oxidation. The process produces copper oxide, a brown or black compound, or tarnish. Eventually, other chemicals from the atmosphere like sulfur will turn the "tarnish" blue or green.

How can you tell pure copper? ›

All you have to do is clean your copper item with a mixture of table salt and vinegar and then observe the color change to find out if your object is made of copper. If the color that comes out after cleaning shinning reddish-brown, then it is indeed copper in a considerably pure form.

How do you remove pink from copper? ›

  1. Step 1: Make Paste. Mix 1/2 cup distilled white vinegar (or lemon juice, which is more acidic) with one tablespoon salt and enough flour to form a thin paste.
  2. Step 2: Scrub and Dry. Apply the paste to the copper surface and scrub away the tarnish with a cloth or scrubbing sponge.
29 Sept 2022

Does vinegar turn copper pink? ›

I have found that dumping old tarnished (brown) copper coins in vinegar (with a little added salt (NaCl)), results in the coins becoming pink and shiny within a few minutes.

Is patina blue? ›

You can recognize a patina by its characteristic colors: first you see golden yellow that changes to deep blue, which then transforms to purple and, in the end, to gray that darkens over time.

What color is copper tarnish? ›

Copper reacts slowly with the oxygen in the air—a process called oxidation. The process produces copper oxide, a brown or black compound, or tarnish. Eventually, other chemicals from the atmosphere like sulfur will turn the "tarnish" blue or green.

How long does it take copper to turn fully green? ›

In very dry conditions, copper can take up to 20 years to turn green! It also changes color in stages. At first, the copper will turn dull like a penny. Then brown, then darker brown, and finally it will start to turn green.

How long does it take copper to become green? ›

In coastal regions or heavy-industrial areas, the natural patina typically forms within five to seven years. In the country and rural areas, where the level of sulfur dioxide in the atmosphere is relatively low, the patina formation takes 10 to 14 years to attain a dominant stage.

Does pure copper turn green? ›

Copper has a beautiful reddish hue, but when exposed to the elements, the metal undergoes a series of chemical reactions that make it turn green. But why does this color transformation occur?

What is the blue on copper called? ›

The corrosive process produces an often beautiful effect

"Patina" is a term that refers to the blue-green layer of corrosion that develops on the surface of copper when it is exposed to sulfur and oxide compounds.

What does bronze patina look like? ›

Over time and when exposed to the elements, bronze undergoes a natural process called patination. Patina is a tarnish that forms on the surface of bronze through oxidation. It results in the distinct blue-green coating or some other shading you might see on old copper roofs and bronze statues.

What color is copper naturally? ›

Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air.


1. Heat Staining Copper Patina
2. Red And Green Patinas On Copper Jewelry
3. Rainbow Patina On Copper
(Sculpt Nouveau)
4. Patina Process: M38 Gel over Copper Sheet
(Sculpt Nouveau)
5. Deep brown and Darkening patina
(Sculpt Nouveau)
(WW Decorating)
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