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The Difference and Full Comparison of Patina vs Rust

Last Updated: June 21st, 2022

Fixing the furniture around your house can be a hassle. However, if you can identify the problems associated with each piece, your work will be much easier. 

So, can you locate the issues between patina vs rust? In a nutshell, rust refers to the browning and erosion of metal like corten steel and cast iron that can’t be avoided. Patina refers to the tarnish or bronze glow in metals that appear on the metal surface of copper and copper alloy.

Both might be a problem requiring extraordinary administrations to an inexperienced person. However, Patina isn’t entirely a bad issue. So, are you interested yet? Well, scroll down and keep reading patiently.

Patina vs Rust- Comparison Table

Patina Rust
It forms due to exposure in an oxidized area or when the object comes in contact with an oxidizing agent.  Rust is caused due to extended exposure in the air that has high humidity or moisture levels.
It has a chemical composition of Ammonium sulfide Liver or Sulfur Cupric nitrate Ferric nitrate It has a chemical composition of Hydrated iron (III) Oxide Hydroxide. 
It can be good for the furniture or accessory since the oxidizing causes a bronze to appear that will protect the item in the long run. It is bad for the accessory or furniture since it causes the metal particles to break down and erode.
It has a bronze tone with a matte sandstone yellow color. It can also be gray or black in color. It is red-brown or orange-brown in color.
Patina doesn’t cause any bodily harm unless you are going to use it in its raw chemical state. If the rust particles enter your bloodstream by mistake, this could result in disastrous effects.

Patina And Rust – Key Differences

There are plenty of differences in the competition between Patina vs rust. We have already given you a short overview of the differences between the two. Well, it is time that we delved deeper into the key differences. 

We have compiled a list of the critical differences and a brief outlook on the issues. These differences are as follows:

Formation

When it comes to the formation or origin of rust and Patina, they each have their own sources that differ entirely from each other. 

When we talk about Patina, it is actually formed when the metal, usually copper or its alloy, comes in contact with an oxidizing agent. It can also be formed due to long-term exposure to an oxidizing environment. 

On the other hand, Rust forms when a metal comes in contact with water molecules, whether from a large water body or humidity in the air. While we are saying metal, steel and iron are the most sustainable to rusting because of their chemical characteristics. 

Chemical Composition

The chemical composition of Patina isn’t fixed. It depends on what base chemical has caused the metal or metallic substance to show patina growth. It is a fact that different chemical components can cause different types of patina chemical composition. 

These chemicals include different oxides, sulfides, carbonates, and sulfates. While not as essential, other elements like carbon dioxide or sulfur-bearing compounds could also be associated with storing oxidizing agents.

Rust isn’t fixed to one single component either. It is a broad term used to represent a series of oxides. While these oxides are red under typical conditions, green oxides can also form rust, given the ideal environment. 

Color On Metal

Patina usually comes in a gray-black color with a bronze tone. The most popular colors in Patina are green and blue. However, these aren’t the only colors that Patina can form. 

Depending on the surface of the formation, the color achieved by the Patina includes Matte sandstone yellow, white red, black, deep blue, and green. 

On the other hand, rust can achieve a single color only. This color is orange-red or brown-red, depending on your perception. It usually resembles raw iron oxide ores. Suppose you notice this color in your metal accessory instead of any other colored layerings, like reen. Take proper measures to prevent further rusting. 

Good Or Bad

If we consider Patina over a metallic surface, it is suitable for the accessory in the long run. Though patina forms from corrosion of the surface, it protects the surface from further corrosion or dust. 

Even a thin layer of Patina can help cutleries withstand rust from an environment with incredibly high moisture. That’s why antique collectors will often layer their artifacts with Patina.

On the other hand, Rust isn’t what we will be able to call helpful under any circumstances at all. Not only is it aesthetically degrading if it can get into your bloodstream, but rust can also prove to be highly toxic. 

How Is Rust different from Patina?

Rust patina are similar in the way that both of them have the same sources of corrosion. However, even then, there are several reasons that contribute to making these two chemical phenomena different. Below we have listed out several of these reasons as follows:

  • Rust is caused by the deterioration of metal particles whereas Patina is a form of tarnish that is formed by oxidation. 
  • Patina is merely the discoloration of the metallic surface whereas rust is the erosion or degeneration of the metal ions. 
  • Rust is formed by contact with both moisture and oxygen. On the other hand, the Patina is formed with exposure to oxygen alone.
  • Patina is usually gray-black or bronze in color. Rust, on the other hand, can be reddish-brown or orange-brown depending on how you perceive it.
  • Patina can be visually appealing to most people due to its vintage or retro look. Rust isn’t visually attractive at all. In fact, it gives people a sense of dread.
  • Patina doesn’t happen in most metals other than copper and metallic alloys. Red rust can occur in any metal, especially in steel and iron.

What Is Patina?

Patina refers to a type of tarnish that can occur in many forms of metal that contain copper or copper alloys. The formation of Patina is contributed by various compounds like oxides, carbonates, sulfates, etc. Most surfaces that can form Patina include

  • Anything, like furniture, wind still, chimes, etc, outside your house that is exposed to the air.
  • Old metallic substances like ancient bronzes and copper knife accessories have not been painted or fused with sacrificial metals.
  • Metals like copper and metallic alloys are made from most metallic compounds, including zinc, iron, brass, etc. 
  • Acid rain and hydrogen peroxide falling on any metal surfaces can form a protective layer of the oxide layer that is the patina. A region of a thunderstorm can also cause Patina. 

What Is the Usage Of Patina?

Patina is mainly used to reinforce old buildings to preserve their natural state for generations. An example would be the admiralty statue of Joseph I in Portugal.

This status is hundreds of years old. However, since it was preserved with a natural case of patina formation, it has survived through years of weathering. That’s why you will often find black-colored carbon knives in the market.

  • Many people often mistake Patina as a form of rust when it protects the item from further rusting. 
  • It can also refer to accumulated changes in surface texture and color that result from the regular use of an object such as a coin or a piece of furniture over time.
  • Patina can also be artificially applied to an accessory. Many artists and metalworkers often deliberately add patinas as a part of the original design and decoration of art and furniture
  • The basic palette for patinas on copper alloys includes chemicals like ammonium sulfide (blue-black), liver of sulfur (brown-black), cupric nitrate (blue-green), and ferric nitrate (yellow-brown). 
  • Artists often accelerate the patination process by applying heat to the chemical substance needed for the shielding.

What Is Rust?

Rust is merely an iron oxide formed from iron’s reaction with oxygen and water. Here oxygen is the reagent while water acts as the catalyst in the process. Rust is typically associated with the corrosion of refined iron.

Rust can be generally termed oxidation. However, it is far more than that. It describes a chain of processes that causes a metallic substance to lose its electron or gain oxidation as a by-product. While rust can occur in most metallic compounds, it is more common in iron and iron alloys. 

The primary catalyst for the process is water. The water molecules are used to enter the microscopic cracks in the metal compounds and cause them to crack. This increases the rate of erosion as compared to rusting without any catalyst.

How To Prevent Rust From Forming?    

Unlike Patina, rust isn’t good for metallic structures. While all metals are susceptible to rusting, there are specific ways to prevent it. These methods are as follows:

Rust-resistant Alloys

While most iron alloys aren’t resistant to rust, steel can be made with special infusions that can be used to make the steel component free from any rust formations. These types of alloys are called stainless steel or high carbon steel. 

Using stainless steel alloys is one of the most common ways of preventing an accessory from rusting. The weakness of stainless steel is that it is not as malleable as iron. As a result, stainless steel isn’t fit for industrial usage. Carbon steel knives are also quite popular.

Applying Oil 

A coating of special oil on top of your metal can also cause the formation of rust to become dormant. Do note that this isn’t prevention. The oil only stops the rust from spreading any further. 

The oil inhibits the moisture and prevents the water from seeping in. Besides, if you’re going to apply oil to machinery, it can also act as a lubricant. That is why most gun owners prefer to use oil to prevent rust formation. 

Painting 

Painting is also one of the most popular rust-forming precautions. If you have a heavy metallic body but can’t afford most prevention techniques, painting that body can be a good call. 

Car manufacturers paint their cars for this reason. Do note that not all paint coats can prevent rust. It is essential to do your research well and find out the right coat to paint to prevent the formation of rust.  

Galvanization

is also called the sacrificial method because we are using another, more accessible rust metal to prevent the main metal body from rusting. Giant freight ships were made from metal using this method of metal coatings to keep their ships from rust. 

Zinc is traditionally used because it is cheap, adheres well to steel, and provides cathodic protection to the steel surface in case of damage to the zinc layer. Cadmium plating is commonly preferred in more corrosive environments (such as saltwater).

FAQs On Patina vs Rust

How Can I Patina Metals Quickly?

If you want to form a bronze patina on a metal part artificially, you will need ammonia, salt, and paper towels for the purpose. 

Spraying ammonia and salt on top of the metal will oxidize and promote the formation of the patina. The towels serve the purpose of drying the metal to remove excess alkalinity. 

Is Patina toxic?

No, Patina isn’t toxic. Most people might think that since rust is toxic, Patina is toxic. However, they are wrong. Patina is merely the discoloration of a metal object. It doesn’t cause anything that would exceed this. 

Can Silver Rust In Water?

Yes, silver can rust in water. This is because moisture causes silver to oxidize, darkening its surface during the rust chemical process. 

However, do note that the silver will not be damaged physically, unlike most rusting. It will only lose its outward appearance. Carbon steel knife is the only exception to rusting.

How To Remove Rust From Metal?

Scrapping is a decent way of removing the rust spots from the metal. You can use a scraper, steel wool, or sander to scrape off the rust areas on the accessory. 

You can also choose to soak the metal in white vinegar, mustard, baking soda, or lemon juice. This will slow down and possibly remove the rust. 

What Are Tarnish?

Tarnish refers to the discoloration of metal surfaces caused by various reasons. All tarnishes are formed due to oxidation on the metal compound. Therefore, Patina is a type of tarnish.

Conclusion

Rust and Patina do have some similar properties. This is particularly true since oxidation is responsible for the formation of both these phenomena.

However, in between Patina vs rust, Patina is more beneficial. Patina can protect the surface of the metal, whereas rust will deteriorate the metal structure.

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