Cobalt vs Black oxide: Which, when & why? Answered!

Two commonly used options for protective coatings for metals are cobalt and black oxide. Both coatings offer unique properties and benefits, making them suitable for various applications. This article will delve into the characteristics, applications, and advantages of cobalt vs black oxide coatings. By understanding their key differences, you can decide which coating is best suited for your specific needs.

Cobalt Vs Black Oxide

1. What is Cobalt?

Cobalt is a hard, lustrous, and silvery-gray metal that belongs to the transition metal group. It is known for its high strength, excellent magnetic properties, and resistance to corrosion. Cobalt finds applications in various industries, including aerospace, automotive, and electronics. The metal is often used in the form of alloys, such as cobalt-chromium and cobalt-nickel, due to its desirable properties.

Cobalt offers several advantages as a coating material. It provides exceptional wear resistance, making it suitable for high-wear applications. Cobalt coatings also exhibit good thermal stability, ensuring their durability under extreme temperature conditions. Moreover, cobalt coatings can enhance the aesthetics of the underlying material, providing a smooth and polished appearance.

However, cobalt coatings can be expensive compared to other coating options, and the application process may require specialized equipment and expertise. Additionally, cobalt coatings may not be suitable for certain applications where their properties are not required or cost considerations outweigh their benefits.

2. What is Black Oxide?

Black oxide is a conversion coating applied to ferrous metals to provide corrosion resistance and improve aesthetics. The black oxide process involves a chemical reaction that converts the surface of the metal into a layer of black iron oxide. This layer acts as a protective barrier against rust and corrosion, prolonging the lifespan of the coated metal.

Black oxide coatings find extensive use in various industries, including firearms, automotive, and tool manufacturing. The coating not only provides corrosion resistance but also imparts a visually appealing black finish to the metal. This makes black oxide coatings highly desirable for decorative and aesthetic purposes.

One of the major advantages of black oxide coatings is their cost-effectiveness. The process is relatively simple and can be applied to a wide range of metal parts. Black oxide coatings also offer good lubricity, reducing friction and wear. However, it is important to note that black oxide coatings may not provide the same level of durability and wear resistance as other coating options like cobalt.

3. Cobalt vs Black oxide: Differences

I. Specialty

Just because cobalt drill bits offer the best performance and black oxide drill bits are the cheapest doesn’t mean these are the only options.

It is possible to make a case for a third option, a combination of both! For a small, one-time job, black oxide drill bits are probably the best option. 

But for a larger, long-term project, you may want to opt for cobalt drill bits. Consider your situation and the material you want to drill.

What do you need your drill for? Suppose you’re just drilling into softer materials like wood. In that case, you’ll most likely be okay with getting a set of quality black oxide (or even simple HSS) drill bits.

II. Hardness

Despite what you may have heard, black oxide drill bits are not the same as HSS bits. These drill bits are made of regular HSS bits heated to 950 Fahrenheit to achieve a black oxide finish. 

This heat softens the HSS bits, which means they are not as hard as cobalt. If you need drill bits for metal, titanium, or cobalt are great options.

Cobalt drill bits are the hardest, but they also have a uniform cobalt concentration throughout, making them harder.

III. Material

All materials are worth drilling through with Black Oxide drill bits, but they work best with wood, metal, and plastic. 

Cobalt drill bits are perfect for drilling hard materials like cast iron, stainless steel, and titanium. Some people prefer cheaper bits for drilling through the soft material. 

Still, many people find that this leads to incomplete drilling, which leads to the need for more work later on.

IV. Purpose

Some experts will disagree, but experts agree that black oxide bits are the best general-purpose drill bits. You can use these drill bits for metal as well.

One of the main reasons it’s the right choice for many different jobs is because they are affordable and pocket-friendly. 

Their affordability and pocket-friendliness make them the right choice for handy amateur persons, DIYers, or hobbyists. 

Cobalt drill bits are used to drill through hard metal and are used for industrial & professional purposes.

V. Durability

Cobalt drill bits have higher durability than steel drill bits because of their superior hardness and strength.

Why use an oxide bit when you can use a cobalt bit? Black oxide drill bits tend to lose their edge when used constantly on challenging material. 

It is known that black oxide drill bits can also be re-sharpened, but that of cobalt bits overshadows their durability due to their hardness.

In contrast, cobalt bits are custom-made for drilling on materials like cast iron, stainless steel, and one of the most demanding metals.

The uniform concentration of cobalt in the drill bit can be sharpened if it loses its edge or gets worn at the head. Hence, cobalt bits are more durable.

VI. Cost

Black oxide drill bits, with their affordability, 50% more durability, and all-purpose uses, are this debate’s clear winner.

While cobalt drill bits are the most expensive, they are also the most durable and the most resistant to corrosion. They also boast an improved resistance to heat and can be used in high-speed drills.

4. Black Oxide Vs Cobalt: Features and Specifications

I. Non-corrosive

To create a rust-resistant material, HSS drill bits are heated to 950 Fahrenheit. Because of this process, the drill bits’ performances and life span are enhanced. Rust is not a problem with cobalt drill bits.

That’s because they are made from 5 to 8% cobalt alloy, with high-speed steel. The increased resistance from rust makes them popular among builders and other people who work with metal.

II. Speed

There is less friction caused by the black oxide coating, which lends regular high-speed steel with more incredible speed.

A cobalt drill bit is a type of drill bit that is designed to drill quickly due to its ability to drill quickly, among other things.

III. Durability

Black oxide drill bits have a hard exterior 2x more durable than a regular drill bit, so they last 50% longer.

Few things are as durable as cobalt drill bits, which are known for their exceptional toughness. The material they are made of is far more robust than black oxide or titanium, making them well-known among handymen.

IV. Versatility

A black oxide drill bit can swiftly drill through different types of wood, including oak, maple, and pine. These drill bits can be invested in Woodworking to create a precision hole.

Cobalt bits are known for their extreme heat resistance, which, when combined with their sturdy shell, can drill through hard metal, such as cast iron, titanium, etc.

V. Re-sharpening

In the case of a dulled head, a black oxide drill bit can be quickly sharpened with a drill bit sharpener, and it will be as good as new.

Re-sharpening cobalt drill bits are more manageable than re-coating titanium bits. Unlike titanium bits, cobalt bits do not have to be re-coated with oxide.

A uniform concentration of cobalt makes them more durable than titanium bits.

VI. Affordability

What better way to get the job done than to use the most economical drill bits? Black oxide drill bits will be sure to save you the headache of spending your money on expensive drill bits.

I found cobalt drill bits are the costliest ones because they are made with challenging material. But experts will tell you that Cobalt drill bits are worth the cost because they drill more efficiently and they will last a long time.

VII. User

Many times drill bits are used as the best general-purpose bits. Black oxide bits are not different; they are ideal for novices, amateurs, and hobby drive handy persons.

Newbies with a Cobalt drill bit at home are sure to have a short lifespan. They are only meant for heavy-duty jobs in an industrial or professional setting, so you should put your money to better use.


I. What are black oxide drill bits used for?

In any activity, a black oxide drill bit is a perfect choice. Some that can be used in most activities are wood, soft metals, and plastics.

II. Is cobalt harder than black oxide?

Correct! Cobalt drill bits are harder than black oxide drill bits.

III. Can you drill stainless steel with black oxide?

Black oxide is suitable for work on steel, copper, aluminum, brass, oak, maple, etc.

IV. What are HSS drill bits used for?

HSS has a vast selection of functions, which can use in most activities. Suitable ones are wood, soft metals, and plastics.

6. Conclusion

Understanding the differences between Cobalt vs Black oxide has never been more accessible, as our comparison above has highlighted. With a more durable coating and will not show scratches as quickly.

Cobalt is the more cost-effective option for those who need a coating that will withstand a long time of use. But those on a budget may find the cheaper Black oxide coating to be a better option. In conclusion, it all depends on your needs.

7. You May Also Like!

Hello. You've come to the right place if you want to learn more about power drills and how to make your home improvement projects go quicker and easier. I'm Jacob P., the founder and content writer of Anyone who needs assistance with a project or has a query about how something works (or doesn't) can count on me to share my expertise.

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