What is 9H when talking about a Ceramic Coating?

Many Ceramic Coatings will have 9H or some even 10H in their names. But if not their names directly, almost all of them will have the same written into the description of the product.

What does it mean though?

If you go ahead and use google to get an answer you will most likely stumble upon the following:

"9H Ceramic Coatings get the 9H based on the Mohs scale."


Unfortunately, this is where most people would stop their investigation regarding the matter and would start having wild expectations from Ceramic Coatings and would, naturally, be outraged when they do not deliver.


What is the Mohs Scale?

Back in 1835, a german scientist, specializing in gemology and mineralogy, named Friedrich Mohs invented a method to determine the hardness of various minerals and a way to rank them. This method would be known as the Mohs Scale of Mineral Hardness. And that scale is what Friedrich Mohs would be known for the most throughout his career.

We use this scale even today and it is quite handy when it comes to Ceramic Coatings as well. Well any material really, but Ceramic Coatings is why we are here. Talc would be the softest material that Mohs used and he gave it a rating of 1, while a diamond was at that time the hardest known mineral and was given a rating of 10. Everything else we use he's put in between the two.

mohs hardness scale

Hmmm... So if we consider this scale when doing our assessment, that would mean that Ceramic Coatings would have a hardness level of about a Corundum or a Sapphire. Wow! That is amazing. That basically means that unless you are attacked by a diamond hailstorm you are unlikely to ever get a scratch on your car ever again.

While you're at it, you might give yourself a Ceramic Coating as well and become practically bulletproof. Brilliant!

If only... Obviously, that doesn't make much sense. Either Ceramic Coatings would be known by anyone worldwide or they would cost so much that only a handful of people on the planet would be able to afford them. Neither is true so let us dig deeper and do some more research.

Hardness is the resistance of a material to scratches while toughness is the object's resistance to chipping. When it comes to Ceramic Coatings we are interested in their hardness in most cases.

One thing in "9H" that definitely stands out when taking a closer look at the Mohs scale is the "H" part. There is no "H" on the scale, at all. The other thing to consider is that almost all Ceramic Coatings will have the word "Quartz" written somewhere on the product packaging. And quartz is 7, not 9.

So let us conclude what all this actually means!

Namely, the "H" stands for Hardness, and you might have seen 9H in school written on your pencil. This is where the "9H" comes from the so-called "Pencil Hardness Test".

The Pencil Hardness Test, also known as the Wolff-Wilborn test is a method of using graphite pencils to determine the hardness value of a surface, or more precisely, the coating.

The H in graphite pencils stands for Hardness, while the B stands for Blackness. The ones marked with B tend to be much softer thus leaving a darker line, while the ones marked with H would write a thinner, much lighter line due to their increased levels of hardness.

elcometer 501

The way we determine the hardness of a surface is by using a graphite pencil and pushing it along the surface under a specific angle using constant pressure. Since we know the hardness of the pencil used we can determine the hardness of the surface as well. After the test has been performed, if the surface remains undamaged then you would take the next pencil on the pencil hardness scale and redo the test until the surface gets scratched. At that point, the surface no longer can resist getting damaged and the tested surface receives a rating of the last pencil used that did no damage.

For example, you could start from an H pencil and go up in hardness all the way up to 9H. If the surface that is being tested resists all pencils until it gets damaged by a 7H pen, it would get a 6H rating.

A handy tool that can be used to perform the Wolff-Wilborn test is called an Elcometer 501. Using such a tool is extremely handy because it will keep the pencil at a fixed 45-degree angle, and it will provide a constant amount of force, thus providing repeatable results that are reliable.

Ceramic Coatings get their 9H hardness rating using the method described above. If you wanted to refer to the Moh scale a Ceramic Coating would receive a 6 to 6.5 rating just below quartz, depending on the quality of the Ceramic Coating used.


Do all Ceramic Coatings have a hardness rating of 9H?

No. Some quality products do, but unfortunately, some are very liberal and vague when it comes to their product descriptions, while others are straight-up lies. And as a newcomer to the world of paint protection and Ceramic Coatings, it is hard to know which is which.

That is why we like to test products using the same method before making any judgment on our part. We do real-world testing and strive for situations that most people would have in their day-to-day life.

If you would like to know more about the testings we do to rate the Ceramic Coatings we use or have used at some point, please check out our Reviews part of our blog.

water beads on ceramic coated surface

So can Ceramic Coatings have a hardness of 10H?

Well, the conventional pencils range from 9B, the softest, all the way to 9H which is the hardest pencil. Some manufacturers claim they produced pencils that have a 10H hardness.

And technically if you wanted, you could use that pencil in the Wolff-Wilborn test.

Do such Ceramic Coatings actually exist or are they just marketing ploys to reach more customers? Well, if you ask us, we believe that only some high-quality industrial-grade products that are thick enough and slippery enough when cured would have such a high hardness rating. So for the average consumer, 10H Ceramic Coatings are more of a unicorn than reality.


If I coat the car with multiple layers of Ceramic Coating, will it have a higher hardness rating?

This one is a no. Installing multiple layers of Ceramic Coating on a car will only increase the thickness of the coat. Its rating will not be affected.

For example, you can stack two wooden planks on top of each other and while they will be harder to pierce through than just one plank, they will still be as easily scratched.

It might take more scratching to go through the coating, but it will not be more resistant to scratches. If you would like to learn more about multiple layers of Ceramic Coating on a car read this article here.