Myth of the Coating Hardness

Myth of the Hardest Coating 12H ?!

There are a lot of rumor has it when you come across with car detailing service, when promoter offering you the package of the car coating. No matter it is Titanium Coat, Ultimate Coat or Superman Coat, you will always been educated with Hardness Level of the solutions they use. So, how to justify the hardness? most of them claim they are 9H, some of them even claim they are 12H ?! is that the higher the better?

First, we need to know what is this H mean, this is a measurement unit for the lab (commonly reference to ISO 15184:2012) to use as the Pencil Hardness Test on the subject. and below is a report from SGS (world's leading inspection, verification, testing and certification company) :

As you can see from the report, the test result is written:

No marking with 9H pencil (Tested subject coated with Tevo BodyGard)

Why the result is not straight forward as 9H ? and it no mark even on 9H, is that mean the hardness is actually beyond 9H ? Base on the SGS expertise explanations, the test is only able to carry out only maximum 9H pencil test, and anything beyond that is out of measurable range. Now here the questions....

Where did the 12H come from ?????? 

Lets go on with the deeper discussion:

 

The picture beside is the material hardness chart widely used as the comparison between coating. Most of them claim they are 9H which is almost at the par of diamond hardness. Public using this cart for public understanding about hardness easily and can be visualize.

If you want to study more on Hardness, there is more you need to know other than just surface hardness, because there is some hardness also refer to material hardness, which measurable by using:

Vicker Hardness Test [HV] - Pyramidal diamond indenter

Rockwell Scale [HR] - Depth penetration indenter

HV measurement is the most common and widely used to measure material hardness, not just surface hardness. And for your information, diamond consider 10000 HV and carbon steel is 120 HV. These are the real and practical hardness measurement unit which can be and widely use in physics calculations method.

In the nutshell, Mohs Hardness Scale is only for market evaluations reference, do not mean that 9H surface coating is as hard as corundum or diamond.

*Recall: even Mohs do not have scale for hardness above 10H

So, is that greater the hardness is better ? 

The answer is Yes, but no.

Yes, is mean with higher hardness, higher the scratch resistant, and it also somehow prolong the durability of your coating performance. higher sustainability on abrasion and the weathering issue.

Since there is so much benefit, than why no?

No, there is only one single cause, the coating base is not strong enough to support the hardness of the coating. It can be stimulate with your imagination with 2 scenario:

1. a super hard & thin layer of glass on a soft sponge, 

and compare to

2. a super hard & thin layer of glass on a metal plate,  

when both glass contact with impact , BOOM ! you can easily guess the first glass will be crack and turn into piece, and the second glass maybe still in one piece. This theory is totally same goes to car coating. Is your car lacquer is strong enough to be the base?

As you can study through Tevo or any other branded solutions provider, they are always differentiate the solutions for difference hardness/type of surface. Usually plastic as the softer flexible coating, and the metal/rim can be coat with the highest hardness coating. Last but no less, the car body coat, the expert will use only the coating hardness between 6-9H, which higher than car lacquer layer is good enough.

  

Erm, is that 9H consider scratch proof ? 

There is NO such thing as scratch proof, at least not by a single layer of thin glass coating.

Honest detailer only claim the coating can improve the scratch resistant level, even bulletproof layer can be scratch. There is a lot of marketing gimmick hitting the coated surface with "something" which is not very sharp or hard, and this actually can be done even without coat, as long as the impact is no go over deep on the surface, any mark from the impact can be easily wipe off with cloth.

Ok, do hardness really matter ? 

This is really a sensitive questions, for man, the priority is still the appearance, right? LOL
In the real case, car is mean to daily drive usage, with certain hardness is good for some damage prevention as you can see from the picture above. But how you justify the hardness is there?

The hardness is really hard to justify between each brand, as long as they do have certifications, i think that is all you can assure. Scratch warren-tee is a bonus add on for the package selections.

Last but no least,

The thickness is another contrast when comparing about hardness:

The thicker the coat, the higher the resistant can be provide, this is a basic knowledge of the physic, if you hardness is only minor difference between each one. So why don't we take a look at the other angle, thicker is for sure giving the better protection when come across with the physical damage/scratch.

And from the picture, which retrieve from a japanese expert detailer 東京都板橋区のCAR POLISH AUTHORITY (カーポリッシュ オーソリティ) tested with Tevo BodyGard S36 & S60, found the solid contain is actually higher than Brand A & B which is from some well known branded products. From the test result we found that the solid contain is up to 4 times more! which mean when it is coated and let dry/cure on the surface, it will be 4 times thicker than other brand too!

So, you know what you should choose now?