We are ultimately in the business of coating concrete. Before we coat the concrete we have to grind the surface of it down to expose the inner sponge like structure so that our products can penetrate it and hold on tightly for a bond that will never let up. It seems weird to people who don’t work with concrete for a living that different concretes differ in their hardness. But we are concrete nerds and this excites us.
Concrete hardness differs because of many factors. The heat and humidity when the slab is curing. The different materials and chemicals that are mixed into it at the plant. The amount of time the mix is in the truck before it is poured, etc., etc., etc. We can more or less tell the hardness of concrete by the location in country. The map below gives us a rough idea of what concrete hardness looks like.
Friedrich Mohs was a German geologist. In 1812 he invented a test to tell the hardness of minerals. It is called the “Mohs scale of mineral hardness”. It is a scale of 1-10 in which 10 is the hardest and represents the hardness of a diamond. It works down from there to 1 which is the softest and represents the hardness of talc a soft chalk like mineral. Today we use test kits that tell us what the Mohs scale of mineral hardness is on the concrete we work on.
Why does this matter to me? When someone comes to work on your garage floor they need to be professionals. If they grind the concrete as if it is hard and it is soft they will take too much off the surface and leave scars in your floor. If they grind it as if it is soft and it is hard they won’t expose enough of the inner structure for the liquid state products to penetrate. Which means your garage floor will peel up where the tires first hit it. Just like a DIY job.
In the end you need someone who understands and gets excited about such boring and mundane things as concrete hardness. We are concrete nerds and we are, and will always be excited to put a professional coat on your garage floor.