Before you begin grinding and polishing concrete, it’s necessary to understand the make up and consistency of the substrate. Knowing the hardness of the slab will allow you to make smart decisions and effectively plan the project, including:

  • Whether you should use hard or soft bond tooling;
  • What grit to use to get the polish you want;
  • Whether you need to use a densifier and at what point to apply it;

One of the easiest and most effective ways to test the harness of the concrete is to use a Mohs hardness kit and measure the scratch patterns. Watch the video below to see exactly how we test concrete.

What Is the Mohs Hardness Scale?

Developed by Friedrich Mohs, a German minerologist, in 1812, the Mohs hardness scale compares the resistance of a mineral to abrasion, thus determining how hard it is, to one of ten reference minerals. This one to ten scale starts with talc, the softest mineral, as a 1 with a diamond as a 10. In addition to minerals, the hardness of industrial materials can also be checked, including concrete, flooring, and countertop materials.

Using a Concrete Scratch Test Kit

The test we use today to measure Mohs is a Mohs Hardness Test Kit with four double ended picks, and each pick has a tip that corresponds to a different level of hardness ranging from two to nine. This means that a nine pick will scratch anything with a hardness level of eight or below while a number two pick won’t scratch anything except incredibly soft materials, like talc.

To test your concrete, start with a number two pick and make a two-inch line coming toward you with firm, downward pressure. You want to try to leave a mark with the pick. If there’s no scratch line, move on to a number three, then a number four, and so forth, until a discernable scratch line is left behind. For example, if the number five pick doesn’t leave a scratch but the number six does, your concrete is a 5.5.

We recommend testing several areas where you’ll be grinding and polishing to ensure consistency. If you find your concrete is fairly soft, read our guide on how to polish soft concrete.

Contact Us for Concrete Polishing Equipment

The concrete hardness is just one factor at work at getting the results you want for your next project. No matter what kind of equipment you need, we carry the diamond tooling, chemicals, and heavy duty floor grinders you need to get the job done right. Reach out today to speak with a member of our sales team by calling   (815) 472-9744 or by filling out our contact form to get started!