Concrete Preparation: Grinding

A concrete floor undergoing the grinding process

The single most important step in the epoxy floor coating process is the concrete preparation. Even if you use the best materials in the world, without proper concrete preparation your coating system is doomed to fail. There are various methods of concrete preparation; some are sufficient, and others simply are not. In this blog we will briefly explain the different methods of concrete preparation, most importantly, grinding.

Before we get into the different methods of concrete preparation, you have to understand why concrete preparation is so important. Epoxies require a rough texture profile in order to properly bond to the surface. Much like spray paint, if you try applying a coating to a smooth or ill prepared surface, it will peel in no time at all. This texture is known as the Concrete surface profile (CSP). The CSP is ranked on a scale of 1 to 10, 1 being a completely smooth surface, and 10 being a very rough surface. The ideal range for an epoxy floor coating is between 3 and 4. In this blog we will discuss the different methods of concrete preparation, and whether it will produce a sufficient CSP or not.

For more information about CSP’s:

Acid Etching and Water Jetting

Acid etching and water jetting are 2 of the most popular methods of concrete preparation for DIY epoxy kits.  While this is better than doing nothing, it still will not create enough of a CSP for a coating to properly adhere to. These methods produce a CSP of 2 or less, which is well beneath what is required. Acid etching and water jetting are more of a way to clean concrete rather than introducing a texture profile. If you use these methods you will find your coating will peel away, as it never was properly adhered to begin with.

Rotomilling and Sandblasting

Rotomilling and Sandblasting produce a CSP of over 4, which is simply overkill for epoxy floor coatings. It creates a texture that is too rough and can potentially be visible through the coating without proper millage (thickness). Try to avoid contractors that use these aggressive methods of concrete preparation; they are simply unnecessary.

Concrete Preparation: Grinding

Grinding is the ideal method of concrete preparation for epoxy floor coatings. It creates a CSP of 3-4, which is perfect for epoxy floor coatings. There are 2 main varieties of grinders: electric and propane. Both do a far better job than the previous methods explained, however they have specific strengths and weaknesses. 

Electric grinders are good for smaller spaces that can be hard to access with larger equipment. However, the tradeoff with electric grinders is that they are less powerful than their propane counterparts, but are definitely sufficient for all jobs. Additionally, electric grinders comparatively take longer to grind a space than propane grinders. 

Propane grinders are more effective than electric grinders, given they are larger and more powerful. Additionally, they are safer in commercial environments, or any larger space. This is because of the absence of extension cords, reducing trip hazards and electrical hazards. Propane grinders produce virtually no exhaust emissions, allowing them to be used even in indoor spaces. There is essentially zero risk of propane combustion given the specifically high temperature that it ignites at. Unlike gasoline which ignites much easier, there are no worries about the flammability of the propane. 

Always ensure your contractor uses proper concrete preparation methods. If they do not use grinders, find another contractor that does. Any other method will either be insufficient or overkill. The importance of concrete preparation cannot be overstated. Be sure to ask your contractor to walk you through the process they use to prepare concrete.

See our next blog for the advantages of hydro-epoxy, a moisture mitigating epoxy that is a must for damp environments: