After cleaning, the grain of the concrete must be exposed to ensure maximum adhesion of the coating to the concrete. There are a primary types of surface preparation for a concrete floor: acid-etching and surface abrasion.

Acid-etching is the process of using an acid, usually muriatic acid, to dissolve the concrete dust that is always present on unprepared concrete. Since concrete dust is alkali, the acid does a good job of reacting to and dissolving the dust and then it can be removed with a simple wash-down. To accomplish acid-etching, simply take muriatic acid, available at any pool supply store, and dilute it with water at a ratio of 1 part acid to 3 parts water. This can be applied to the concrete using a watering can. When you can just start to see the grain of the concrete coming through, neutralize the acid solution with clear ammonia. The resulting solution is nonhazardous and can be washed down with water.

Surface abrasion is ideal for situations where it would be difficult to contain the large amount of water used in acid-etching

 There are multiple methods for surface abrasion including sandblasting, shot-blasting, and grinding. Each of these methods provides a good solid grain in the concrete for the coating to adhere to. The primary disadvantage of surface abrasion vs acid-etching is the large amount of concrete dust that is generated. However, surface abrasion is ideal for situations where it would be difficult to contain the large amount of water used in acid-etching.
All of these procedures may seem like a lot of extra work, but ultimately a good surface preparation will ensure that your floor coating will withstand the test of time. When it’s time to recoat, a basic cleaning and a quick sanding with a sanding disk will be all that’s required to prepare the epoxy surface for a new coating.