Etching is a crucial step that must be done to prepare concrete for painting. When you are applying a coating of any kind to concrete, the coating must be able to adhere to the surface. Etching is a deep cleaning process that maximizes the bond between paint or protective sealants and the surface of the concrete. Concrete etching is the process of applying an acid and water solution to a concrete floor in order to roughen the surface of the concrete. The acid wash opens pores in the concrete, which ensures strong adhesion of the new coating to its surface.
Along with creating a rougher texture for the coating to bite onto, it also neutralizes the alkalinity of the concrete, which further increases the bond of the coating to the concrete. Neglecting to prepare the concrete by using acid or mechanical means before coating it can lead to a poor paint bond that will not last.