Pre-cleaning is not necessary; however, as with any disinfecting product, gross soil must be removed prior to use. These are the specific directions for use:
To use as a disinfectant: Remove gross filth or heavy soil with normal manual cleaning procedures. Spray area until it is covered with the product. Allow surface to remain visibly wet for 2 minutes. No scrubbing necessary. Allow treated surfaces to air dry or wipe off with a clean cloth.
To use as a cleaner: spray soiled area and then wipe the area with a dry paper towel or lint-free cloth.