The tack cloth’s purpose is to remove any dust or dirt that may have settled on the surface you are painting. It will help ensure a better final finish.
Use the tack cloth just before each step of painting, including primer, color, and clearcoat. To use the tack cloth, remove it from the wrapper, bunch it up like crumpled paper, and lightly wipe the surface to be painted. Do not press hard, and there is no need to wipe multiple times. Simply wipe the surface lightly with the tack cloth and proceed with your next coat of paint.