It is a great temptation to start painting without spending time to properly prepare the surface, but this can be a big mistake. Shortcuts on surface preparation can cause even the highest quality paints to fail prematurely. In fact, experts maintain that inadequate surface preparation is the single greatest cause of paint failures.
Whether you are doing interior or exterior painting, good surface preparation requires that the surface be as clean as possible and in good repair. Paint performance depends on good paint adhesion, and paint adheres best to surfaces that are clean and sound.