Accumulation of dirt, dust particles, and/or other debris on the paint film.
Exterior: soil splashing onto siding, air pollution, and car exhaust.
Interior: air-borne dust and household dirt.
Wash the surface; if it comes clean, painting may not be necessary.
Interior - Remove stains, dirt and marks, use a soft cloth or sponge with water or a general-purpose household cleaner. Penetrating stains and marks may be removed either by carefully using an abrasive cleaner and water or by applying a solution of household bleach diluted with water and then rinsing with clean water.
Exterior - Remove dirt with a scrub brush and detergent solution or pressure washing, followed by a thorough rinsing. While dirt accumulation cannot be eliminated entirely, satin, gloss, and high-gloss paints are more resistant to picking up dirt than flat paints due to their smoother finish.