What is Mottling? Mottling is the intermittent hazing or loss of the vinyl’s surface shine. It is the result of the backside of the liner imprinting onto the face of the film. The pressure of the wound roll causes most mottling. Other factors that may contribute include exposure to heat softening the face, exposure to humidity expanding the liner or storing a roll horizontally creating pressure on the material.While mottling is aesthetically unappealing, it is not a surface or manufacturing defect. Remedy Mottling in installed graphics is normally removed with natural UV exposure. Prior to processing, mottling may be removed by carefully warming the film with a heat gun or releasing the tension on the wound roll and allowing it to stand for a couple of days. Prevention Material should be processed within its shelf life and should always be stored upright in a temperature controlled environment.