Exposure to UV light causes pigments and dyes in toner and ink to fade. The amount of UV light exposure will have a direct impact on the amount of time before a toner fades. Generally, toners should have better fade resistance than inks. Only the manufacturer of the toner knows the actual pigments or dyes used in the formulation. Manufacturers many not know the fade resistance of their toners unless they have them tested in a fade chamber that simulates exposure to sunlight. The PIA Paper & Ink Lab has a Q-Sun Xenon Test Chamber for fade testing.