Even weak daylight rays will slowly but surely fade the inks in a photograph or print by "bleaching" the colours unless you have conservation picture framing glass.  All light contains ultraviolet or "UV" rays and most picture frames are glazed with ordinary, clear picture framing glass. This type of glass blocks only about half of the UV rays and will not conserve colours or prevent fading. To retard fading, as absolute prevention is .. almost impossible, ask your picture framer to use"UV" filtering glass While this ...