Hardly any other performance criterion of daylight fluorescent pigments is discussed more frequently than their comparatively low lightfastness (UV stability). Lack of lightfastness is the main argument advanced for discriminating against daylight fluorescent pigments in many outdoor applications involving permanent exposure to sunlight. The UV stability of fluorescent pigmented systems depends on various factors, such as colour, type and chemistry of the pigment and binder, pigment concentration, as well as the layer thickness and layer structure in the final application. While fluorescence can remain stable for several years indoors, it decreases very quickly in direct sunlight and outdoors. ...