ageing

ageing (In French vieillissement) 1) Property of light sources to lose brightness with increasing service life, with its spectrum also shifting; bulbs and fluorescent lamps are more severely affected than LEDs, which is why the latter are being used more and more as steady standard light sources (see Just). 2) Long term process of chemical decomposition of layers of ink through external influences, e.g. solar radiation, rainwater, frost.