I'm talking about painted on lume - Superluminova, etc.
This type of lume deteriorates with age, right? Some luminous paints are better than others, but old watches lose their lume, thus the requirement to reluminize if full lume performance is desired.
What is the root cause of this loss of lume?
Is it just time (age)? If so, then no matter how many hours the lume is outdoors in sunlight, or how many times it is "charged" with a flashlight or UV source, the lume will simply deteriorate with age. If this is the case, then we can "charge" our lume with reckless abandon and not worry about shortening its useful life.
Or is it usage? The more the lume is used, the shorter its life. If this is the case, then a watch stored in the dark should exhibit longer lume life than a watch which sees a lot of daylight or is otherwise "charged." If this is the case, then every time we "charge" the lume on a watch we are shortening the lume's life.
Does anyone know the aging mechanism for lume paints and which case above pertains?