Paint can lighten over time. This occurs on surfaces with sunny southern exposures.
What Causes It?
Fading or poor color retention can also be a result of chalking of the coating. One cause of fading is the use
of an interior grade of paint or lower-quality paint.
This can lead to a rapid degradation (chalking) of the paint film. Some paint colors are particularly vulnerable to UV radiation (most notably, certain bright reds, blues, and yellows).
Fading will also occur when tinting a white paint not intended for tinting, or overtinting a light or medium
How to Solve It
When fading or poor color retention is a result of chalking,
it is necessary to remove as much of the chalk as possible. When you repaint the surface, be sure to use a quality exterior house paint in colors recommended for exterior use.
Note: Images provided by The Rohm & Hass Paint Quality Institute.