A fine powder can occur on the surface of the paint film during weathering, which can cause color fading.
What Causes It?
The use of a lower-quality, highly pigmented paint or an interior paint can cause the paint to erode prematurely and cause chalking.
How to Solve It
Check for any remaining chalk by running a hand over the surface after it dries. If noticeable chalk is still present, apply a quality oil-based or acrylic latex primer (or comparable sealer for masonry).
Repaint with a quality exterior coating. If little or no chalk remains and the old paint is sound, no priming is necessary.
Note: Images provided by The Rohm & Hass Paint Quality Institute.