What Is Chalking Paint?
Chalking Paint means, the formation of fine powder on a painted surface; it occurs due to weathering action which can cause colour fading. Although some extended chalking is normal, excessive chalking is a bad sign.
Chalking consists high level of titanium dioxide and extenders. An initially chalking paint is visible in white and off-white patches and excessive chalking is indicated a certain amount of mould and dirt on the paint surface.

Generally Chalking is caused by exposure to ultraviolet and other forms of radiation or nuclear radiation.
Causes of Paint Surface Chalking
Using thinned consistency of paint.
Using cheap quality paint.
When the paint is overspreading at that time chalking problem is occurs,
Not proper sealing and priming of the porous paint surface.
Applying paint on the dirty surface.
Long term exposure to ultraviolet and moisture.
Coastal Environments, with salty moist air.