Cause:
Checking paint occurs due to the natural ageing of a suface, usually when there are several layers of oil-based paint. When the painted surface (most likely wood) contracts and expands as time goes on, the paint moves and gradually loses its elasticity, resulting in checking.
Solution:
If you want to repair the checking on one of your painted surfaces, you’ll first want to remove the existing layers of paint and thoroughly sand the area. Once this has been completed, prime the surface accordingly with a quality primer, and then repaint with a high quality paint.