Paint jobs can go wrong and it is usually for the simplest of reasons.
Do I absolutely need to sand down before I paint?
Often I get asked this question and the answer is simple: Yes! Sanding or abrading the surface you are about to paint provides a strong basis for the paint to have something to hang on to.
When inspecting paint failures one of the most common is one coat failing to adhere to the preceding coat.
Paint will not peel off another paint because it feels like it, it peels off because because the person applying the top coat has failed to prepare the surface to be painted properly resulting in setting up the top coat to fail!
Sanding or abrading helps coats of paint to adhere properly to one and other, failing to take this simple step is planning for the paint to fail!