I have been painting for decades but I have always had a problem with "shadows". They are seen on the ceilings but are not noticeable at all on the walls which I assume is due to the different angularity of the surfaces.
I suspect but don't know for sure that the problem is due to the very quick drying time of today's paints. I'm guessing that when it comes to painting an overlapping section, that section has already dried out and that overlapping sections come out slightly differently from non overlapping sections.
Does this make sense? If so, how do I alleviate this problem? Is it possible to slow down the drying time of paint?
The newer paint formulations with low or no-VOC's will dry fast to the touch, but they will cure slower than paints in the past (especially heavily tinted colors). These products may be extended with water, or with some Floetrol to provide some open time.