I'm painting the downstairs bathroom here at my home. I had a nice coat of salmon color flat latex on the walls from Home Depot I think. It had been on for about two months. The ceiling was flat ceiling white latex.
What I did was take some of the ceiling paint which was left over and tinted it with some of the salmon which was left over. I applied it to the top of the walls, about eight inches, so the ceiling wouldn't appear so high (its about a 10 foot ceiling) and to reduce the effect of the drastic change from the salmon wall to the white ceiling. Salmon is kind of pink.
The first coat was fine. The second coat filled with something like spider web cracks after drying. A third coat also filled with small cracks. I only put one coat of the new mixture on the ceiling and had no problem with cracks.
I'm not going to fix this. Its only an eight inch strip around the top of the wall. But I would not want this to happen if I was doing it for a customer. What gives ?