You Must Prime! "Paint and Primer" in one wil not work
I recently painted a living room that had a few areas were the paint was failing. One area was much worse than the rest. For this I followed my typical procedure. I got rid of all of the loose paint. and then put some spackle on area that had no paint. I must note that spcakle is really not designed for this purpose. It is more of a hole filling product. If I had more than one area that needed attention then I would have used joint compound to skim coated. But, when you want a quick turn around, on a small job, I find that spackle works well. I use the spackle to obtain a smoother appearance. Once the spackle was dry, I sanded the area. When I did this more of the paint came loose. So, I once again took off the loose paint and used the spackle. This time I used a hair dryer to speed the drying time of the spackle. When I used the dryer, paint on the area below the patch was flapping (like in the wind).....more loose paint! What was going on? I looked at a piece of paint and found that the back of it was not white. This indicates that the walls were not primed before they were painted. Sometimes painters use tinted primer, but this was not the case.
So, the only real solution to the problem is to take off all of the old paint, fix any imperfections that come with removing the paint, sand, prime and then paint. Most people do not want to pay for this to be done. I informed the home owner of what wad going on, and why it is happening. What I wound up doing is I put a coat of primer on the failing area, put some spackle over it, sanded and painted. It is not a perfect fix, and most likely there will be an issue in the future with failing paint.
The lesson is that there is not such thing as paint and primer in one. Primer is designed to have more grip to it than finish coat paints. If you have raw wood, plaster, blue board...ect., the best practice is to prime with an appropriate primer and then paint with a finish coat.