Primed Plaster Ceiling Bubbling - Help Appreciated
We're in a big mess and could really use some good advice. We have a 50's era house with plaster ceilings. We started with the kitchen ceiling by washing and rinsing it. Then went on to prime it with latex primer and 2 coats of latex ceiling paint. When the last foot of masking tape was removed a chunk of ceiling paint came down with it. We realized that originally they must have used an oil based paint. We ended up scrapping the entire ceiling and then re-primed it. After the primer was dry realized it was bubbling in several large spots. At the time we noticed several large yellowed spots but thought the primer should cover them. We have now tried sanding the ceiling but it's absolutely grueling and discouraging. I'm ready to give up as we've now been at this project for a week straight.
What went wrong? Any solutions other than sanding the entire ceiling which I'm about to give up on. Putting new drywall over the plaster is out of the question as I cannot afford it. Any suggestions and help would be much appreciated. Thank you