Zinsser 123 primer/sealant pealing off bathroom ceiling

Hi. Ive had a leaf through the previous decorating questions hoping to find your origional question without luck? I hoped i could understand the problem better. As regards advice to use zinsser bulls-eye 123 then that was technically correct. Checking in zinsser's guide to surface preperation, the category that nearest fits your description is 'friable/chaulky walls and ceilings'. They reccomend 123 , full coat and allow to dry. Id like to know what surface you were left with after scraping off? Previous paint layer? Filler? Bare plaster? The only reason i can think of that may be causing this issue is a contaminant. Bathrooms and kitchens after a while of use have contaminants on their painted surfaces, due to the steam created settling on the surfaces and leaving a residue , soap, grease etc. I always wash all these surfaces with a warm sugar soap solution followed by a clean water rinse. Although zinsser advise 123 for this i rarely use 123 ( good for priming wood trim) as a problem solver, i use zinsser b.i.n and always have some. Its a great allround stainblocker and primer esp on problem surfaces. Another option is zinsser permawhite, that also acts as a great primer but is also the finish coat, so 2 coats of pemawhite on a bathroom ceiling usually does the job.

bathroom needs to be dry before appleying paint to it and walls must be dry.