Previous coat blistering

[Rubberball]

Hi, i took it apon myself to plaster my bedroom ceiling a while back and think i have done a pretty decent job. Just at the weekend past i got round to painting it, i gave it a coat of watered down emulsion with some pva added in before giving it a few coats of paint. After it dried i noticed the odd flaw in my plastering. i decided to sand the bits that were noticeable back then repaint them. However after painting the sanded bits the previous coat has blistered and cracked around the sanded bits.

Obviously i have done something wrong.

Any advice on how to remedy it ??. Sand it back again, pva it then recoat ???

 

[Zampa]

You didnt need the PVA and thats whats has also caused your problem.

Dont use it anymore, sand down the rough blistered areas, give them a coat of oil based undercoat, thinned slightly to avoid the brush marks and to soak into the bare areas, fill, rub down and touch up with ordinary emusion...(thinned a little to saok into the filler)

You'l probably need to re coat the whole ceiling again to cover up the patches.