Painting over water leak stains ? General decorating topics, questions and answers. find help, tips and advice on completing your decorating projects

[Brian]

The builder has finally repaired the kitchen roof and I can now repaint the ceiling. The water leaks have really left their mark in the plasterboard and I was wondering what preparation I need to do before applying paint. The ceiling plasterboard is sound but deeply stained in places and I believe I need to apply some sort of sealant prior to painting ?
If so, any recommendations ?
Thanks
Brian.

[stoneyboy]

Hi brian,
I use zinsser bin but it does need at least 2 coats and you will get high on the solvent in an enclosed space. Some of my colleagues prefer oil based undercoat, again two coats needed.
Regards S