Use a Stain-Blocking Primer to Cover Flaws
Roof leaks, overflowing sinks, tobacco smoke and big spills can all leave ugly ceiling stains or dinginess that is impossible to conceal with plain old paint. But cover the stain with a coat of stain-blocking primer and your troubles are over.
The traditional favourite is white pigmented shellac. You can buy spray cans of pigmented shellac, but usually it’s easier to brush it on. Just don’t forget to pick up some ammonia or denatured alcohol to clean your brush. If you’re painting over a ceiling that’s yellow from smoke, roll a coat of shellac over the entire ceiling before painting with latex.