Q. I have a very badly stained ceiling, the result of a water leak from the attic tank. I would appreciate if you could advise me how to treat the problem as the stain is still coming through. 

A. This is a fairly easy problem to fix. All you need is to apply an appropriate stain blocker with a brush and finish off with a coat or two of paint. These stain blockers come in various types, generally water based, oil based or alcohol based. The best type for water stains is the alcohol type, and next best would be the oil based. Note that a water based stain blocker is no good on water borne stains but would work well on oily stains. Its almost like opposites work best. There are a few types of stain blockers on the market and one of the better ones I’ve come across is a product called Seal Lock. (Tip: Seal Lock dries extremely fast and you might not be able to wash out the brush afterwards unless you have a supply of mentholated spirits)