Covering water stains

[msweig]

I've got a few areas in the house where I want uod like to touch up some paint, or paint an area. I've touched up paint before and have generally never had any problems. Except for one area with some water stains.

The one time I tried to fix this area I put down a layer or two of Kilz first, then painted over it. I think the stain eventually bled through as it is noticable now. My understanding was that Kilz is pretty good (I was using the oil based one), so I'm guessing I did something wrong. For background the stain is on an area that is kinda like a windowsill (has firebricks as a window, with a ledge in front, which is where some water pooled).

It is possible that I'm incorrect on the stain bleeding through, and maybe there was some water damage afterwards. I know I've had a couple things done on that part of the house dealing with the leak, and maybe I'm recalling order of stuff incorrectly. Either way I'd like to try again, and figured best to ask then try , as opposed to try, fail, then figure out I was doing something wrong and have to try again.

On another note, what actually blocks the stain? I noticed that one of the two big companies that seems to make product for this is Zinssler, who also is known for shellac stuff, and am just curious if shellac has something to do with sealing the stain?

[EightFingers]

I don’t think firebricks should ever be used for a windowsill as they are too porous.
Maybe that’s the problem?

[msweig]

Sorry. Poor description. The window is firebricks. Then there is a ledge in front of them that appears to simply be drywall. A better way to describe it might be that the firebricks are recessed into the wall.

[K. L. McReynolds]

The shellac based Zinnser is better for blocking water stains. Providing the cause of the stain is remedied.

[vernonator]

A pic would be helpful. If its simple staining on drywall I have been very successful using a dilute mixture of bleach (10%) and water. Just give it a mist and let is sit and the water stain will vanish. Deep stains may take a couple applications. We had a few water stains on the ceiling of our last house and I used this on recommendation of a painter that was doing some other work for us. Worked like a charm and saved repainting the ceilings.

[Snipe Hunter]

Hard to cover water stains with water based paint or primer. I have a stain on the bedroom ceiling. I've probably got 4 coats of primer on it and it's still there. I've got a can of white based lacquer which I think will hide it, that's my next move. . There's some other repairs I need to do on that ceiling so I intend to repaint the whole thing anyway.