David asked: We have water stains on wallboard and batten. These stains got there from a leaking window, which has been replaced. The new window does not leak, but the brown stains don’t seem to get removed by a mild bleach solution. The wallboard and batten do not seem to be damaged, just discolored to a brownish color. It does not seem like mold either.
If your wallboard is unfinished, removing water stains will be all but impossible. You should avoid getting it wet, so most cleaning solutions are going to be out of the question due to the moisture content. If a mild bleach solution does not remove the brown marks left by water, your only reasonable option is to prime the wallboard with a quality primer such as Kilz, then paint. If the wall is already painted, and the water stains will not come off, you may still need to treat the surface with Kilz to block the stain from coming through a new layer of paint.