Water or mold stains on your walls or ceilings can be a real problem to get rid of. You paint over them even with the best of paints and they still show through. The only way to truly get rid of the stains is to clean off the mold with a mild bleach solution. Mix a cup of bleach to one gallon of water and use a sponge to clean the mold stained area. Once it is clean let it dry thoroughly and then paint over it with a stain killer or a paint with a stain killer in it. The stain killer will cover and seal the stained area so that it will not show through the finish coat. Paint over it with a good quality paint that matches the color already on the wall. After the first coat dries if it does not the area completely apply a second coat. The stain will not show through again.