Wall stains can occur due to the inadequate cleaning of a wall before painting or from dampness. This guide will help you block an existing wall stain.
Thoroughly clean the affected area using sugar soap and a cloth or sponge. Ensure the surface is fully dried before moving on to the next step.
Apply stain blocker to the surface of the stain. Again, allow this to dry completely before continuing onto the final step.
Recoat the affected area with spare topcoat from when the room was last painted. Once this dries, your stain should not be visible anymore.