Planters provide an elegant way to display a variety of flowers and other plants around your home. However, planters made of decorative stone or brick are prone to leaking around the seams and joints. The water leaking out of these crevices is laden with minerals and other deposits that can cause stains. It's easy to prevent these issues by waterproofing the inside walls of your planter, so the water will only drain out the bottom as intended.
Clean all dirt and debris from the inside of the planter wall and allow it to dry thoroughly.
Brush water-based bitumen paint over the inside surface of the planter, keeping the brush strokes aligned in one direction. Allow the paint to dry for 30 minutes
Apply a second coat of paint. Brush it on in a direction perpendicular to the first coat, forming a 90-degree angle to the first set of brush strokes.
Wait seven days after applying the second coat of paint before filling the planter with dirt or potting material.
Test the planter's moisture level before applying the waterproofing material. Tape a clear plastic sheet over a section of the planter and turn it to face the sun directly for two hours. If moisture forms underneath the plastic, the planter is too damp to seal and needs to dry further. Water-based bitumen paint cleans up with water easily if it hasn't dried. White spirit are ineffective at cleaning this paint up.