How do I clean a stone on my own safely? - Tennessee Memorials
First mix up a 50/50 solution of bleach water. Use a clean soft bristled brush to scrub the stone while applying the solution. Never let the bleach water dry on the stone or it may leave a white coating that is hard to get off. Just simply rinse with clean water after you have removed the desired amount of lichen. You can repeat this process to remove more lichen if it is more severe.