This video shows step by step how to use D/2 Biological Solution to clean a historic gravestone or monument. Sometimes the moss and mold on a historic monument can be aesthetically pleasing, so the first question is why even clean the monument? The simple answer is that the moss and mold are feeding on the stone and thus, actually destroying the monument. The next question to ask is whether the monument is in stable enough condition to clean. As you will learn in this video, the first rule of cemetery conservation and preservation is to do no harm. Enjoy! And let us know if you have follow-up questions.