Clearly Amazing utilizes a soft wash process for roofs, which safely and gently cleans without the use of high pressure or wire brushes. Therefore, all visible moss may not be completely removed at the time of service. The percentage of soft brooming estimated is the amount of moss that will be removed prior to applying our cleaning solution, which will then kill 100% of the remaining moss and its root system. Any dead moss will take three to six months to shrink away from the shingles and weather off naturally with the wind, rain and other elements. This deliberate process ensures a thorough cleaning without damaging your shingles.