Here is a stone that was repaired and replaced in its slot base. The stone was epoxied then the crack was filled with mortar to keep the rain out. The mortared crack is covered with wet towels and then wrapped in plastic to allow it to dry out slowly over three or four days. Drying time depends on the weather - the temperature and the humidity.
Here's a stone that will be used for a cleaning demonstration.
Pre-wet the stone with a dilute solution of water and CLEAR ammonia. Keep the stone wet during the entire brushing process. Some people use spray bottles, other use a bottle with a small opening. Wear work clothes!
Note the variety of brushes Walt has at hand. Wherever he goes (shopping with his wife) he's always feeling brushes for their stiffness. The stiffer the better. (Note: Some restorationists are opposed to the use of brushes, at varying levels of brushing. There are good arguments on both sides, but everyone should be concerned with the preservation of the stones.)
A pressurized sprayer help remove some of the grime.
Walt uses Nyalox brushes of drills. The (Dico) Nyalox brushes are synthetic and are impregnated with a range of abrasive grits. Nyalox brushes are typically used for surface preparation for wood, rubber, plastic, metal, masonry and concrete.
Here's a half-cleaned stone that shows the difference between a stone as it may have appeared when new and as found at the Crosson Cemetery.
Walt shares part of his vast range of experience with the assembled group.