The National Movement for Tombstone Preservation

Over periods of time gravestones will tend to accumulate a considerable amount of dirt, mold and water spots. The practice of tombstone preservation is a commitment to conserving the quality of aging gravestones in an effort to maintain a loved one's resting place intact.

Clean grave stones with white nylon bristle brushes. A good example is a toothbrush. Nylon bristles are best for avoiding scratches, and the absence of dye in the bristles prevents unintended staining of the grave stone during cleaning sessions.
When using liquids to scrub grave stones always substitute calcium hypochlorite for bleach. Household bleaches contain sodium which is highly damaging to stone.

Finally, avoid tombstone rubbing. Rubbing refers to the act of placing a paper over the tombstone and reproducing the engraving on paper with pencil strokes. The practice of "rubbing" at a graveyard s is actually very harmful to the stone and is being banned by many cemeteries.

To better learn how to care for cemetery grave stones, consult a cemeterian or attend a preservation workshop, these are often offered to interested individuals by local cemetery associations and genealogy societies.