Things You'll Need
Instructions
Preservation
Assess the monument's setting and condition. Be mindful of impending or possible future threats to the monument. Restoration is dependent upon preservation, and any restoration will quickly become useless without making provisions to protect the monument from the elements and human-induced damage.
Look for evidence of ground settling, overgrown vegetation and water-runoff. All of these situations will threaten the lifespan of the monument. Also look for potential future problems such as nearby dead trees with overhanging limbs that could fall and break the monument.
Avoid mowing too close to the monument. Particularly in cemeteries, grave markers are susceptible to damage from being run into by mowers. Use a nylon-stringed trimmer near the monument.
Cleaning
Clean gently. A proper cleaning will "restore" many of the features of the monument hidden by decades of accumulation of grime, algae, fungi and other materials. Do not attempt to clean a stone monument in an unstable condition (a flaky surface is a good indication of an unstable stone monument).
Begin cleaning by removing loose debris with a soft-bristled brush. Again, only brush the surface of a stable monument, and stop if the stone or the monument's material is also brushing away.
Wet the monument with plain, clean water and brush again. Do not use a brush with wire bristles. Have a pail and rubber gloves at hand.
Use a weak cleaning solution if necessary. Orvus detergent is probably the least likely to cause damage to the monument's surface. Ammonia can be used on marble.
Restoration
Reset monuments that have sunken into the ground, but first have a plan ready for temporarily moving the monument as safely as possible. Do not reset monuments in concrete, as they will be more susceptible to snapping off at the concrete's surface.
The Graveyard Preservation Primer recommends using a dry-laid area of stone or brick for a base. Then add a mixture of sand and gravel for drainage, and fill with firmly tampered soil.
Hire a professional mason conservator to make any repairs. The Chicora Foundation notes that amateur-attempted repairs will cause more harm than good. Avoid using commercial products, such as epoxies, that promise easy results.
Seek recommendations for a qualified professional from the state historic preservation office, local museums, monument preservation firms, and monument manufacturers. Large cemeteries with a professional staff are also good places for advice.