Cleaning a Gravestone

The first question should always be, “does this stone truly need cleaning?” Often people mistake the patina of age for “dirt.” They want marble stones, for example, to be as white as when originally purchased – and this is a tragic mistake. Not only does such aggressive cleaning cause irreparable damage, but it destroys the stone’s patina – and history – making it look like the stone was placed in the cemetery only yesterday. Moreover, the cause of much biological growth is the shade created by the dense foliage of trees that usually can’t – or shouldn’t – be removed from the cemetery. Consequently, once you begin a program of washing you find that you must clean the stones every few months. And every cleaning, no matter how gentle, has the potential to cause additional damage to the stone. So, you may decide that a soiled stone is best left in that condition. Some stains in porous stones cannot be removed. Do not expect the stones to appear new after cleaning.

Removal of Organic Materials

There are times when biological growth may be causing deterioration of the stone. In such circumstances it may become necessary to clean the stone. On smooth, stable surfaces, algae, lichen, and fungus may sometimes be easily brushed or scraped off before washing (always use scrapers that are softer than the stone, such as wood popsicle sticks or bamboo skewers). Most surfaces, however, require wetting the growth before gently brushing, prying, or scraping them off the stone. Plants should be gently pulled out of cracks or clipped, and then the soil or debris they were rooted in should be brushed away from the stone. The plant's root system should be removed with the soil and debris. If there is a mass of plant life, don't just yank it from the stone or you'll almost certainly damage the stone. Carefully clip or pull away each section, to prevent pulling away any loose or weakened fragments of stone.

Materials Needed For Cleaning a Gravestone

Soft-bristle brush: Metallic brushes are entirely too harsh, and they also leave particles on the surface of the stone that can rust.
Small, soft, slanted paintbrush: To clean debris and critters out of lettering or carvings.
At least one large sponge, firm toothbrushes
Water: A good water supply, a hose connection, or buckets of water. You may also want to bring a small spray bottle of water for gently cleaning dirt and debris from the stone. The spray bottle, should contain only water and not detergent or chemicals of any kind that would damage and further erode the stone's material. You might want to use Photo Flo, which is made by Kodak and used in photo developing. Mix one capfull per gallon of water. Wash stone with solution, then rinse stone with clean water. Use brush.
Towel or old rags: used to kneel on or clean polished granite stones. Launder the towels first, but do NOT use fabric softener. The softener will affect their ability to absorb liquids as well as cutting down on the "magnetism" for dirt and dust.
Hand cleaner: Bring along a sample size of antibacterial waterless hand cleaners or wipes.
Cutting Tool: Hand-held grass clippers, scissors or a retractable razor knife for trimming grass and/or weeds close to the stones. DO NOT use weed-whacker type trimmers as these can scar the stones. For site clearing/cleaning, a pair of pruning shears or hedge clippers is also helpful for brush that is too thick to rip out or cut with grass clippers, but not thick enough to bother with a chain saw.
Pencil and Notepad: to record information about the stone or cemetery location.

At the Cemetery

Before starting, all surfaces of the stone should be checked. If there is any question as to the stone's condition, do not attempt to clean it, as the surface could be irreparably damaged in the process.
Start with a test patch of your proposed cleaning technique on an area of the structure that is least visible.
The stone surface should be thoroughly pre-soaked with water.
Thoroughly wash with plain water the pre-wetted stone with natural, soft bristled (natural or nylon), wooden-handled brushes of various sizes. The use of plastic handles is not recommended, as colors from the handles may leave material on the stone that will be very difficult to remove. Wire brushes, metal instruments and abrasive pads may give you instant satisfaction but, if you clean with anything that is harder than the stone, you risk scratching the face of the stone and causing more damage in the long run. Be thorough.
Wash all surfaces. Scrub the stone from the bottom up to avoid further streaking and staining. Always watch carefully to make sure that none of the stone’s surface is eroding as you scrub. Rinse thoroughly, with lots of clean water.
Keep the stone wet at all times; really wet. Where a garden hose is not available, be sure to bring plenty of jugs of water and keep dousing the stone as you work and, most importantly, flush the stone well when done.
Remove bird droppings, dirt moss, lichen etc. from the stone if possible. This will insure clear and sharp copy. If lichen is a problem, you can scrape with a wooden or plastic scraper. Tongue blades or craft sticks work well. Also, inexpensive plastic putty scrapers from home stores work well. Remember, no metal. If you have any trouble getting any of these materials off the stone, STOP and be sure that you do not cause any damage the stone in your attempt to clean it.
If used, do not allow detergent solutions to dry on the stone while cleaning.
Some stains in porous stones cannot be removed. Do not expect the stones to appear new after cleaning.
Do not clean marble, limestone, or sandstone more than once every 18 months. These types of stone may occasionally be rinsed with clean water to remove bird droppings and other accretions. Granite can be cleaned as needed.

After Cleaning

Keep a record of the cleaning, including date of cleaning, materials used and any change in condition since last cleaning (such as missing parts, graffiti, and other damage). These records should be kept at a central location where the condition of the stone can be monitored over time.

Cleaning Don'ts

Wire brushes, metal instruments, abrasive pads (Scotchbrite, Brillo, Steel wool)
Acid or acidic cleaners (especially on marble or limestone!)
Household cleaners: soap (Ivory), detergents (liquid or powder), Borax, Clorox, TSP, Calgon, Fantastik, Formula 409, Spic and Span (or any other abrasive cleaner)

REMEMBER: The use of improper cleaning materials and practices can cause serious and irreparable damage to gravestones! Make sure the stone is stable before attempting to clean it - no flaking, delaminating, etc. There are some “cleaning” approaches that should NEVER be used on cemetery markers.

Use of bleach. Sodium hypochlorite (common bleach) contains salts that damage stone. Stone "cleaned" with bleach, upon careful inspection, reveals erosion and yellowing.
Use of acid cleaning. Acids on marble and limestone dissolve the stone, leaving an inappropriate glossy and crystallized looking surface. This damage cannot be undone and the use of acids is also dangerous to you and surrounding vegetation.
Use of sand blasting. This approach (even if "soft" materials like glass spheres are used) is very harsh and will dramatically abrade the stone surface. This has the potential to actually accelerate further deterioration of the stone.
Use of high pressure water. Water pressure over 40-50 psi has the potential to significantly damage any stone that isn't sound, increasing spalling and accelerating sugaring.
Recarving inscriptions. While not actually a cleaning technique, this is sometimes done to "improve" the readability of faint inscriptions. But it does irreparable damage to historic stones, destroying their original artistry and beauty -- and destroying the historic significance of the stone itself. There are other approaches if a family wants to ensure that the grave continues to be clearly marked, such as setting a new stone horizontal on the ground.

Cleaning Gravestones can be a tedious and difficult job. But, with the right knowledge and materials it is possible.