The Do's and Don'ts About Cleaning Marble Grave Monuments

by Linda K. Lewis

Marble Monuments

It is absolutely NOT recommended to clean any marble or sandstone marker! It does damage to the stone when you use brushes and scrappers to get off the lichens - little bits of the stone come off with the lichens and even more is loosened to more easily (and quickly) erode. Marble stones only have an expected span of 50 years as it is. And if you do clean a marker, never clean it again - all you are doing is basically sanding off the outer layer and that outer layer is protecting the integrity of the stone.

First rap on the stone to make sure it is really solid and not ready to crack - you can tell. The weakest spots are usually in the middle of the inscription of the name. Never use soap, household cleaning products, Clorox, or ammonia on a stone. Just straight water - or you can add 1 oz Kodak Photoflow to 1 gal water. This helps defeat the streaking and has been certified by curators as safe. Soak the stone thoroughly through and through, then start at the bottom and work your way up. Serious and permanent streaking can easily occur otherwise. Keep water running on the stone the whole time and you can't wet it or rinse it too much. Use natural white bristle brushes. Do not expect you will end up with a sparkling white legible stone.

Professional curators often recommend removing the stone for professional cleaning. They place the stone in soaking water baths for months or even years before touching it. If you have paint or graffiti it is best to call a professional, some will work on site but there will be lasting damage that may or may not be visible at the time.

The Association for Gravestone Studies has cleaning recipes and several articles. This is a good starting point:  AGS FAQ page.

AGS also has a series of Field Guides. They have a field guide for cleaning, but it is not comprehensive. There is a field guide for recording a cemetery that would be good for a novice. The membership is full of professionals, curators, archaeologists, and students or groups performing scholarly studies, and advice can always be found there.

The biggest thing with photo/transcribing is light. Never put toothpaste or shaving cream on markers as they have oils that remain forever, even if you rinse it right off. Over time it may darken and promote growth. The AGS guide suggests the use of mirrors at different angles to reflect light and produce shadows on the stone. I also find that using plain water to soak the stone can help with some stones in certain circumstances. I have not found IR or UV photography to help at all, nor the use of blacklights, at least not with what I have here.

There are some stones - usually light gray granite with no darkening in the engravements - that defy getting a photo where you can read the entire inscription but you might be able to spotlight portions using angles and mirrors.

Granite Monuments

Granite stones can easily and safely be cleaned with water and brushes without concern to hastening the decay of the stone and the polished ones can look good as new again.

Metal Monuments

Some metal and bronze markers can be safely cleaned but be sure to know what the metal is first and use something appropriate.

There is white bronze (zinc) which looks like a marble stone and can be easily damaged with improper cleaning. Be careful here, the white bronze has a natural patina.