First, Do No Harm: A Guide to Historic Headstone Cleaning and Preservation

I spend a good part of my mornings walking the older sections of Maplewood. Section C, mostly. The Civil War interments are there, with their soft marble and lichen-spotted sandstone. You see a name worn nearly smooth by a century and a half of weather, and the first impulse is to want to fix it. To scrub it back to clarity, to make it sharp again. It’s a good impulse, born of respect. But it’s also a dangerous one.

The first and most important lesson in cemetery preservation is that our duty is not to reverse time, but to slow its effects. Aggressive or improper historic headstone cleaning can cause more damage in an afternoon than fifty years of rain and ice. Our work is stewardship, and that requires patience, the right materials, and a deep respect for the object itself.

Assessment Before Action

Before a brush or even a water bottle comes out, the first step is always a careful assessment. You must understand what you are working with. Is it granite, slate, marble, sandstone, or limestone? Granite can withstand more than porous sandstone, which can be scraped away with a fingernail. Look for the subtle signs of decay: flaking surfaces, sugaring marble, deep cracks, or a wobble at the base. If a monument is structurally unstable, cleaning is the last thing it needs. A leaning stone is a job for a monument specialist, not a groundskeeper with a bottle of D/2.

We have a rule here: photograph everything first. Take clear pictures from every side, plus close-ups of any inscriptions or areas of concern. This documentation serves two purposes. It creates a record for your archives, but more importantly, it forces you to slow down and truly see the condition of the memorial. It moves you from the mindset of “cleaning” to “diagnosing.”

The Gentle Art of Cleaning

When it comes to how to clean old gravestones safely, the guiding principle is to always use the gentlest means possible. Often, that means starting with nothing more than clean water and a soft, natural-bristle brush. Never, under any circumstances, should you use a wire brush or a pressure washer. A power washer, even on its lowest setting, will strip the fragile outer layer of an old stone, erasing details and creating a porous, damaged surface that invites faster decay.

For biological growth—the green, black, and orange stuff that thrives on stone—the only product we allow is a dedicated biological cleaner like D/2 Biological Solution. There is no substitute.

What to Use and What to Avoid

• DO: Clean water, soft natural or nylon bristle brushes, wooden or plastic scrapers for thick lichen, and a PH-neutral biological cleaner like D/2.
• DO NOT: Use household cleaners, bleach, ammonia, muriatic acid, or any other acidic formula. Bleach and other salts recrystallize inside the stone’s pores, essentially blowing it apart from the inside out over time.

The process itself is simple. Wet the stone thoroughly with water. Apply the cleaner according to the manufacturer’s instructions, usually with a low-pressure pump sprayer. Let it sit for several minutes. Then, gently scrub the surface in a circular motion, working from the bottom up to avoid streak marks. Rinse thoroughly with more clean water. The key is patience. A biological cleaner works slowly, and the stone will continue to lighten and improve for weeks or even months as the solution kills the microorganisms and the rain rinses them away.

The goal is not a new-looking stone; it is a clean, stable, and legible one. We are custodians, not restorers.

Beyond Cleaning: When to Call a Conservator

Most of our work should be limited to gentle cleaning. Cemetery monument repair is a specialized field. While resetting a small, flat marker that has shifted in the turf is often within a skilled cemeterian’s capacity, anything more requires a professional. Attempting to piece together a broken stone with hardware store epoxy or concrete can be a disaster. The repair material is often stronger than the stone itself, causing new breaks as the seasons change and temperatures fluctuate.

If you see deep cracks, delamination (where the stone is splitting into layers), or a break in a large upright monument, the correct action is to document it, perhaps brace it carefully if it poses an immediate hazard, and call a professional monument conservator. A bad repair is often worse, and far more expensive to fix, than no repair at all. Our responsibility is to the decedent and their memorial, and that means knowing the limits of our own skills.

This work is a quiet, steady practice. It connects us to the people who came before us and ensures their resting places endure for those who come after. It is less about scrubbing away the past and more about carefully tending to it, so it can have a future.