Every cemetery in Southern Maryland has the same problem: headstones that haven't been cleaned in years, sometimes decades. Lichen colonizes the north-facing side. Air pollution and pollen darken the granite. Inscriptions that used to be sharp and legible fade under a layer of biological grime. Families notice. Cemetery associations notice. And the standard fix — a chemical biocide and a lot of patience — has real limitations.
Coherent Surface Technologies now offers headstone and monument cleaning using the same pulsed fiber laser technology we use for aerospace and automotive surface preparation. Here is why it is a better process for a lot of stones, and just as importantly, what it is not.
The industry-standard headstone cleaning product is D/2 Biological Solution, a quaternary-ammonium biocide the National Park Service has tested and endorsed for removing algae, lichen, and mildew from monument stone. It works. It also works slowly.
D/2 needs 10 to 15 minutes of contact time just to loosen surface staining, and heavy lichen growth often needs a second treatment weeks later. The full result develops gradually as the biocide keeps working after the crew has left. It also only works within a weather window — above 40 degrees Fahrenheit, dry conditions before and after application. In a Maryland winter, that is a real scheduling constraint.
None of that makes D/2 a bad product. It is the right tool for a lot of jobs, and we are not here to argue with the National Park Service. But it is not the only tool, and for a lot of stones it is not the fastest or the cleanest one.
One visit, not three. A laser removes the soiling layer in real time — what you see during the pass is the finished result. There is no multi-week reveal and no follow-up visit because the lichen did not fully let go the first time.
No chemicals, no runoff. There is no biocide going into the ground around a grave and no rinse water carrying cleaning solution across the cemetery lawn. Independent life-cycle studies comparing laser cleaning to solvent-based methods show meaningfully lower environmental impact — no consumables, no wastewater, nothing to store or dispose of.
Laser cleaning of stone works through what conservators call cold ablation. Each pulse is so short that the surface temperature only rises a few degrees, and the beam is absorbed by the dark soiling layer far more than by the lighter stone underneath. In practice, that makes the process self-limiting: once the grime is gone and bare stone is exposed, there is nothing left for the laser to absorb strongly, so it stops removing material.
There is no wire brush, no pad, and no physical contact with the stone at all, which matters most on engraved lettering. A stiff brush or a pressure washer can round off crisp edges that took a stone carver real skill to cut. A laser does not touch the surface.
We are also not weather-locked the way a chemical application is. There is no 40-degree floor and no requirement for a guaranteed dry window before and after. That is a genuine scheduling advantage in a region where the chemical-cleaning season is shorter than most people assume.
This is worth being direct about: Coherent Surface Technologies is a cleaning company, not a monument repair company, and we are not going to blur that line to close a sale.
We clean soiling, biological growth, staining, and pollution buildup off of stone that is structurally sound. We do not:
Those are jobs for a monument company or a stone conservator. They involve different materials, including lime-based mortars, different skills, and different liability than cleaning does. Most cemeteries have strict rules about who is allowed to perform structural work on a marker, and a well-meaning cleaning crew that starts fixing things without that expertise can cause damage that costs a lot more than the original stain.
If we get to a stone that is cracked, unstable, severely eroded, or otherwise showing signs it should not be touched at all, we will tell you that up front, including when the honest answer is to call a conservator instead of taking the job.
A headstone is private property even when it stands on cemetery land. We do not clean anything without written permission from the family, the cemetery office, or both, depending on the site. That is not just good practice. In several states, cleaning or altering a marker without authorization carries real legal penalties.
We are launching this service focused on granite markers, the most common material in modern cemeteries and the most durable substrate for laser cleaning. Marble and limestone are more sensitive to wavelength effects and can discolor if the process is not dialed in correctly, so before we take on a marble or limestone job, we test on an inconspicuous area first. We would rather turn down a job than risk a family memorial.
Coherent Surface Technologies is based in La Plata and serves Charles, St. Mary's, and Calvert counties, home to a lot of colonial-era, Civil War-era, and veteran burial grounds that have gone years without proper care. If you are a family looking to restore a marker, or a cemetery association looking at a maintenance backlog, we would like to talk.
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