The most common question we get about cleaning is why it takes three visits when the stone is right there and the solution is already in the truck. The short answer is that the work is mostly done by the solution, over weeks, and not by scrubbing.
What is actually on the stone
What looks like dirt is usually alive. Lichen, algae, and moss are organisms rooted into the pores of the stone, not a layer sitting on top of it. This is why wiping a stone down accomplishes so little, and why anything abrasive enough to remove growth mechanically is also abrasive enough to remove stone.
Left alone, that growth does real damage. It holds moisture against the surface and its root structures work into the stone, which is what turns a cosmetic problem into an erosion problem over a few decades.
Visit one: assessment and first application
We check the stone's stability before touching it — older slate and marble markers can be loose in the ground, and a stone that needs resetting needs that addressed before anything else. Then the surface gets a gentle rinse and the first application of a biodegradable, pH-neutral biological solution: the same class of product used on national monuments and military cemeteries.
The stone will not look dramatically different when we leave. That is expected.
Between visits: the part that does the work
Over the following weeks the solution kills the biological growth, and normal weather does the rest — rain and wind carry the dead material away gradually. A stone will keep lightening noticeably for a month or more after an application. Families who see the site a week after visit one and a month after visit one often describe them as two different jobs.
Visits two and three: reaching what the first pass missed
The second application targets what the first did not fully penetrate — heavier growth, deeply carved lettering, the shaded north face, the base and footstone where debris collects. The third is a finishing pass and a final assessment.
Three is a minimum rather than a maximum. A stone that has gone thirty years without care may need more. We will say so rather than declaring it finished on schedule.
What a realistic result looks like
A properly cleaned stone looks like a well-kept stone of its age — not like a new one. Decades of weathering do not reverse, and a marker from 1840 should not come out looking like it was set last year. Where lettering has genuinely eroded, cleaning makes it more legible but does not restore what is gone.
What does change is substantial: the biological growth is gone, the surface is no longer holding moisture against itself, and the stone is protected against a fast return. That last part is why the first cleaning is the foundation of any ongoing care plan — maintenance visits afterward are upkeep rather than starting over.
What we never use
- Pressure washers — drive water into the stone and erode the surface, taking carved lettering with it.
- Wire brushes — scratch polished granite and shed metal fragments that rust into the stone.
- Bleach, vinegar, and household cleaners — deposit salts that keep working inside the stone long after rinsing.
Every one of these produces a faster visible result and permanent damage. If someone offers to fully restore a heavily grown-over stone in a single afternoon, one of these is how.