Soft brush, clean water, a conservation-grade biological cleaner, and patience — that is the entire safe method. Everything harsher damages stone that cannot be replaced, which is why headstone cleaning follows conservation practice rather than cleaning instinct.
Assess before anything touches the stone
Sound stone can be cleaned; unstable stone must not be. Check for cracks, flaking, sugaring surfaces and any face that moves or sounds hollow when gently tapped — those markers need a conservator’s stabilisation, not a wash, and cleaning them causes the loss you were trying to prevent.
Marble and limestone are the delicate ones; granite is the most forgiving. If you cannot tell what the stone is or whether it is sound, photographs to someone who can beats guessing.
The method, start to finish
Saturate the stone with clean water first — a dry stone pulls cleaner deep into its pores. Apply a non-ionic biological cleaner formulated for historic masonry, let it begin its work, and agitate gently with soft natural or nylon brushes, never metal. Work from the bottom up to avoid streaking, rinse thoroughly, and stop.
No pressure washer at any setting, no scraping at lichen — kill it chemically and let weather release it. The inscription survives by being touched as little as possible.
Patience is the finish
A biologically cleaned stone keeps improving for months: the treatment continues killing growth, and rain gradually carries off the dead material. The six-month result routinely beats the same-day result.
Once or twice a decade is plenty. Every cleaning, however careful, is wear — the goal is the least intervention that honours the marker, not the brightest possible white.
Unsure whether a family stone is sound enough to clean? Send photographs — we will tell you honestly, including if the answer is leave it alone. Read more about headstone cleaning →