Most headstone damage in this country is done by families trying to help.
That is not a criticism of anybody. A grave that looks neglected is upsetting, the impulse to scrub it is entirely natural, and nobody is ever told that the obvious tools are the harmful ones. But stone damage is permanent, and a great deal of it comes from a bottle of bleach and good intentions.
Here is the safe way, which is also the easy way.
Ask first, in two cases
If the memorial is not yours. Only the holder of the Exclusive Right of Burial can authorise work on a memorial in a council cemetery. Cleaning a relative's grave is unlikely to trouble anybody, but a stranger's is not yours to touch.
If the stone is old, listed, or in a churchyard. Historic memorials and anything in a conservation setting can be subject to real restrictions, and cleaning can count as an alteration. Ring the parish or the burial authority. They will usually say yes and may tell you something useful about the stone.
And if it is a Commonwealth War Graves headstone, do not clean it. Those are maintained by the Commission, and if one is damaged or obscured they want to be told rather than helped. That and other rules are in our guide to war graves and remembrance.
What not to use, and why
This list matters more than the method.
- No bleach or household cleaners. Bleach leaves salts in the stone which draw moisture, migrate to the surface and crystallise, breaking it up from within over years. The stone looks brilliant for a fortnight and worse than before within a few winters.
- No acids, and nothing descaling. Limestone and marble are calcium-based and acid dissolves them. Vinegar and lemon juice count.
- No wire brushes or wire wool. They scratch the surface and leave iron particles that rust, staining the stone orange permanently.
- No pressure washers. The most common cause of serious damage. Pressure strips the weathered outer surface from softer stone, blasts out the lead or paint in lettering, drives water into joints where it freezes, and can shift a memorial on its base.
- No scouring pads or scrapers. Anything that would mark a kitchen surface will mark stone.
- No sealants or polishes, unless a mason has specified one. Sealing traps moisture inside stone that needs to breathe.
- Not in frost. Wet stone in freezing weather is the classic way to crack a surface. Wait for a mild dry spell.
What you actually need
- Clean water, and plenty of it
- A soft or medium natural or nylon bristle brush, and an old toothbrush for lettering
- Soft cloths or sponges
- A plastic scraper at most, never metal
- Patience, which does most of the work
That is the whole kit. Water and a soft brush will handle the overwhelming majority of what is on a headstone.
The method
- Check the stone is sound first. Push gently. If it rocks, moves, or has open cracks or loose sections, stop and tell the burial authority. Memorial stability is a genuine safety issue and cleaning is not the priority.
- Clear the base. Cut back grass and lift leaf litter away from the bottom edge, where damp and growth concentrate.
- Wet the whole stone thoroughly and let it soak for a few minutes. This lifts a surprising amount on its own and stops dirt being ground in.
- Work from the bottom upwards. This is the one counterintuitive step and it matters. Dirty water running down a dry lower section leaves streaks that are difficult to remove. A wet lower section does not stain.
- Brush gently, in small circles, rinsing the brush often. Let the water do it rather than the pressure.
- Use the toothbrush in the lettering, carefully. Lettering is where the detail is and where damage shows most.
- Rinse thoroughly, from the top down, until the water runs clear.
- Stop before it is perfect. This is the hardest instruction on the page. Stone that has been outside for forty years is not going to look new, and the attempt to make it look new is what causes damage.
Lichen, moss and green growth
The commonest complaint, and the one where people reach for the strongest thing in the cupboard.
Never scrape lichen off dry. It grips into the surface and comes away with stone attached. Soak it thoroughly, leave it, soak it again, and brush gently. Repeat visits do more than force.
For heavier biological growth, conservation bodies generally specify a proprietary biological masonry cleaner rather than anything from a supermarket. These are designed to be pH-neutral and salt-free, and they work slowly over weeks rather than instantly. If you go this route, check with the burial authority first, follow the instructions exactly, and test on a small area low down before doing the face of the stone.
One dissenting note worth hearing. On genuinely old memorials, lichen is often considered part of the character and is sometimes protected, and some churchyards would rather you left it. If the stone is Victorian or older, ask before you start.
By material
Granite, including polished black. The toughest and the most forgiving. Water and a soft cloth. Do not use anything abrasive on a polished face, because dulling is permanent.
Marble. Soft, and acid-sensitive. Water only, gently. Marble also yellows and sugars with age, and neither can be reversed by cleaning.
Limestone and sandstone. Porous and soft. Very gentle brushing, and avoid soaking a badly weathered stone repeatedly.
Slate. Usually crisp and durable, but it can delaminate in thin sheets at the edges. Brush lightly and never lever at a flake.
Bronze and brass plaques. A different job entirely. Wash with water and dry thoroughly. Patina is protective, so removing it is a choice rather than a repair, and polishing a bronze plaque commits somebody to polishing it forever.
Lettering that has lost its paint
Cut lettering is often filled with paint or lead, and it fades or falls out over decades. It is one of the main reasons an old stone becomes hard to read.
This is a mason's job, not a home one. Repainting inscriptions freehand goes wrong easily, the wrong paint traps moisture, and overpainting onto the stone face is very difficult to correct. It is usually inexpensive to have done properly, and most masons will quote for it as a small job.
How often
Once a year is plenty, and gentle annual attention beats occasional heavy scrubbing by a wide margin. Growth that is removed yearly never establishes; growth left for a decade needs force to shift, and force is what causes harm.
If there is a memorial plaque on the stone, the same applies and it is even simpler. Warm water and a soft cloth once a year removes the algae that causes almost every scanning failure. No wire wool, no bleach, no pressure washer, for the same reasons as the stone itself. There is more on what outdoor weather does to plaques and codes in the durability guide.
When to call a mason instead
- The memorial rocks, leans or has moved on its base
- There are cracks through the stone, or sections coming loose
- Ironwork set into the stone is rusting and swelling, which splits stone from inside
- There is heavy staining you cannot identify
- The lettering needs recutting or repainting
- It is listed, historic, or you are simply unsure
A BRAMM or NAMM registered memorial mason will look at it and quote, and most will tell you honestly if it needs nothing.
The general rule holds well: the gentlest thing that works is the right thing, and stopping early is better than going too far. Stone is patient. It has already outlasted a great deal and it will outlast the rest, provided nobody attacks it with a pressure washer.