Granite doesn’t need painting or sealing every year — but without basic care, even the best stone will eventually be covered in moss, algae and a grey film. We show you what to clean a gravestone with so you don’t damage the sandblasted inscription, and what to never use.
Why Does Stone Get Dirty and Turn Green in the First Place?
A gravestone stands outdoors all year round — rain, moisture from the ground and shade from trees are ideal conditions for moss and algae. This doesn’t mean the granite is of poor quality. Even the hardest Swedish granite or Impala will eventually develop a film if no one cleans it. The problem builds up faster on gravestones in the shade, close to hedges, and on pet plots, where slabs often sit lower, closer to damp ground.
What to Clean Granite With — and What Never to Use
- Water and a soft brush — the basics. Enough for regular cleaning every few weeks.
- Washing-up liquid diluted in water — removes greasy dirt and the first signs of grime, with no risk to the surface.
- Specialist natural stone cleaners — for stubborn moss or black algae stains. Only buy products described as safe for granite.
- Never: vinegar, hydrochloric acid, bleach, a pressure washer used too close. Acids damage the polished surface and can permanently discolour the stone. A pressure washer used too close washes the fill out of a sandblasted inscription.
Important for sandblasted inscriptions: sandblasted letters are recessed into the stone and filled with paint — scrubbing with a hard metal brush removes that paint and weakens the inscription’s readability for years to come. Use only a soft sponge on the inscription itself.
Is It Worth Sealing the Stone?
Polished granite is practically non-absorbent by itself — this is one reason we choose it for gravestones instead of sandstone or limestone. A sealant makes sense mainly on matte or flamed surfaces, where porosity is greater. If you buy a slab from us, the technical description will tell you whether a given granite needs sealing — most of our work doesn’t need it.
How Often to Clean a Pet or Human Gravestone
A check two to three times a year is enough: in spring after winter, in summer when moss starts growing, and in autumn before the first frosts. Stone that’s frozen with a layer of moisture and dirt is at risk of micro-cracks during freeze cycles — regular cleaning is, in practice, also protection against damage.
Frequently Asked Questions
Does black granite get dirty faster than light-coloured granite?
Not faster, but more visibly — on black Swedish granite, every bit of grime and every fingerprint shows up with more contrast. Light-coloured granites (e.g. Strzegom) mask small dirt better, but it’s also harder to spot the first signs of moss on them.
Moss came back a month after cleaning — what am I doing wrong?
That’s normal for gravestones in the shade or close to a lawn — moss regrows from spores in the air, and it can’t be removed “once and for all.” Products with a biocidal ingredient (not just cleaning agents) extend the interval between cleanings.
Can I clean a freshly installed slab the same way?
Yes, but wait at least two weeks after installation on a support wedge (Installation 1) — during that time, the masonry silicone and mounting tapes need to fully cure.
Have questions about caring for a specific granite from our range?
Write to us — we’ll advise which product suits your model, before you apply anything to the stone.