This YouTube video by Lady Taphos goes through the process of deep cleaning gravestones.
How They Get Dirty
These markers, usually made of marble, slate, or granite, receive the brunt of the outdoors. Excessive sunlight, strong winds, plus wind and snow erode the material.
Eventually, the gravestone’s composition becomes brown. Furthermore, mold could grow on its surface.
Some newer markers don’t have this problem. They’re coated with a gloss to protect the surface. On the other hand, older gravestones don’t have this extra layer.
Deep Cleaning Steps
1. Evaluate the gravestone to see if it’s wobbly or deteriorating. Cleaning might not be possible in this case.
2. Apply a biological solution that can remove the growth on the gravestone’s surface. Bleach or household soap may cause damage.
3. Leave the solution on the marker and add a little water to make it work.
4. Remove dirt or growths like lichen with a rubber scraper to avoid further scratches. Use a bamboo skewer to remove debris from the engraving.