With a careful, gentle hand and a bit of elbow grease, you can refresh a headstone or grave marker making it easier to read and restoring some of the stone's beautiful finish as first created by the crafting stonemason.
Due to the natural ageing and weathering process, you probably won't return the marble or granite to its perfect original condition, however, cleaning gravestones can effectively remove dirt build-up, bird droppings, mould, and other organic growth. A 50-year-old granite gravestone most likely won't come back to new, nor should you want it to, appreciate that some of the stone's beauty is gained through the ageing process.
If the headstone or gravestone is showing signs of chipping, scaling or flaking, don't attempt to clean the stone you may add to the problem. Instead, call in a stone restoration specialist to carry out professional stone repairs. Cleaning at this stage can actually damage the stone further.
Different types of stone require different cleaning materials and methods. First, you will need to determine what type of stone the headstone is made from. Is it marble, sandstone, granite, travertine, or something else?
Easy does it, even though natural stone is seen as a very hard substance, using a rough approach when cleaning can damage or scratch the stone. Using metal brushes, harsh plastic scrubbing brushes, or metal scrapers is a huge no, no. These tools can permanently mark the stone damaging the original finish. With any tool, use a minimal amount of force, carefully building up gradually as needed.
Use soft bristle brushes and a mild stone cleaning solution (mild ionic soap or detergent ph neutral) working in a circular motion to gently remove dirt and dust. Wooden or plastic scrapers can be utilised to remove larger build-up such as bird poo or moss and lichen. Clean a full surface in one go (front or back of headstone, top or sides of the gravestone) to ensure consistency.
Different types of headstones require slightly different cleaning methods.
Avoid high-pressure cleaners or pressure washers, especially when cleaning aged stone, you could really damage the headstone finish. Modern headstones can handle very low-pressure cleaning, however, keep in mind that stone gets more character as it ages. Over-cleaning may cause you to lose some of the individual, natural features that time and weathering bring out in the stone.
Never use harsh chemicals on a gravestone they will cause erosion of the stone. Cleaning gravestones with bleach will break down the stone, this may not be evident straight away but over time damage will begin to show.
Keep the stone wet during cleaning. Some stone restoration experts advise cleaning from the bottom up so the dirt doesn't continually wash down marking the yet-to-be-washed area. Rinse the stone several times after cleaning to ensure all cleaning products are washed from the surface.
Check with the cemetery management or administration before carrying out any headstone cleaning or restoration work. Each cemetery will have individual rules regarding work carried out on the gravestones.
Be sure your stone is stable and safe to work on. Sometimes a memorial can degrade internally over time resulting in a brittle structure which can crack, break, or fall when cleaned.
Test the cleaning on a small, out-of-sight area first to ensure it won't mark or stain.
Take extra special care when cleaning over delicate inscriptions, images, or photos.
Once you have cleaned the headstone or gravestone it should be good for another decade. If you are not getting the desired result after cleaning the headstone you may need a professional stone restoration to take a look at it.
References - chicora.org/cleaning.html, gravestonepreservation.info