How to clean granite headstones?
Determine the composition of the stone, if you're not sure. This article deals specifically with granite; the same techniques can be used successfully with other materials, but keep in mind that granite, being the hardest of the most commonly used materials, can stand a bit more aggressive approach to cleaning.
Inspect the stone for any damage, cracks, or flaking. Stones with damaged areas should be washed with care to avoid further damage.
If you find damage around the base of a new headstone, it may be from the cemetery's lawn care equipment. Document the damage with pictures and contact the cemetery for possible compensation.
Thoroughly wet the stone to start softening any material that is on the stone. The usual method of wetting a stone is with a bucket of water, but a small pump sprayer can save trips back and forth to the water faucet, plus gives you a clean supply of water for rinsing the stone. Small pump sprayers can be purchased at most hardware or rental stores and are relatively inexpensive. It may be something to consider purchasing.
Start scrubbing with just a soft brush and water. Much of the residue on the headstone can be removed with just water and elbow grease.
Mix the non-ionic soap according to package directions. Use this mixture if you find areas that are not responding to just plain water and a brush. Non-ionic soaps and detergents are pH balanced and will help to keep from damaging the stone.
Products to avoid are most household cleaners, detergents, and any abrasive cleansers that can scratch the stone. Stay away from bleach and ammonia as well. Not only can they damage the marker, but many of these household cleaners can kill the grass at the base of the headstone.
Also, stay away from shaving cream, which gets touted as a fantastic headstone cleaner. It is...it will remove almost any debris and stain from the marker instantly. However, the acidic cream leaves behind stone eroding chemicals that will speed the deterioration of the stone. Avoid the easy method and stick with elbow grease and non-ionic soap.
Stay away from metallic scrubbers as well for removing any organic material or bird droppings. For this part of the cleaning, plastic scra*pers are ideal. They are soft and flexible, get the job done and won't damage the marker.
Use the soft bristled brush to begin scrubbing the stone after the stone is wet and you've applied your cleaning solution. Use the plastic scra*per to dislodge any stubborn material. A soft bristled toothbrush can be used for carvings and lettering.
Conventional wisdom says to start at the bottom of the stone and work towards the top, to avoid discoloring the stone as dirty water drips over the unwashed areas. Unless your stone is very dirty, or the stone dries before you finish cleaning it, this usually isn't necessary.
Also, don't forget to clean the sides and back of the marker. It's easy to forget the back, since most markers don't contain any carving there, but it's just as important to clean those areas as the front.
Continue gently scrubbing the stone, and rinse frequently with clean water to remove soap and any debris that is dislodged. When you've finished cleaning the entire marker, rinse well again with clean water.
Wipe the headstone with paper towels or soft cloths when you've finished. It will keep the stone from streaking as it dries, and you can tell if you've missed any areas and need to spot clean them.
Read more: How to Clean a Granite Headstone | eHow.com http://funadvice.com/r/3k9n3gtk53
i got this from a website but i used to do this for a living so i know it checks out
How to clean granite headstones (or similar granite surface):
1) use a ph balanced cleaner - nothing with too much soap or too much acid, as it will damage the material.
2) your local hardware store eg, home depot lowe's, etc, will have special cleaning agents that are designed to clean granite surfaces. These are the same cleaners you'd want to use on headstones, countertops, or other surfaces.
3) make sure you're careful and don't use a product with vinager, etc, as it will damage the surface of the granite.
I have used Quick n Brite for years to clean headstones. It is a gentle concentrated cleaning solution with no chemicals so it will not harm the marble, granite or stone and it will not kill the grass or flowers planted around the headstones. Quick n Brite cuts throught the lichen growth and algae without chemicals that are harmful and dangerous for you to clean with.