Tina Marie, Where is the Irish cem. you are writing about ? Your local Genealogical or Historical Society may supply eager volunteers. It sounds like fun to me. The first time I tried to photograph a moss and lichen covered granite headstone, I couldn't read most of the inscription. Using what I had on hand, water and a rag, the crusty, grey growth just slid off the headstone, leaving dark stain on the lettering. It was perfect. The patina on the granite was not lost by cleaning agents or rough scrubbing. A soft brush might be good to have, but used cautiously. I believe very old buildings are cleaned with just water. It is so great you are doing this. Diane