The real "skinny" on tombstones. I have read all the "dos" and "don'ts" regarding the best way to read old tombstone inscriptions. I certainly do NOT have the answer, but reading all the "don'ts" leads me to wonder about the scientific validity of some of them - like pencil rubbings, shaving cream etc. True anything CAN leave a chemical residue, including merely touching the stone with your hand. But, is there anything more harmful than the natural elements contained in the atmosphere? Are these "don'ts" based on real data or just passed down opinions garnered by someone else? If they are based on real data, please provide the location so I can go there and read it for myself.