There are two headstones in Devon which I went to see a couple of years ago. One of the stones in question had a beautiful rose bush right in front of it, and the stone itself was covered in lichen. In spite of all the obstacles time and nature presented, I was able to obtain the details without adopting any harsh methods, which of course I wouldn't even think about doing. Although I do confess to having used water in the past.
The other stone - in the same churchyard in Bere Ferrers and opposite the main one - was completely illegible. However when the sun moved position what was invisible became wonderfully clear.
Jayson