What's the best way to clean a 45 year old head stone made of marble with lead letters .
I don't want to damage it just clean it up brighter
Never clean any headstone in the UK in winter, most absorb water and the cleaning could allow the water to be absorbed and freeze taking the face of the stone with it as the ice expands.
If you really have to clean a headstone in summer use clean water and a soft cloth, nothing else.
Avoid catching the lead letters with the cloth they are held in place with tiny pins on their back and can be damaged or pulled out and twisted very easily.
Cheers
Guy