(Vicki’s Note – here are some practical suggestions from the United States Government on how to clean the Headstones and Markers that they issue free to military veterans. The procedures can be used on any marble cemetery headstone.)
Cleaning and Caring for Government Headstones and Markers
The National Park Service’s National Center for Preservation Technology and Training completed a study in 2011 to evaluate general cleaning needs of marble government-issued headstones. The findings are found in Best Practice Recommendations for Cleaning Government-Issued Headstones.