Let me preface this post by stating that my hard copy of "Preserving Gravemarkers in Historic Cemeteries", Brief #48 a 20-page publication by the National Park Service, arrived in my mail this past Saturday.
I can attest that it is definitely well worth the small investment amount to purchase it -- $6.00! Free shipping from the U. S. Government Book Store!
This expertly researched and presented publication is available online in PDF version, which is also great to save and access at any time. However, if you are anything like me (who is "old school"!) having an actual publication in book or booklet form, printed on good stock paper, is a thing of joy to hold for serious reading or even paging through for casual browsing.
So, I can recommend this great publication as a helpful addition for anyone's home library collection on the subject of gravestone conservation and cemetery preservation. The booklet offers a great start for learning more on this subject, or perhaps answering some lingering questions about it.
You won't find a better value for your money on the subject of preserving gravemarkers from any source!
The NPS (National Park Service) and NCPTT (National Center for Preservation Technology and Training) know this subject well!
NCPTT hold hands-on training sessions for gravestone conservation and cemetery preservation. Many who have attended these hands-on workshops have become professionals with this work and earned great respect in their field if they keep to the principles they were taught.