The quickest way to make an old gravestone look clean is also the quickest way to destroy it. When the National Park Service took a conservation workshop to three Puerto Rican cemeteries in June 2022, it found the same lesson waiting at each one in a different form: the modern fix — acid, vinyl paint, hard cement — works at once and fails soon, while the older, gentler material lasts.
Why Puerto Rico, and why then
The work began as part of the federal response to Hurricane Maria. The Department of the Interior's Natural and Cultural Resources Recovery Support Function asked for help stabilising the island's gravesites, and a partnership formed between FEMA, the Department of the Interior, the National Endowment for the Arts, the National Park Service, Puerto Rico's State Historic Preservation Office and the Instituto de Cultura Puertorriqueña. An online course on the theory and practice of gravesite preservation came first, in 2021. Once COVID travel restrictions eased, the National Center for Preservation Technology and Training (NCPTT) ran hands-on workshops for municipal staff and preservation professionals in San Juan, Manatí and Ponce.
Three cemeteries, three problems
San Juan — acid. At the Cementerio Santa María Magdalena de Pazzis, tombs were being cleaned with bleach and muriatic acid. It works immediately, and it eats into marble and cast monuments, shortening the life it seems to restore. Soft cleaning methods were the lesson most urgently needed.
Manatí — paint. At the Cementerio Viejo de Manatí the problem was modern vinyl and plastic paint. It forms a barrier that stops water evaporating out of the stone, and the paint's own organic content grows mould. The workshop showed how to remove failing paint gently and prepare the surface for lime wash, and introduced the town to a supplier on the island who now sells it.
Ponce — earthquakes. At the Cementerio Católico San Vicente de Paul, earthquake movement had cracked large masonry monuments. The structural damage was beyond a workshop, but some stabilising techniques were not: broken marble plaques, some of them jigsaws of fragments, were reassembled and set in more stable positions — an act of repair and of remembrance. Participants also worked with lime mortar, using lime putty and natural hydrated lime bought for the purpose, to repair joints and stucco.
The rule behind all three
| Instead of | Use | Because |
|---|---|---|
| harsh acids and bleach | gentle cleaning methods and products | acid attacks the stone and leads to failure sooner |
| modern vinyl paint | natural lime wash | vinyl traps moisture; lime lets the stone breathe |
| hard modern cement | soft lime mortar | the repair should give way before the historic material does |
The principle is to find out what a monument was originally made of and repair it with the same. The gentler methods take more knowledge and skill, and sometimes more time and money at the start; what they buy is years of life for the material. NCPTT also recorded videos from the workshops — removing invasive plants, applying herbicides safely, and demonstrating what acid does to stone and masonry — so the techniques can reach people who were not there.
Sources
Written from the National Park Service / NCPTT report Gravesite Conservation (June 2022), a work of the United States government in the public domain. The project's partners were the Department of the Interior's Natural and Cultural Resources Recovery Support Function, FEMA, the National Endowment for the Arts, Puerto Rico's State Historic Preservation Office and the Instituto de Cultura Puertorriqueña.
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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