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Figure 13. The impervious
Avoiding 10
Common Maintenance Mistakes
1. Maintain records on conditions and treatments
of historic markers.
2. Seek advice from persons experienced with
preserving historic markers when initiating a
major maintenance or repair program.
3. Discourage visitor use of chalk, shaving cream,
and other materials to highlight carvings and
lett ering.
4. Train grounds crews in methods to avoid
damage to historic markers, including fl at
grave markers which can be easily damaged by
machinery, fertilizers and weed killers.
5. Remove graffi ti as quickly as possible, using
appropriate methods, so as not to encourage
further marker disfi guration and vandalism.
6. Maintain ground cover around cemetery
markers to avoid surrounding dirt from splashing
back and staining grave markers.
7. Never use rotary grinders to resurface or
“clean” historic markers.
8. Avoid the use of coatings on masonry without
proper investigation.
9. Avoid high pressure water washing to clean
historic markers.
10. Repair rather than replace damaged and
deteriorated grave markers. For markers encased
in cement, leave any repair work to trained
conservators.
scratching and even cutt ing into softer stone and wood.
Generally, the use of chemical weed killers at the base of
grave markers should be avoided, especially if there is a
risk that the marker would absorb the chemicals.
Repointing masonry grave markers using Portland
cement mortars that are harder than historic mortars
often results in accelerated deterioration of the masonry
material. Mortar should be softer than the adjacent
masonry, enabling trapped moisture to migrate out, and
serve as the sacrifi cial material when cracking occurs to
relieve excessive stress. Problems also result when using
impervious “protective” coatings that can trap moisture
within the masonry, resulting in damage during wet/dry
and freeze/thaw cycles (Fig. 13).
8
coating used to “protect”
this sandstone grave
marker trapped moisture
within the stone,
eventually resulting in
deterioration and surface
loss. Photo: Fran Gale.
Figure 14. High-
pressure water washing
can damage grave
markers. The photograph
shows “wand marks” on
the headstones produced
by inappropriate
pressure washing.
Photo: Jason Church.
Harsh cleaning products and techniques can have a
detrimental eff ect on grave markers. Acidic cleaners such
as muriatic acid can dissolve minerals in many masonry
materials and can att ack metals. Alkaline cleaners, such
as bleach, are notorious for leaving residual salts that are
deposited on the surface (a process called effl orescence).
Both acidic and alkaline cleaning can result in staining,
especially if rinsing is inadequate. Using high-pressure
water, above 500 to 1,000 psi, can needlessly damage
materials as well, increasing their vulnerability to
weathering (Fig. 14). If the marker is fragile, even low
pressure water can be damaging. Techniques to avoid
include aggregate blasting with sand or other harsh
media and the use of power tools with abrasive wire or
NyloxTM brushes.
Pollution
Grave markers can be both visually and materially
aff ected by pollution. Most readily apparent is the
discoloration that takes place when airborne pollutants
are deposited on markers. Depending on the exposure,
how water is shed, and the marker material and
intricacies, discoloration on markers will usually appear
uneven and in streaks.