Cleaning Headstones

This page will explain different techniques and choices for cleaning headstones.

Is the stone cleanable?
If the stone shows signs of chipping, scaling, flaking or other forms of deterioration, do not
clean. You will do more harm then good.

Next, determine what kind of stone is it?
The type of stone can determine what technique should be used to clean it. Most common
gravestones are likely to be sandstone, slate, marble, limestone, or granite.

Regardless of what kind of stone you are cleaning, the first rule is always to be as gentle as
possible. Use the least aggressive approach, to accomplish the cleaning objectives desired;
safely without harming the stone. It may not be possible to clean the stone as thoroughly as
you had hoped before beginning the project.

Be flexible and relax your preconceived notions regarding what the stone will look like once
the cleaning operation has been completed.

Always begin with clean water, a soft scrub brush, and plastic scrapers. Completely saturate
the stone to be cleaned with water.

A pump sprayer works best for most gravestone cleaning operations. Home centers sell
various types with prices starting as low as $10. A sprayer will use much less water then the
old bucket and brush method.

Additionally the bucket method always returns the polluted water, still on the brush back into
the clean water thus contaminating it.

There are many different types of brushes which work well for cleaning cemetery memorials.
It is best to always have a wide range of brushes on hand, including multiple sizes, with
various stiffness, of the bristles. Always begin the cleaning process with the softest brush to
see if it will get the job done. Progress to stiffer bristles only if needed. Although mentioned
previously, I will repeat, do not use wire or metal brushes of any kind, as they may scratch
damage or stain the stone.

Suggestions regarding brush selection: Some conservators advise against using natural
bristle brushes, as they may leave behind residue which might increase future biological
growth. In a purest sense this may be true, and when conserving artifacts in a museum
setting, this may be good advice. Gravestones in an outdoor environment do not seem to be
effected by this extremely minor, possible residual effect, which natural bristles pose. On the
other hand, natural bristle brushes are often softer and more effective for many types of
stone cleaning.

Car wash type brushes work well for the softer end of the spectrum. Do not use old
contaminated brushes from previous non gravestone cleaning projects. Typical scrub
brushes are more aggressive and vary in size and exact stiffness of the bristles. Grout
cleaning brushes are very effective for getting into tight spaces, such as cleaning in and
around the inscriptions and carvings.

Always remember to rinse often as the cleaning progresses to monitor for flaking or scaling
to the stone.

I love to use plastic scrapers when ever possible to remove biological activity. Certain types
of growth can be removed quickly and effectively with only the use of plastic. They are
available from home centers and hardware stores at a very reasonable price.
Buy the package with a few assorted sizes. Not all plastic scrapers are formed from the same
quality and hardness of plastic. In many respects the softer the plastic the better.

Instead of damaging the stone, the plastic wears away fairly quickly.

Always scrub in a random orbit motion, to avoid streaking or erosion to the surface of the
stone. Many conservators make an issue to recommend starting the cleaning operation at
the bottom of the stone, working towards the top. This serves to avoid staining the stone from
runoff as the cleaning advances upward. I have found that with an average sized gravestone
or monument, it makes little difference where you start cleaning, provided you clean the
entire side once you begin. But, most importantly be sure to completely rinse off the stone
before it dries. Streaking and staining, may result if the dirty water is allowed to evaporate
before being rinsed from the stone.

A non ionic detergent is safe to use on nearly all types of stones encountered in Cemeteries
and graveyards. It has a neutral PH which will not effect or harm historic stones. A word to the
wise, don’t expect miracles to occur while cleaning with a non ionic detergent, you have to be
patient as results are often less then spectacular.

The problem with most cleaning products is they will only clean on the surface. Just like a
tooth, most biological growth has roots which take hold beneath the surface. A biocide will not
only penetrate the surface to reach the root structure, but it is the only product which will
inhibit future growth.

A major difference regarding the application of D2 is it may be sprayed onto a dry stone
surface. Within a few minutes it will go to work eating away at the biological activity. Be sure
to rinse off thoroughly before it dries, as described above.

Another highly effective cleaning method is to poultice the stone. This employs the concept a
capillary action to wick away staining safely. A poultice is simply a clay type substance whish
is placed on a pre moistened stone. The stone is then covered to avoid evaporation. Once
the stone is uncovered, it is rinsed clean of the poultice and hopefully the staining attempting
to be removed.
This is a very safe technique when properly employed, and may be performed on very
delicate surfaces. It is often used in museum environments.
Entire books have been published on cleaning stone and masonry. Historic Scotland has
published individual books for each major kind of stone encountered.

A short list of cleaning techniques based on stone type
Listed in order from the safest, or least aggressive, to the most aggressive:

Slate: Clean water, non-ionic detergent, biocide solution

Sandstone: Clean water, non-ionic detergent, biocide solution

Marble/ Limestone: Clean water, non-ionic detergent, biocide solution, ammonia and water
solution, Calcium hypo-chloride solution

Granite: Clean water, non-ionic detergent, biocide solution.

Modern Polished Granite: Clean water, non-ionic solution, biocide solution, Acid based
granite cleaning solution, include with links. It is most common in a dry crystal form and is
mixed with water to form a solution. Its strength may be varied based on the amount of
crystals added. Please be very careful, as eye protection and rubber gloves should be worn.
Also it may kill grass or plantings in the area around the stone being cleaned.

Unpolished Modern Granite: The same as polished. Additionally plain old fashioned cleanser
may be doing the best job of all. Comet or common dry cleanser without the extra cleaning
crystals works wonders when cleaning unpolished modern granite monuments. Do not use
cleanser on polished granite as it may scratch the finished surface of the stone.

CLEANING HEADSTONES