headstone might sound pretty easy, grab a pressure washer, commercial stone
cleaner and go for it, But Wait!!!
You see, that just might be the worst thing you could possibly do to it, next
to sandblasting, and to do that to a hundred year old marble or limestone tablet
and you would be erasing away history, one detail at a time. The reason that
most early headstones, sculptures or heavily carved monuments are made from
marble or limestone is that they are a soft stone, making them easy to cut,
carve and finish.
Marble and limestone start out being a soft stone, add on a hundred or so years
and it becomes fragile, this is due to the loss of minerals from the surface by
weathering, organic growth and/or inappropriate cleaning.
These stones are usually so fragile that your can scratch them with your
So when it comes to cleaning, using a pressure washer will produce a disastrous
result. The high pressure will dislodge the soft minerals on the surface and
leave gouges that are destructive to the historical façade and often quite
noticeable, in a negative way.
Another thing to know about this “porous crust” on the stone, is that it
contains the patina or what some people would call the authentication of age.
This discoloration of the minerals on the surface is due to oxidization over a
long period of time.
This coloration is the historic patina of the stone and should always be
preserved and not removed during the cleaning process. Proper preservation
comes down to knowledge, knowledge of history, craftsmanship and materials. like
knowing what to use and what not to use, house hold cleaners like bleach,
should never be used to clean headstones, it might be fine for the siding on a
house, but put it on old white marble and it will react with the stone and
cause yellow streaking to appear over time.
Harsh chemicals such as acids should never be used, they bleach out the patina,
as well as washes away a micro layer of the historical façade.
So the question that should always be asked is, “Will it do any harm”
And the answer should always be “no” it will do no harm, and if the
answer is ever yes, or I don’t know, the process or product should not be used
So, “Bright white” for 100 year old headstones is not the desired result you
want to be looking at.
Our goal at Ponsford is to clean away the dirt, debris and organic growth such
as fungus, moss and lichen from the stone and leave the clean warm historic
glow of an aged monument.
cleaning of this historic marble sculpture is a time consuming process and is
not performed in 10 minute with a pressure washer. But more like 4 -5 days,
each area is hand cleaned with soft brushes and biocide and then rinsed with
clean water, achieving our goal of retaining the historical patina and integrity
of the monument, as well as preserving history.