Treat a wet gravestone with D/2 Biological Solution, scrub into a lather using a plastic bristle brush, and smooth the lather into the inscription to make the letters more readable. Afterward, rinse the stone thoroughly.
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Why can't I use
shaving cream to highlight inscriptions on difficult to read
stones?
Our professional conservators tell us it is
definitely not a good idea to use shaving cream on porous
gravestones because there are chemicals and greasy emollients in
shaving cream that are sticky and very difficult to remove from
the stone with a simple washing. Indeed, even with vigorous
scrubbing and lots of rinsing, the cream fills in the pores of a
porous stone and cannot all be removed. The result of leaving
it there is that in time it may discolor or damage the stone.
Instead, use a mirror to shine sunlight
across the face of a stone, making the lettering stand out. You
should always prefer a
non-invasive method to interact with gravestones just as we do
with medical
tests on our own bodies.
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Is it possible
to remove graffiti left by vandals?
This is probably best done by professional
conservators. The type of paint and the method of application
requires skilled assessment to determine which products are
appropriate to remove graffiti without harming the stone. Time
is of the essence. The longer the graffiti remains on the stone
the more difficult it is to remove it successfully. See:
How to remove graffiti from historic stone
for more information.
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The stone has
broken at the base. The old base is either broken itself or we
can't get the stub out of the recess. How can we make a new
base?
How To Cast a New Base for a Stone
In the early 1930's WPA workers restored
many gravestone using the best-known material available, sand
cement.
Tablet stones were often placed directly
into bottomless forms filled with cement, or holes dug in the
earth were filled with cement and the stone thrust directly into
the "puddle". Many stones treated with this method have
subsequently broken at the point where the stone enters the
surface of the cement.
A recommended treatment for this situation
is to cast a base of concrete (pre-mixed works well) with a
recess for the stone of sufficient length, width, and depth to
permit using a high mortar mix to secure the stone in the base.
Step 1. The first step in this
process is measuring the stone to be reset (see fig.1) and then
preparing a form of sufficient dimensions based on the
measurements. Measure its height, width, and thickness.
Particular care must be taken when measuring the width and
thickness of that part of the stone that will be inserted into
the formed recess in the cast base. Irregularities such as
curvature, shoulders, and varying thickness must be taken into
consideration. Also, the end to be inserted into the recess in
the base must be at right angle (or nearly so) to the vertical
edge of the stone. A particularly "ragged" bottom may be
"trimmed" using a masonry blade in a circular saw. The safest
method is employing a monument dealer to do the "trimming".
(Fig. 1) Stone dimensions
Step 2. A "box" form should be
constructed that is 7 inches greater than the measured width and
7 inches thicker than the stone measurements. The height of the
"box" form should be at least 6 inches plus an additional ½ inch
for each 8-12 inches of the measured height of the stone. For
example, for a 42-48" height the box depth would be 6-1/2".
(Fig. 2) Box for casting a
new base
Step 3. Construct a block to form a
recess in the box. The width and length of the block forming
the recess should be at least 1 inch greater on both dimensions
than the stone, depth at least 3 inches plus 1/2 inch deeper for
each 8-12 inches of measured height of the stone above 36".
(Fig. 3) Side view of recess
block
Step 4. Thoroughly saturate the
interior surfaces of the box and the recess block with linseed
oil or similar material to insure the form will "release" the
casting when it is cured. Pour in the cement to the point where
the recess block makes an indentation. Secure the recess block
to the box form and continue filling the remaining space with
concrete tamping with a stick to compact the concrete. As soon
as the concrete surface becomes dull (about an hour) and a
trowel mark holds its shape, remove the recess block carefully.
Permit the casting to "cure" for a week, wetting it frequently
to assist the "curing” process (see Fig. 4)
(Fig. 4) Top view of recess
block in box form filled with concrete
(the dark-shaded area).
If the block has become too firmly embedded
in the concrete it can be extracted later using a masonry bit to
drill several holes up from the bottom until the drill reaches
the block; then drive the block out with a dowel. These holes
will be covered when mortar is introduced to set the stone.
Step 5. The cast base should be
allowed to "cure" for a week or so. Frequent wetting of the cast
will aid in the curing process.
Step 6. Set the new base into the
ground on a bed of pea gravel and sand for drainage. The top of
the base should be an inch or so below grade so that it does not
show since it could detract from the appearance of the stone.
Check that the cast is level lengthwise and crosswise.
Step 7. To set the stone in place, a
high lime mortar mix (1part #1 Portland cement, 4 parts hydrated
lime, 8 parts fine sand) should be prepared. First lay a 1/2
inch layer of mortar in the bottom of the recess, set the stone
in place, fill the perimeter with mortar to the top of the cast
base and slightly above shaping a "bead" to assist water run-off
(see Fig. 5)
(Fig. 5) Reset stone mortared
into the base and braced.
Step 8. Backfill and brace the stone
ensuring it to be plumb (vertical) and level. Remove brace
after a week or so.
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More
preservation information:
See "Tools and Materials for Gravestone
Cleaning Projects" and "Selected Brand Name Materials for
Cleaning Gravestones" in More Information,
FAQs.
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