A.Tony Jucewicz
responds: When matching existing mortar, I
first try to decide whether a match can be achieved
using "standard" mixing ingredients. The pointing
mix I use consists of one part Portland cement and
three parts sand. Portland cement is available in
gray or white, and sand in my area is available in
white, yellow, or brown. When gray cement is used
in the pointing mix, the color of the sand has
little effect on the final color of the mortar.
When using white cement, you can control the color
with the sand used in the mix. White sand will
produce a white mortar, yellow sand a beige mortar,
and brown sand a light brown mortar with a reddish
tint.
In my area of Pennsylvania, I’ve had
the best success matching the mortar found in older
stonework by using white Portland cement and a
mixture of brown and yellow sand. Before I begin
pointing, I premix all the sand needed for the job.
The premixed sand can then be mixed 3 to 1 with the
cement.
If you can’t match the mortar using
readily available materials, you’ll have
to use solid-color dyes. These are packaged dry and
must be mixed in thoroughly when the sand and
cement are dry-mixed. You’ll need to make
numerous test batches and allow them to dry for
about two days before comparing them with the
existing mortar. However, after the dry materials
for each test batch are thoroughly mixed (and
before any water is added), you’ll have a
close indication of the final color.
Dry dyes tend to be very concentrated: A one- or
two-pound bag will tint a full 94-pound bag of
cement. If only one or two masons are pointing, a
full bag mix is too much mortar to mix at one time.
When making smaller batches, you’ll need
to carefully control the amounts used in the mix to
maintain a consistent color. It’s
important to finish your test samples the same way
you’ll be finishing the final work: A
brushed joint will have a different color than a
smooth troweled joint.
Tony Jucewicz is a stonemason in
Riegelsville,Pa.