Sealing Stone

[Don Dougan <dondougan@xxxxxxxx>]

Linda;

I pretty much agree with John Van Camp about the use of sealers - if what
you have been doing works and you are happy with the results then just
stick with it.

I work primarily in marble and Indiana limestone, though sometimes I use
alabaster for inlay work.  I don't always polish my stones -- sometimes
leaving them sanded to a matte finish.  I almost always want to use
something for indoor sculpture to seal the stone (wax is a sealer), so
oil and grease in the skin will not soil the stone surface over a period
of time with handling.  The following descriptions are for indoor
sculpture -- for outdoor sculpture I usually design the work to develop a
natural patina and/or make sure the client/buyer knows that a lot of
maintenance will be required on a regular basis to keep the stone in
'pristine' shape (regular applications of sealers/waxes and buffing).

Depending on the visual requirements of the piece I use different
sealers, and the following general methods are usually what I do.
Sometimes I play with the different combinations just to enhance an
effect.

For matte finishes I usually use colorless paste wax (TREWAX brand makes
one, and KIWI NEUTRAL SHOE POLISH also works, or if you are made of money
use ITALIAN CRAFTSMAN MARBLE POLISH) on white or light-colored stones so
they will not yellow.  The wax should be applied in a thin coat to cover
completely, but then buffed immediately (before the wax dries) with clean
soft white rags  (colored rags sometimes leave color on the stone).
These waxes can be used for dark colored stones too, but plain old
JOHNSON'S or MINWAX yellow paste waxes work just as well for dark colored
stones and you'll never notice the yellowing -- as long as you don't
apply the wax too heavily.

On very rough porous surfaces of Indiana limestone I use liquid
self-polishing acrylic floor finish (usually TREWAX brand, but BRUCE
makes one too) - brushed on and then immediately patted dry so it will
not polish itself and be shiny.  Note: the water in the sealer will
usually require several hours to dry out of the stone completely.

If I am polishing the stone to a high gloss I use either AKEMI brand or
TENAX brand liquid stone polishing fluid (available from stoneworking
tool supply or sculpture supply houses).  This solvent-based clear
water-thin sealer is expensive ($15 to $20 per liter) but it deepens the
color of the stone and minimizes any surface scratches by changing the
optical reflective properties of the stone's surface.  Again, like the
clear paste wax, apply sparingly but enough to cover, and then buff
immediately while the wax is still 'wet' to prevent streaking.  This type
of liquid polishing fluid can be used to 'touch-up' the finish very
nicely on alabaster [ . . . so easily scratched if you blink at it hard .
. . ?-)  ]

That said, once in a while I want the surface of the stone to be frosty
-- as when I sandblast a surface -- and sealer or wax would interfere
with the frostiness.  However the frosty surface also shows the slightest
oily touch.  What to Do . . . ?!?
When the frosty surface texture is important to the design, I simply
leave the stone raw from the sandblasting.  Then, after an exhibit where
it gets handled and is soiled with oily smudges from people's hands, on
the way back home I pull the pick-up truck into one of the Do-It-Yourself
car washes and hose the sculpture in the back clean with the pressure
washer  (soapy water first, then rinsed completely).
I have one two-color sculpture made with (frosted) Colorado Yule marble
and (polished) Champlain 'Radio' Black marble on which I use this
procedure.   It has had the pressure-washing procedure done to it (about
four or five times) after different exhibits with no ill effects
whatsoever.  Note: DO let it dry for at least 24 hours before packing it
away until the next show, and pressure washing is NOT RECOMMENDED for
alabaster or really soft stones -- unless you want to try carving sort-of
like Francesco Somaini . . .