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use
a dust collector and if possible, work outside. I use a Makita 410
dust collector, with its intake nozzle mounted near the tool rest.
This clears the air and helps keep the dust out of the headstock
bearings. In addition to breathing problems, the dust can dry out
your skin severely, so I wear latex gloves. Of course, wear a face
shield: These are rocks, not wood chips, that will be flying off
the lathe. I recommend steel-toe shoes, because the rocks are quite
a bit heavier than wood, and if you turn enough of them, you will
inevitably drop one off the lathe. The last time this happened to
me, the 105-LB. piece hit the floor and rolled through the wall.
Attaching alabaster
to the lathe - I usually start with a pin chuck from the rim
side, then proceed as shown in the photos on the facing page. The
only unusual gadget I use is a device to center and clamp the preturned
wood base to the piece. It is a simple stub with the proper Morse
taper for the tailstock on one end and threads for a faceplate on
the other end. With the bowl on the headstock and the base on the
faceplate, I screw the base/faceplate assembly onto the stub, insert
the stub into the tailstock, then wind the tailstock out until the
base and bowl connect. This avoids turning a mortise and tenon to
center the bowl on the base.
You can also adapt other
chucking systems to alabaster. You can grind a flat on what will
be the base of the piece with a belt sander, glue on a preturned
wood base, glue or, for small pieces, double-tape a waste block
to this base and screw a faceplate to the waste block. Or, you can
grind a flat on the rim side, tape it to a faceplate, turn the outside,
then glue on a base and waste block as before. Use whichever method
seems most comfortable to you.
Turning techniques
- You must rely on a fairly gentle touch as you turn, because alabaster
isn't flexible. The rotational energy of the lathe must be absorbed
by the tool, the tool rest and your hands, or by the scraping away
of the stone's surface. Too much pressure or a slip with the scraper
either stops the lathe, knocks the piece off the faceplate or breaks
the stone.
You will likely find
two additional crystals in alabaster: quartz and selenite. Quartz
crystals are very hard and may be as large as a pencil eraser or
as small as a grain of sand. You will feel them and hear them; they
will take the edge right off your tool, sometimes making sparks
as they do so. If you run into quartz, stop and dig it out. My "quartz
digger" is simply a concrete nail with a piece of wood for
a handle. Selenite is another crystalline form of gypsum. It usually
is found on the outside of the rocks and looks similar to mica.
You can cut selenite, and if it runs deep in to the rock, it can
yield spectacular results. But, selenite crystals usually separate
from the rest of the piece, so keep filling with Hot Stuff as you
turn, as this will sometimes keep the crystals in place.
If you decide to permanently
attach a wood base or rim to the alabaster, the Hot Stuff glue makes
a good permanent bond. Whenever one of my joints has failed there
has always been a layer of alabaster left attached to the wood,
indicating the stone, not the glue, as the weak link. Just remember:
The wood will move as its moisture content changes; the stone will
not. With wood pieces as small as the rims on these bowls, wood
movement doesn't seem a problem; with the larger pieces, it can
be. After the piece is turned, finish all surfaces of the base with
a moisture-sealing finish.
Finishing alabaster
- I first sand the surface with 36 grit for rougher shaping, working
up through 15-micron sandpaper (available from The Luthier's Mercantile,
Box 774 412 Moore Lane, Healdsburg, Calif. 95488; 707-433-1823)
for that final glow. I use all the sandpaper dry. My favorite finish
is paste wax, but you might prefer lacquer or the traditional oil
finishes commonly applied to wood turnings.
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Finding
alabaster
I get most of my stone
from Colorado Alabaster Supply, 1507 N. College, Ft. Collins Colo.
80524; (303) 221-0723. Stan Jones, the owner, says that the company
deals mostly be the ton, and small pieces suitable for turning are,
in effect, waste that may or may not be available at any given time.
You may have to wait six weeks to two months for delivery of a small
order. Typical cost is as low as 30¢ to 35¢ per pound,
with a nominal handling charge.
I suggest you start with
a 20-lb. to 30-lb. block, which in my experience, would be large
enough for a 6-in. by 2-in. bowl. Drill cores of 2 in. to 3 1/2
in. in diameter are sometimes available, too. Here again, if you
want 500 lbs. of cores, Jones will be happy to core out as many
rocks as necessary; if you want 10 lbs. and he is out, the order
might take a while.
A speedier yet more expensive
route is to order from a specialty supplier. Sculpture House (30
E.30th St. New york N.Y. 10016; 212-679-7474 has alabaster (mostly
imported Italian) for immediate shipment and will help you figure
out what to order ever the phone. Cost is $1.50 per pound, and the
minimum order is $50.
You might be able to
obtain the rock from local sculptors or sculpture-supply houses
as well: Alabaster is a very popular carving stone. Here in the
West, you can often find alabaster at rock shops along the highway.
If they don't have it, they probably know who does.
Another approach is to
become a prospector. which gets you the best prices of all, usually
free. Look for places on the map with names like Alabaster, Gypsum
or Plasterville. Gypsum, the main component of Sheetrock, is fairly
common, and where there is gypsum there will be alabaster. By asking
around, you can usually get permission to dig it. The question is
whether or not it will be solid enough and large enough to be useful.
Here's how to test: You want a piece that gives off a good ring
when struck. Pick the piece up and give it a sharp tap. (My favorite
tapper is a wooden-handle rigging axe, which is a framing hammer
that combines a typical hammerhead with a hatchet face instead of
a claw.) A solid piece will have a clear clink or a ring. If you
get the sound of an indistinct "thud," look for fractures
and break off anything that looks loose, or try holding the piece
differently, then tap again. this is easy for a 20-lb. rock. With
a 150-lb. rock, however, it is more of a problem; still you can
usually balance it on a corner and get a ring. With a 500-lb. rock,
good luck! -M.K.
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One final caution about
finishes: Your bowls must be purely decorative or at least reserved
for the storage of dry goods, because alabaster dissolves in water.
How quickly? Well, a few drops of water on a waxed alabaster surface
probably won't make marks, but I once filled a bowl with water and
the liquid noticeably etched the surface in half an hour. Obviously,
if there is a fracture in the piece where water can seep through,
things will only get worse. To avoid this kind of damage, I sometimes
lacquer the inside surface, especially on enclosed shapes. I don't
especially like the look or feel of the lacquer, but it is hard
to see inside these enclosed vessels anyway. I also think that with
enclosed shapes it is more likely that someone down the line will
l put water in them. In those cases, lacquering should work fine,
unless a possible natural fracture in the stone eventually causes
the lacquer to check.
One of the best rules
when beginning to work with alabaster is that if at first you don't
succeed, keep trying. As I mentioned earlier, about 20% of my starts
are failures, but in the beginning, they were more like 40%. Half
of these are due to excessive concentrations of quartz or structural
problems with the stone, and half are just my mistakes. Have fun:
After all, that's the ultimate point of it all.
Max Krimmel is a
guitarmaker, illustrator and turner. He lives in Boulder, Colo.
All photos are by the author.
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