Step 1
Making the clay slabs is the first
step in all slab-built pottery construction. This is an important foundation;
mistakes made in the creation of slabs may destroy the piece in later stages of
construction.
Step 2
Clay
"Grain"
Damp clay is made up of fine
platelets which ride within a thin cushion of water. When a slab is rolled out,
the pressure thins out the clay and also moves the platelets so that they are
aligned with the direction of the force. In essence, the clay takes on a grain,
much like the grain in a piece of wood. Unless modified, the platelets will
remain aligned in that grain throughout drying and firing.
This is where problems can develop.
Grain in a slab will affect the clay's shrinkage. The slab will shrink more
along the width, across the grain, than it will along its length, or with the
grain. If pieces are assembled so that the grains aren't aligned in the same
direction, the pot can literally pull itself apart during drying and firing.
Step 3
Getting
Rid of the Grain
Avoiding the creation of a grain
while making slabs is actually easy and quite straight forward. Simply take the
time to rotate the clay after each rolling. It is also helpful to flip a slab
over and roll it on both sides, rather than just one.
In order to flip a large slab, you
will need two pieces of canvas, larger than the slab will be. Begin by rolling
the slab on one piece of canvas. After the initial rolling, cover the slab with
the second piece of canvas. Spreading out your hands as much as possible to
support the clay, flip the canvas-clay-canvas sandwich over. Remove the top
layer of canvas (that used to be the bottom) and continue rolling.
You can use wooden slats, such as
these pieces of lathing, to ensure a slab is rolled out to a uniform and
specific thickness.
Step 4
Rolling
Pins
One of the easiest methods of making
slabs is to use a rolling pin. Large, heavy ones with ball bearings at each end
tend to work the best.
If you want to be certain that a
slab is uniform in thickness, you can use two slats of wood on either side of
the slab as depth guides. Just be sure to rotate the slab as you roll, rather
like rolling out pie dough.
You can roll a very thin slab of
clay by placing the clay between two sheets of plastic wrap. These thin slabs are
useful for appliqué work. . Beth E Peterson
Making
Really Thin Slabs
What if you need a very thin slab,
such as for clay appliqué or to laminate onto a pot? The slab needs to be very
thin, which can mean difficult to roll out successfully using normal methods.
Use plastic wrap instead of canvas.
Flatten the clay between your palms, then lay it between two sheets of plastic
wrap. Roll with a rolling pin, being careful that no wrinkles develop in the
plastic.
Rotate and roll out again, repeating
this sequence until the clay is as thin as you desire. Carefully pull the
uppermost piece of wrap straight back and away from the clay.
After firmly applying the thin slab
to the other clay surface, pull the second piece of wrap straight back and
away. The clay slab should stick to the other clay surface.
Step 5
Make
a Super-Strong Slab
You may want to work with enormous
slabs, very thin slabs, or you may want to use them in ways that damp clay
generally isn't strong enough for. If this is the case, consider adding chopped
nylon to your clay body.
To do this, add a couple of handfuls
of chopped nylon per hundred pounds dry weight to the clay as you mix it.
Sprinkle the nylon in while the dry clay is combining in the clay mixer, before
adding the water.
You may also be able to special
order a custom mixed batch of clay; check with your favorite supplier.
Step 6
Slab
Rollers
Slab rollers are wonderful pieces of
equipment if you are using large quantities of slabs in your work. They are
fairly expensive, though, and do take up a lot of studio space. You may find
that a large rolling pin will do the job for you just as or nearly as well.
Again, when using a slab roller care
must be taken to avoid creating a grain in the clay. If the slab is too long to
fit width-wise in the roller when rotated, roll across the width of the slab
with a rolling pin using very positive, even aggressive, strokes.
