ekrieger on sat 28 jan 06
I know there has been post about Black Jack clay but most of them =
several years old. At least that is all I've found.
I'm interested if anyone has had recent experience with that clay and =
what kind of results they are having with it. I'm particularly =
interested in using it for cone 10 reduction.
I noticed that the company only list one clay now and I know they used =
to have several clay bodies for sale. I also read some of the previous =
post that talked about a dark brown clay. The sample I got last week is =
more black. Has the clay body changed recently?
Any information is appreciated.
Eddie Krieger
Abilene, Tx
Craig Martell on sun 29 jan 06
Good Evening:
I enjoyed reading David's article on Black Jack Clay. I liked hearing
about a small clay company that used local clays and made good clay for
potters. If I lived in Texas I'd probably quit making porcelain and use
their clay. I should order a sample and give it a whirl on the 'ol Brent.
regards, Craig Martell Hopewell, Oregon
David Hendley on sun 29 jan 06
Hi Eddie, I have been using Blackjack Clay for 10 years and it has
been the same all that time.
For a while they made a "yellow ware" clay (now discontinued
I think), but other than that, only one claybody, called SS-2, has been
made and sold.
It is a deep dark brown - definitely not black, but dark brown.
Surprisingly, it fires to a light buff color.
I buy a large quantity at a time, so I have not bought any in almost
a year, but I talked to the owner last week, and nothing has changed.
The packaging says the clay is for "cone 6-10", but as longtime
Clayart readers know, it is really impossible for a claybody to fire
optimally at a range as wide as cone 6 to 10. At cone 6, it will be
far from vitrified - I would call it a cone 10 claybody. It is great in a
wood kiln, with nice flashing effects.
In case others hadn't noticed, Blackjack has been offering to send
a free bag of clay to anyone who would like to try it (you have
to pay the shipping, which, I know, is significant, but the clay is
free). See the ads in the current Ceramics Monthly or Clay Times
magazines.
I live about 50 miles from Blackjack, am an enthusiastic customer,
and wrote an article about it for CM in 2000. I've pasted the text
below, in case anyone is interested in learning more.
David Hendley
Old Farmhouse Pottery
david@farmpots.com
http://www.farmpots.com
Mining with the Potter in Mind
"My slogan says it all," John Morrison, the owner of Blackjack Clay Company,
says with a smile, "after you have thrown Blackjack clays, you never want to
throw any other, but out!"
This is a man who is confident about his product because it truly is
different from standard pottery clays offered for sale. "Our clays are mined
and processed with the potter in mind," says Morrison. "We control every
step in the process, from digging the clay in our own pits to putting the
de-aired extruded clay pugs in plastic bags." He continues, "The art and
studio pottery market is a very small percentage of the business of the
large clay companies. They mine and process their clays as heat-dried,
air-floated bagged clays for their large-scale consumers, and are not
concerned with the needs of potters. Any contaminates found naturally in the
clays, such as small rocks, lignite (a type of coal), and soluble salts are
all processed and bagged with the clay. Probably the most damaging part of
the processing is the drying of the clay, since heating robs the clay of its
natural plasticity. At Blackjack, we never grind or heat our clays. Our goal
is to optimize plasticity."
There's no denying the clay he is speaking of is a pleasure to work with.
It's
smooth and responsive, yet with enough body to be stretched without
collapsing. The claybodies are made by wet-blunging as a slurry and then
removing the extra water to produce plastic clay. Any experienced potter
will tell you that this is the best way to make clay. This kind of
processing allows each platelet of clay to be thoroughly wetted for maximum
plasticity, but it is seldom used because of the extra time and work
involved. Potters who are used to pugmill-mixed, heated and pulverized clay
are always pleasantly surprised the first time they try Blackjack Clay.
John Morrison started Blackjack Clay, Inc. in 1970, in the tiny East Texas
town of Murchison. No, he's not a gambler, he named the company after the
near-by, and even smaller, community where he grew up. The company is the
primary supplier of stoneware clay to all of the major industrial potteries
in East Texas. Although those big potteries represent the bulk of
Blackjack's
business, Morrison is also interested in giving studio potters, clay
artists, and students the opportunity of using a product specifically
designed for their needs. He will sell one 25-pound bag of clay if that's
all the customer needs.
All of the clays used in Blackjack's claybodies are mined within a
twenty-mile radius of the clay-processing facility. Some of the sites are on
privately owned land that is leased for clay rights, and some are on land
owned by the company. Morrison likes to point out that he treats his sites,
either leased or owned, with a deep sense of environmental commitment. "Our
rule number one is: do no harm!" says Morrison. "When removing earth from
an area, we always have a contingency plan in place to reclaim the land," he
says. "Typically, we work with the landowner to create a stock tank or a
lake. We know that environmentalism is a part of expert and responsible
manufacturing, a concept that many companies don't seem to understand."
In the world of clay mining, Blackjack Clay is a small operation. Forget
about photographs you may have seen of clay pits encompassing dozens of
acres, going down hundreds of feet. Most of Blackjack's clay pits are an
acre or less in size and go no deeper than 20 feet or so. This would be too
small to be considered commercially viable to a big clay company, but on the
more human scale of hand-thrown pottery, an acre of clay is a lot of
material. Typically, a particular clay is dug only a few weeks a year, and
is then stockpiled next to the pit to weather. The elements of wind, rain,
and sun help to wash away any residual soluble salts and to dry the clay so
it will more easily break into small chunks. When needed at the processing
plant, the clay is transported to covered bays next to the clay mixing
blungers.
Just as potters using dry bagged clays from the big clay companies combine
different types of clays to create a good claybody, at Blackjack they work
with several different clays, each with different characteristics. The clays
are named according to the area or name of the property owner where they are
mined.
"That's Jasper Clay. It's my EPK," says Morrison, pointing to a bay filled
with cream-colored clods of clay. "And this," he says, holding up a light
brown chunk of clay like a proud father with new baby, "is my ball clay. We
call it Vickery, and it is the most plastic clay you will ever work with."
Clays are chosen for various characteristics such as particle size, good
workability, and color. Blackjack's Production Manager, Karla Wagner, is a
ceramic engineer with extensive experience in claybody and glaze
formulation. She is kept busy with quality control testing for current
production, testing possible new clays, and designing new claybodies.
Currently, she is working on finding closer sources for claybody additives
such as fluxes, feldspar, and silica. It's not just a matter of looking for
closer and therefore less expensive materials, but part of the philosophy of
using local materials when possible. "If we can't get what we need locally,
we would at least like to make an 'all-Texas' product," says Morrison.
Once all the raw material bays at the Blackjack plant are filled with clay
transported from the clay pits, it takes about 24 hours to transform the
crude, hard chunks into pure, smooth, ready-to-use potter's clay. First, the
various clays are measured and dumped by front-end loader into a crusher
hopper mounted above the blunging tanks. A typical batch calls for about
five thousand pounds of clay. The high-torque, slow-moving mixer blades of
the crusher break the raw clay into fist-sized or smaller pieces and slowly
feed the batch into the water filled blunging tank. Bagged materials, such
as feldspar and 200-mesh silica, are added by hand. The batch is then
blunged in excess water using high-speed, low-shear agitation until it is a
smooth, creamy slurry. Next, the slurry is cleaned by a double screening
process. Impurities, such as rocks and roots, are caught in the first sieve,
and then the slurry is wet screened through a fine 60-mesh sieve to remove
any remaining impurities. From there, this smooth and homogenous slurry is
sent, via two-inch pipelines, to one of six filter presses. Using compressed
air, the filter press squeezes water from the slurry until it is about 20
per cent water, or plastic clay.
The water dripping down from the filter press looks clean enough to drink,
and, in fact, it is recycled back to the blunging tank for mixing with the
next batch. The filter press room is a good place to be on a hot Texas
afternoon: fans blowing across all that dripping water lower the temperature
by at least ten or fifteen degrees. After about three hours in the press at
120 pounds-per-square-inch of pressure, plastic clay, in the form of
"filter cakes" is removed from the press. Each pressing yields 68 one-inch
thick, thirty-inch diameter filter cakes, or about 2800 pounds of
throwing-consistency plastic clay. Much of the clay output is destined for
the big industrial potteries, so most of the filter cakes are stacked on
pallets, in heavy pallet-sized plastic bags to maintain the clay moisture,
ready for shipment. Clay for studio potters, sculptors, and students goes
through one more step, as it is sent to the nearby pugmill room, where it is
mixed, de-aired, extruded, and packaged in 25-pound blocks.
Jim Brooks on sun 29 jan 06
Eddie the clay still fires a rather light tan. i like the
clay.................
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