|Monthly Tech-Tip |
A small clay mining and processing company located in Medicine Hat, Alberta, Canada. Plainsman makes dry and pugged clay bodies for potters, hobbyists and schools in the west. It is the only company in North America (among about 45) that mines its own clay to make most of these products. Plainsman also produces powdered clays that are used by other pottery clay manufacturers and special purpose clays that are used across North America in range of industries (e.g. manufacturing, smelting, health products, construction, refractories).
Plainsman’s existence is due to the convergence of several factors. It was started in a city having a ceramic manufacturing legacy since 1900, natural gas resources and a dry climate conducive to ceramic manufacture. At the time brick, tile, sanitaryware, stoneware, tableware, porcelain insulators and glass products were all being produced. This made available factory space and the mining and machinery expertise that was needed. And it had the stories of the capable people who started each of the companies. The city also had a tradition of the “craft of ceramics”. Thus, when Luke Lindoe, a combination artist, sculptor, potter, teacher, geologist, lab technician and dreamer came to the city in the 1960s magic happened when he discovered the quality of the sedimentary clay despots in the area. He was joined by John Porter, a British trained technician and potter with a flare for business. They set up shop and quickly developed a dealer network across Canada and the Pacific Northwest of the US.
Over the years Plainsman has maintained focus on supplying clay for pottery (resisting pressure to develop other markets that would distract from that). The vast majority of its products are sold wholesale through a dealer and store network. It has developed a solid product line and has large warehousing so that dealers can order at anytime and expect quick delivery. Plainsman also buys a wide range of materials, supplies, equipment and tools from around the world, both for resale and incorporation into its products. A potter can walk in the front door and buy almost anything he/she needs to begin product immediately. Recent years have seen much growth in pottery as a hobby and cottage industry, Plainsman now has as many as 10,000 customers using its products.
Plainsman Clays has also taken a leading role in providing online resources to assist its customers (and potters and manufacturers around the world) to have all the practical and technical guidance needed to make any type of product or to solve any problem.
Situated next to a beautiful park. On the left is the office, studio/lab, retail sales and order packing areas. On the right is the entrance to shipping area #1 (used for small-order shipping and miscellaneous receipts. Behind (not visible) is the factory and stockpile storage, driers and mixing areas. The domed beehive kiln on the left is the last of more than twenty. Plainsman is built on the site of the former Alberta Clay Products complex, a clay pipe manufacturer during the early and middle 1900s. The plant is literally sitting on top of broken-shard-rejects of decades of pipe and tile manufacturing. To the left of this picture is our main warehouse and shipping area #2 (for full semi-trailer load shipments and receipt of full loads of minerals and equipment).
The Plainsman Clays factory is right beside a baseball park. A beautiful place in the summer where children play and teams compete. But in the afternoon and evenings the deer move in. And mow the grass! The deer stay around all winter, in this residential area they are away from the coyotes and occasional mountain lion in the nearby river valleys.
This was built just after the turn of the 20th century and was one of about 25 at the Alberta Clay Products company. It was used to fire salt-glazed ceramic pipe, these were used for municipal sewer and water lines. A ceramic industry quickly grew in the city because it had good clay, natural gas, plenty of water, a dry climate, industrious people, a large river and it was on the Trans Canada highway and railway.
M2 is a dark red burning, middle temperature, moderate plasticity, low contaminant stoneware clay. It makes a great base for brown firing low and medium temperature clay bodies, less than 50% is needed for good body color. Plainsman Clays has been surface-mining it in Montana and importing it to Alberta since 1980.
Situated in the majestic Eastend river valley. The river has cut this valley over millions of years from the flat tableland 100 meters above, revealing all the layers of clay. These sediments were formed by the Western Interior Seaway. Today's river divides into two just west of here, leaving and strip of hills along the valley bottom. The hill being mined has minimal overburden to remove to uncover the layers of the “Whitemug Formation”. The reserves here are vast, the company has been mining just this one hill for 40 years, removing about 100,000 tons. Yet these layers stretch across the province and into Alberta. They are hidden from view except where valleys like this expose them.
These amazing hills near Big Muddy, Saskatchewan expose the sedimentary layers of the Whitemud formation (and others). The light-colored layer at the bottom is what Plainsman calls A3, it makes up about half of M340. But below ground is the 3B layer, the other half. The dark grey layers above the Whitemuds are what we call A2, a ball clay. Of course, top soil has accumulated on top of the clay to be able to grow plants. Although this is about 250km east of the Plainsman quarry at Eastend, Saskatchewan - the clay layers are remarkably similar. The clay resources in the area are truly astounding, not just in the quantity and quality but also in the magnificent landscape they define.
This is a "badlands" slope in the Frenchman river valley. The valley exposes the "Whitemud Formation" in many places (clearly visible here half way down on the left). Two surface mines of Plainsman Clays are nearby (over the top and down the other side), in a place where lower-lying rolling hills leave much less over-burden to remove. These materials were laid down as marine sediments during the Cretaceous period. The skeleton of the world's largest T-Rex, dubbed "Scotty", was found 50km east of here (in the layers just above the Whitemuds). Where are the layers of Scotties ancestors from the Jurassic period? Straight down until you hit the bed rock!
Plainsman extracts 6 different sedimentary clays from this quarry (Mel knows where the layers separate). The dried test bars on the right show them (top to bottom). The range of properties exhibited is astounding. The top-most layer is the most plastic and has the most iron concretion particles (used in our most speckled reduction bodies). The bottom one is the least plastic and most silty (the base for Ravenscrag Slip). The middle two are complete buff stonewares made by mother nature (e.g. M340 and H550). A2, the second one down, is a ball clay (similar to commercial products like OM#4, Bell). A2 is refractory and the base for Plainsman Fireclay. The second from the bottom fires the whitest and is the most refractory (it is the base for H441G).
This is the top layer. Battle clay is highly bentonitic, it is the "super hero of plasticity" in the quarry, it is unbelievably sticky. We have considered it "over-burden" in the past, but now will be looking for ways to employ Battle clay in our products and seeking special-purpose markets for it. Only 10% of this can turn a silt into a plastic throwing body! It is also high in fluxes (melts by cone 6). That means we can use it to improve the fired maturity of bodies, reducing the need for talc. Removal of this layer has exposed the top of the White-Mud Formation, the "A1" layer. A1 is employed in high fire bodies to impart brown color and fired speckle.
The machine has been reassembled after cleaning and is ready for startup. This pugmill is powerful and capable of injecting alot of energy into the material. Premixed powder and water are fed into the main mixing chamber by a screw conveyor at the far end. Dozens of blades on the rotating shaft inside cut and mix the material so that by the time it has reached half way in the main chamber all traces of powder are gone. At the end of the main chamber an auger delivers the materials to a venturi terminated by a shredder. This slices the material with dozens of tiny blades as it enters the vacuum chamber (yellow cover). This exposes as much surface as possible to the vacuum. Additional blades on the main shaft further mix the material and finally an auger compresses it and delivers it to the nose where a column is extruded for cutting to length and packaging.
The machine is being cleaned in preparation for a porcelain run. The machine has been stripped down completely and all the casings and augers and other parts have been washed and dried separately. These must be installed (in the main chamber, the vacuum chamber and in the nose). Clean-downs like this are an indicator of the quality delivered by the production crew.
These are two pallets (of three) that went on a semi-trailer load to a Plainsman Clays store in Edmonton this week. They are packed with hundreds of bags of powders used to mix glazes. More and more orders for raw ceramic materials are coming in all the time. Maybe you are using lots of bottled glazes but for a cover or a liner glaze it is better to mix your own. And cheaper! And there are lots of recipes and premixed powders here to do it. One of the big advantages is that when you dip ware into a properly mixed slurry it goes on perfectly even, does not run and dries on the bisque in seconds. No bottled glaze can do that.
This is our warehouse. It is really big! There are 20,000+ boxes in stock of almost every kind of clay we make (about fifty). Plus a hundred different ceramic material powders, many of which we buy in truckload quantities. We keep all kinds of equipment and supplies in stock also (in other storage areas), having a total value exceeding that of the clay. This means that when your dealer orders a truckload of clay, materials, supplies, tools and equipment from us, they get it fast.
This is a November 2020 shipment of wheels from Nidec-Shimpo of Japan. Although a large company, making drive mechanisms for many types of heavy equipment, they apply their technology to potter's wheels as a matter of pride in a country that reveres pottery in its culture. We have opened every box to reveal the serial number. A certified inspector will check each and affix another sticker to assure they meet CSA Code SPE-1000 for electrical safety. This approval enables the sale of the equipment to public institutions. And it assures you that the equipment meets CSA electrical standards and is safe and insurable for use at home. Wheels like these can last a lifetime. These are very difficult to find for sale as used. Where they are, it is not uncommon to see them sold for more than what was paid new. Within a week we sold 90 of these!
All of the equipment has been washed in preparation for a porcelain run. Original container bags are broken in the dust-hood unit on the right and augered and elevated into the rotating blender/mixer. It feeds a vibrating screen (not visible) that removes paper and other contaminants. For wet clay bodies the screen feeds hoppers on the other side of the wall, they in turn feed the pugmill. For dry bodies and glazes the powder goes to one of the hoppers and that feeds a bagging unit. This type of equipment can handle 1200 lb batches (doing one every five minutes for some products, longer for others).
Our main warehouse is actually a historic building in our city. It was part of the former Medicine Hat Potteries (1938-55) and then Hycroft China till 1989. We depend heavily on it to be able to maintain a large stock of bodies and materials. It needs a new roof, that is a big job on a building this size. The roof has multiple drain sites that feed to large pipe suspended inside, today was the day to test the new system.
These are raw clays behind the Plainsman Clays plant. The top one is a middle temperature stoneware. All it needs is a little bentonite (about 2-3%) to be a plastic, smooth, vitreous throwing body. If it was not mature at cone 6, that would be easy to fix by the addition of a little feldspar. Any fired-speck-producing impurities can be removed by using a propeller mixer to slurry it and then putting it through a screen (e.g. 60 mesh). After dewatering on a plaster table I am ready-to-go. And that bottom pile? That is the main ingredient in Ravenscrag Slip. All it needs is some feldspar and frit to be a base glaze at cone 6. It is non-plastic and easy to screen (although not really needed since it has few particulate impurities). Likely there are clays in your area you could use to make your own clay bodies and glazes also. The key is to characterize the material first so you know what type of body it would be best for and what to add to get it there.
Yes, this entire long line of pallets is only M340. It is not just reliable from a physical properties point of view but it has a reliable supply. M340 is our largest selling clay body. When customers go to a dealer to get some they will generally have it. If they order it from us we can ship it quickly because we have it in stock. And the stock turns over quickly so what the customer gets is freshly-made.
About Plainsman Clays