Plainsman Clays is built on the site of the former Alberta Clay Products Co. Ltd. The Plainsman plant is overlaid on the lower part of this 100-year-old photo. ACP was North America's second largest brick manufacturer. The plant and high temperature kilns, were all constructed using bricks and firebricks made in a temporary kiln on the same site (using clay mined nearby). No outside brick was purchased. The plant produced a wide range of brick but was most known for its production of vitrified salt-glazed pipe used in sewer and water lines across the west. During the period when this photo was taken the plant had 325 workers. In 1962 the main building burned to the ground! Shortly after, Plainsman Clays began operation in the small building beside the uppermost kiln. And moved to the current site in 1971.

Put the pots in, select a cone, press start. It is time to rethink that approach! Seriously. The Bartlett Genesis kiln controller is standard equipment on hobby and production electric kilns now. It is not meant to be run like a toaster! Good glazes are about much more than recipes, they are about firing schedules. None of the built-in "toaster schedules" have hold times on any segments, drop-and-hold sequences or controlled cools. Or even fire-to-cone accuracy. Yet such are a must for defect-free glazes, enhancing the effects of reactive glazes that must develop crystallization or variegation or firing accurately. It is easy to program: Tap the blue edit button to edit a program, tap a column of any segment to edit its value. Tap a segment number to delete or duplicate it. Google "bartlett genesis controller" for videos on creating and editing a schedule.

These are GA6-C Alberta Slip floating blue, AMACO Potter's Choice PC-20 Blue Rutile, GR6-M Ravenscrag floating blue. The clay is M390. The firing is cone 6, the schedule is C6DHSC (drop-and-hold, slow cool). The inside is GA6-B. The two on the left develop the blue color because of the slow-cool, the one on the right works on fast-cool because it contains cobalt (although it will fire somewhat more mottled). The centre one is a bottled commercial product, it was painted on in three coats. The result is quite compelling, this is a good place to start if you want the rutile-blue effect. Remember, these work best on dark-burning bodies.

This is the G3914A recipe on Plainsman M340 test tiles. They were fired at cone 04 using the PLC6DS schedule. We tested them in four different caustic liquids (using the GLLE test), there is no sign of leaching on any of them. This recipe contains only 4% black stain, that is enough to stain the base GA6-B glaze to a jet black. The surface has a unique iridescence not found in any other glossy black we have used.

Many people suffer high-percentage Gerstley Borate "bucket-of-jelly" raku recipes they find on line. Don't do this. There is a common Ferro frit that is perfect for this application, frit 3110 (Fusion frit F-75). All it takes is 15% kaolin (e.g. EPK) to produce and easy-to-use recipe that is guaranteed to craze. We have assigned it a code number of L4264, a raku base transparent recipe. We have also catalogued some common recipes that people use and outlined the issues they have: L4264A, L4264B, L4264C, L4264D. Do you need a white? It is a simple matter of adding 10% Zircopax to this.

These 1 mm-sized crystals were found precipitated in a couple of gallons of glaze containing 85% Ferro Frit 3195 (we have seen these with frit 3249 also). They are cubical, hard and insoluble. Why and how to do they form? Many frits are slightly soluble, the degree to which they are is related to the length of time the glaze is in storage, the temperature, the electrolytes and solubles in the water, interactions with other material particles present and the diligence of the manufacturer in mixing, correctly achieving the target chemistry and firing. The solutes interact or saturate to form insoluble species that crystallize and precipitate out as you see here. These crystals can be a wide range of shapes and sizes and come from leaded and unleaded frits. In industry this issue is not generally a problem because glazes are used soon after being made.

Fire-Red is an unusual material for several reasons. It has a high iron content yet is a fireclay (the iron percentage is so high that it fires black at cone 10R). It is also non-plastic. Most important, it is not ground to 200 mesh like industrial materials. These bodies demonstrate it well, left: 42.5% Fire-Red, 42.5% ball clay and 15% Custer feldspar, right: 60% Fire-Red, 30% ball clay and 10% feldspar. The ball clay adds plasticity. The feldspar gives control of the degree of vitrification (the left one has 1.3% porosity at cone 10R, the right one 1.5%). This recipe vitrifies so it does not exhibit the deep red color that Fire-Red would give if there was no feldspar. Look closely at the surface: It is covered by thousands of tiny iron-eruptions, they occurred as the iron pyrite particles liquified (because of the reduction atmosphere in the firing), these produce a metallic appearance. And, they will bleed through an over-glaze if present to give stunning speckled surfaces.

These were left overnight in vinegar and lemon juice. The top two are G3914A (GA6-B Alberta Slip base with 4% Mason 6600 black stain). Fired at cone 6. There is no sign of leaching (Drano and bleach likewise did not leach this). The bottom two are G2926B transparent with 10% manganese dioxide and 5% copper oxide added (also cone 6). G2926B is a proven base that does not show signs of leaching in any of the four liquids (containers lined with it were used for all tests). Not only was this not nearly as black, but the vinegar and lemon juice matted and blued it in an overnight soak (clearly visible on the top halves). Obviously, compared to raw metal oxides, a ceramic stain is a safer and much better way to produce a black functional surface.

These were fired at cone 04. All three clear glazes are on the same body. Left to right: Amaco LG10, G3879C and Crysanthos SG213. We mix the middle one ourselves, from a recipe that employs a high percentage of Fusion Frit F-524. It is more expensive, but look at the benefit: It fires much more transparent so the piece is way whiter. This frit has another benefit: It blends well with super low expansion Ferro Frit 3249 (and its equivalent Fusion Frit F-69). Notice the other two glazes are crazing. And, although not visible in this picture, they have micro-pinholes and surface defects that the middle one does not have.

These are the same clay, Plainsman M390. Both were brush-on glazed the same way. The one on the left was fired to cone 6 using the C6DHSC (drop-and-hold, slow-cool) schedule. The one on the right with the PLC6DS (drop-and-hold and free-fall) schedule. The label on the jar just says to fire to cone 6. But this is a rutile blue, and behaves like one.