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Plainsman Next Chapter

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Here is why new grinding equipment is needed

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These two pieces have been fired to cone 6, without glaze, I use this as a way of comparing changes in the character of the fired surface over time. These are made from a mix of A3 and 3B, the two main raw stoneware clays. The mix has been ground to 42 mesh (using a hammer mill). These materials vary in the amount of sand they contain and the amount of iron stone concretion particulates, so smoother and more speckle-free than this as a matter of normal variation. Plainsman has made sandy and speckled clays like this for so long that they seem normal. Yes, rustic bodies do have their appeal. However, the limits of the particle size reduction equipment and current quarry materials have resulted in importing American materials to satisfy customers who want smoother, whiter, more plastic and more vitreous bodies. Plainsman is now producing tens of thousands of boxes a year made from these imported materials! Transporting expensive clays at great distances begs the question of why not better leverage the clay resources that are right here. That, and associated independence, quality and lower production costs, are hopefully coming soon.

An All-Canadian Fine Ball Clay is in Sight!

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On the right is Plainsman A2 ball clay with 35% nepheline syenite added to vitrify it around cone 6 (these bars are fired at cone 2, 4, 5, 6 and 7 - top to bottom). The grinding equipment can process it to 42 mesh, as has been done since the 1970s. On the left is a Flintoft ball clay (cone 10R top and 10, 9, 8, etc - top to bottom). But this is the raw material, just slaked (not ground). It reaches zero porosity at cone 6 without a feldspar addition (because Mother Nature has added it for us). And the plasticity? This ball clay dry shrinks 9%, it is super plastic, much more than the A2/feldspar mix. While nearby deposits also contain refractory ball clays, this one is truly something special. It enables not just highly plastic vitreous stonewares but it fires white enough to be a potential ingredient in an All-Canadian plastic cone 6 porcelain. In an unexpected turn of events, there is an opportunity to get this clay in a way that is much easier than expected. Mixing this with PR3D has been tested, the best material in the Ravenscrag quarry - together the two can make killer clay bodies!

Another Saskatchewan Outrop:

We need to pay more attention

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This one is saying: "I am the whitest kaolin in Saskatchewan. And, I am so plastic that even though I am mixed with 50% sand, I can be modelled and formed with no problem. Just remove the sand and you will have a world-class kaolin that is Canadian". W. G. Worster, called these kaolinized sands, which can be found in south central part of the province, "splendid". This outcrop is in Halbrite, a small town southeast of Weyburn. There are lots of other deposits, especially in the Wood Mountain, Flintoft and Claybank area that are also much whiter than anything currently in Ravenscrag. But this one is king so far. Should Canadian companies keep importing from Georgia or should we develop our own Canadian kaolin?

Plainsman Ravenscrag Quarry in 2025:

It is Getting Complicated

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This has served the company for almost 50 years. The grinding plant, which has also served 50 years, has been able to process these clays to 20 and 42 mesh. While this quarry has been a key advantage for the company and coarsely ground bodies still sell well, the demand for smoother, more plastic and whiter bodies has seen a steady trend to the use of more and more imported 200 mesh powders (eg. clays, feldspar, silica) to make bodies. The star clay in the quarry is 3B, it is smooth and contains natural feldspar. Minings are typically done now just to get it. But because it is near the bottom (there are 6 layers plus overburden), others continue to bloat the inventory of unneeded materials (some of these piles are 30+ years old). On the next mining, the cost of stockpiling the overlying layers vs discarding them will have to be rationalized.

Most of these piles (especially the ball clay) could be sold on the open market if 200 mesh grinding was possible. The most serious problem is the amount of overburden that must be removed. Perhaps even more serious, since other clays are not needed, the 3B has to bear the entire cost of the mining. Now that better, more accessible and easier to mine clays further east have been found, the way forward is looking much better. In fact, it looks so promising (with testing of course) that it could be time to begin reclaiming this site.

This quarry has one saving grace: The bottom layer, which has been left in the ground the last two minings, 3D. It is the clean (low in contaminants) and, like 3B, contains natural feldspar. But it is not plastic, its usefulness depends on a better quality ball clay.

M340 and its glaze made from materials mined in Canada

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This is a cone 6 stoneware mug made using Plainsman M340. It is 100% raw clays mined from the Whitemud formation in the Ravenscrag area of southwestern Saskatchewan. The clay surface can be made white or black using our L3954B engobe. In this case the black version has been applied at the leather hard stage (by pour-in, pour-out on the inside and dipping on the outside). The GA6-B transparent amber base glaze is made using ~80% Canadian and Mexican-made ingredients.

Better clay deposits further east

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An update of the book "Clay Resources of Saskatchewan". The cover photo is titled "Kaolinized sand of the Whitemud Formation". The writers are lamenting the underutilization of this resource and almost pleading for industry to recognize its value! The cover shows the mining face at the historic Claybank brick plant. This clay is far whiter than what Painsman Clays mines at Ravenscrag, Sask (about 250km west of this). This site was mined from the 1800s to 1970s. Bricks were made in half a dozen large beehive kilns and, even though reduction-fired with gas, they burned far too white. The company increased reduction to the point that soot formed on the bricks to darken the color and turn them brown!

I am finally listening and rediscovering how much whiter and more pure clays are further east in Saskatchewan (compared to the current mining site in the west). This hill is kaolinized sand, that sand can be removed to produce a Canadian raw kaolin that could replace much the hundreds of thousands of tons that are currently imported each year from Georgia, USA.

A Highly Plastic White Burning Kaolinized Sand:

This proves we can have a Canadian kaolin

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This is kaolinized sand from Flintoft, Saskatchewan. It is among clays I am currently rediscovering. This is far more plastic and fires much whiter than the Ravenscrag quarry equivalent. Consider highlights of physical tests to characterize it (data shown lower left):
-Super refractory (thus theoretically pure). The SHAB test bars (lower right from cone 10R and 10 down to 6 oxidation) correspond to the SHAB test results in the chart. Even at cone 10, this has an amazing 19% porosity. With almost zero shrinkage.
-Plasticity: Excellent (notice the texture of the plastic material in the close-up photo on the upper left).
-The DFAC test disk upper right shows perfect drying performance and very low soluble salts.
-White burning: The top bar is reduction-fired yet barely darker than the one below it at the same temperature in oxidation (indicating low iron content).
-Centre-bottom: G1947U clear glaze on it fired at cone 10R.
-Easy-to-access in new and old quarry sites.
I compared this with about 10 other clays in the area, doing the same for all of them, preserving a treasure trove of data for clays I have been overlooking.

El Dorado of Pottery Clay Finally Found!

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It has been five years since getting and testing samples of an amazing porcelain-like, clean-burning, highly plastic middle-temperature stoneware raw material from south central Saskatchewan. It is far superior to anything seen till now. But, due to mix-ups, it appeared its location had been lost! But coming here to search again has turned up new information and I am quite certain this is the site (at Flintoft, Saskatchewan). Seeing and walking it has confirmed, contrary to the information I had, that the site is highly suitable for extraction (previous mine workings to the left are not shown). And, it is not the only site in the area. The Whitemud clays here are quite different from those in the Ravenscrag quarry, they are so good they obsolete almost everything there (except perhaps PR3D). On seeing the range and quality, I am beyond excited! There are a lot of ducks that have to be lined up to be able to actually extract from a site like this, but the location has a lot of advantages. The current economic realities will be a powerful motivator to developing Canadian clay sources.

Whiter Clays and Grinding Capacity:

Two problems solved in one place!

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This is at the Whitemud Resources metakaolin (MK) site midway between Scout Lake and Wood Mountain, Saskatchewan. They mine ore that is separated into kaolin (reject material is silica sand) then dehydroxylated into metakaolin; an SCM (Supplementary Cementing Material), MK itself is a natural aluminosilicate pozzolan. They have a giant plant (the dome is big enough to play soccer in) and are capable of processing incredible volumes. The mining face in their quarry appears to have the same layers as Ravenscrag. But, there are very fortunate differences:
-This deposit is near Flintoft, these clays will be much purer and whiter than those in the Ravenscrag quarry (pending testing, of course).
-Plainsman needs what is above the coal seam, they need what is below (their garbage is pottery gold).
-The layers appear to be the same as those in the existing quarry.
-Their grinding plant is capable of micron-sizes and is gigantic.
-Their by-product is silica sand!
-They are working on a mining plan for August extraction.
This is close to a "marriage made in heaven". It is certainly going in the direction of enabling improving product quality. And hopefully, soon an all-Canadian porcelain.

Mel Noble at Plainsman Clay's Ravenscrag, Saskatchewan quarry

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Six different sedimentary clays are extracted from this quarry. It was opened in the 1970s, the best location available at the time. These test bars were made by slaking select lumps from each layer (thus exhibiting their best performance). The left-most dried test bars show the layers (top to bottom). The A1 top layer is the most plastic and has the most iron contamination (it is used in the most speckled reduction firing bodies). A2, the second one down, is a ball clay (similar to commercial products, although darker burning), it is very refractory and the base for Plainsman Fireclay. A3, third from top, is a complete buff high-temperature stoneware (like H550), although sandy and over-mature at cone 10. 3B, third from bottom, is a smooth medium-temperature stoneware; it contains significant natural feldspar (although fired color and particulate contamination are the most variable). The second from the bottom, 3C. fires the whitest and is the most refractory (it is the base for H441G). The bottom one, 3D, the best product in the quarry. Although the least plastic and most silty, it is also very fine particled and the cleanest (consistently free of particulate impurities and sand), it pairs very well with a ball clay to make a cone 6 stoneware.

Three gifts have just fallen into our lap

Reflecting on the raw material path ahead

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Mother Nature has been good to potters in Ravenscrag, Saskatchewan. For 50 years Plainsman had reassured customers that "these rustic, textured, natural bodies are what Mother Nature gives us". They have made a science of helping customers take such bodies beyond their limits. However, change has happened. Expectations have increased. Many more users are hobbyists, they prefer not to deal with documentation yet want more plastic and smoother bodies with margin for error against failure. They use hundreds of bright colored commercial glazes that look better on bodies that are vitreous and whiter burning. Since materials in the current quarry are not suitable with their grinding equipment, the trend has thus been a relentless move toward making bodies made from imported materials.

However, gifts from three sources could reverse this:
-Mother Nature: Higher quality fireclays, kaolins and ball clays are available further east in the province.
-The current economic and trade climate: Higher-quality products made from low-cost domestic clays, less dependence on US imports.
-Existing mines in the "El Dorado" zone are available.
Couple these with mounting mining costs and a glut of unused stockpiles at the current quarry, it seems time to accept the gifts and move forward in exciting new ways.

Here is What Processing a Clay Can Do

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The clay is Plainsman 3B.
Left: Without processing, other than grinding to 42 mesh (currently the finest Plainsman can grind on a practical scale). When fired toward zero porosity it burns like this (at cone 6, 8, 9, 10 and 10R bottom to top). Of course, these are not big issues for non-vitreous rustic bodies fired at cone 6. The speckle and bloating are caused by impurity iron-bearing particles and others having an LOI (they decompose and produce gases that cause the bloats).
Right: The impurity particles make up a small percentage; they can be removed in the lab by sieving to produce a natural porcelain that fully vitrifies by cone 6 (the middle bar). Only about 5% of the material was removed to produce this amazing product (I call it MNP).
Imagine what could be done if this raw material could be mined further east, where clay quality is much better!

An upgrade to benefit "Mother Nature"

Replace the unbelievably inefficient driers

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For efficient powderization, grinding mills need dry clay. But Plainsman driers are unbelievably inefficient; basically, they are concrete saunas. Four tons of clay go in each of four; their 22 total burners go night and day for 10-11 months a year. And have done so for the past 50 years!

Thus, the equivalent of two full-blast burner-hours is needed to dry each box of clay from the 8-10% in the raw lump form down to 2-3% moisture. This is enough to fire the large gas kiln to bisque! A paved yard area for simple sun-drying would replace, reduce, or even replace these old driers (summer heat and dry weather are guaranteed here).

The ultimate: A rotary dryer. These are a standard for continuous processing in a wide range of bulk material processing industries (e.g. grains, seed, fertilizers, feeds, cereals, beans, wood chips, sawdust, chemicals, waste products, sand, gravel).

New incentive to develop Canadian clays:

Reduce the “clay miles”.

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The materials to make M340 travel 200km to get to the plant (from Ravenscrag, SK).
M370 is a different story. The kaolin (from Georgia) travels 3700km, the nepheline (from Ontario) travels 3100km, the silica (from Illinois) travels 2300km, the ball clay (from Tennessee) travels 2800km and the bentonite (from Wyoming) travels 1000km. Weighting each material distance by its percentage in the recipe calculates to 2900 clay-kilometres! Thus, all the boxes of M370 made in a year travel about 60,000,000 km, enough to go to the moon and back 50+ times! This realization brings renewed motivation to develop new clay deposits, ones that are white enough to make an M370-like body and which are only 400km away. Until then, you can cut the mileage now: Use an engobe on M340 and make it whiter than M370 (and darker than Coffee clay).

Rutile Blues - Almost every single stoneware potter uses them

These are made from Canadian materials and recipes

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There is a lot of magic, Canadian magic, in this picture. Pretty well every single potter working at mid-temperature needs rutile blue, gloss black, honey amber and transparent glazes (even multiple versions of each). And almost all need a base slip (or engobe). Here they are.

Upper left: GA6-C and GA6-B on light and dark burning bodies.
Upper right: GR6-M and GA6-C on M340 (with black engobe L3954B).
Lower left: GA6-C and GA6-B on M340 (with black engobe).
Lower right: GR6-M, G3914A, G2926BL on slow and fast cooled mugs.

Every glaze company makes multiple variations of each of these, especially rutile blues (or floating blues). Unfortunately, they often do not fit Plainsman Clays. But these do, in fact, they are adjustable (and better in other ways, as well as less expensive). Plainsman Clays mines and makes most of the raw materials, this is a great opportunity, hopefully soon realized.

Co-locate the QC Lab/Studio With Production:

So many good reasons to do this.

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In almost all cases, it is better to physically locate your quality control (QC) lab and studio close to or integrated with the clay body production facility. Here's why:
1. Faster Feedback Loop: Problems in production can be tested and addressed immediately. QC staff can pull samples directly from the line and respond in real time.
2. Improved Collaboration: Informal conversations and direct observation encourage faster recognition of issues and shared ownership of product quality. Production staff can observe lab tests and better understand why certain process controls matter.
3. Better Testing Relevance: Tests (throwing, casting, drying, glazing, firing) reflect the exact materials and conditions used in production, not outdated or transported samples. Factors surrounding run production are known.
4. Shared Culture of Quality: When the lab is physically distant, it can become an “ivory tower.” On-site, it becomes part of the process — not an external check, but a partner. Visibility of the lab reinforces its role in continuous improvement.
5. Lower Cost and Logistics: Less delay, double handling, and easier scheduling. Equipment and space can be shared.

I drink from these when I dream

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For many years, I have processed the clay for these myself, from lumps I get from the raw stockpiles behind the Plainsman plant. These are made from the PR3D raw clay mined near Ravenscrag, Sask. It is the bottom layer of six. It has the most potential for pottery because it is low in contaminants, fine-grained, light-burning and vitrifies well below cone 10. When I remove all particles coarser than 200 mesh (by slurry up and vibratory sieving) this becomes MNS (mother nature's stoneware) all by itself. Left: 200 mesh. Right 325 mesh. Centre: 150 mesh with added ball clay and feldspar to produce porcelain.

My coffee tastes better in these because they symbolize the potential of even the current quarry (as opposed to importing tens of thousands of bags of American clays each year). This is what I dream about. Processing the products past 42 mesh to get porcelain-like bodies. The finer particle size doesn't just unlock plasticity, but it eliminates problems that plague customers: glaze pinholing, fired specks, coarse particles and sand, even inconsistency and poor drying. Couple that with moving to a deposit further east and reduce soluble salts are reduced and clays get whiter. I even dream that this clay won’t get left in the ground, unmined, like what’s been done for the past three minings! Even that these glazes will be made. Is the future under our feet or in Tennessee and Georgia?

Recognize these universal oxidation glazes?

Almost every potter needs a Albany brown and rutile blue.

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These are made by Barbara Childs Pottery (I saw them on sale in a tourist shop in Alaska). To keep costs down, I first assumed they use dipping glazes they mix themselves. Potter's Choice PC-32 Albany Slip Brown and PC-20 Rutile Blue hobby glazes emulate these long time pottery glaze recipes. However, a reader noted that Barabara Childs uses Clay Art Center’s Stellar Rust and Floating Blue (with guest appearances by Blue Green). But Amaco and Clay Art don't just use the traditional recipes; they adapt and improve them. Consider the rutile blue. Neither is using the traditional G2826R floating blue recipe, there are new and better ways using recipes like GA6-C and GR6-M. Likewise, with the brown, they are not using the traditional G2415E Albany Brown recipe. Rather, they improve it (e.g. like we did with G3933G1). High on their list of improvements would have been a way to reduce or remove the lithium to cut costs. Maybe you are a hobbyist and don’t feel you need to DIY your costs down. But do your customers feel the same way? Not buying just ten small jars of hobby brushing glaze will pay for a mixer and much of the ingredients to make gallons of each of these as dipping glazes. It will also set you on the road to gradually improving the glazes you use. And even reducing your prices. What about buying premixed powders? Yes, that is much less expensive. But if you are mixing the glaze from one manufacturer with the clay body from another, crazing is an ever-present issue. Mixing your own enables an adjustment to fix the problem.

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