Mel Noble at Plainsman Clay's Ravenscrag, Saskatchewan quarry

Plainsman Clays 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).

Related Pictures

Core sampling at a Plainsman quarry during summer 2021

We are drilling test holes down through about 40 feet of overburden into the seven layers of clay to be mined. The rig assembles five-foot auger-sections, drilling down and pulling out two sections at-a-time. We examine the auger, identify the clays and record the results. At the middle of the auger-full shown you can see the division between the A2 ball clay and the A3 white stoneware, it was about 50 feet down. This hole was 80 feet, that spans tens of millions of years of sedimentation! This is the first time we have been able to sample the entire depth of the overburden, a highly plastic red burning low temperature clay, now we can assess whether it is a useful product.

Leaf fossil found in Plainsman 3D raw material

Casey Larson, our shipper and a pottery enthusiast, found this while breaking lumps on a stockpile. This is a very unusual find. The vast majority of fossils we find are preserved in iron stone concretions in our A1 raw clay, the top layer. Layers below that are highly plastic, as their lumps weather (many of which arrive the size of microwave ovens) they shrink and break down into smaller and smaller sizes. But our 3D material (the majority ingredient in Ravenscrag Slip and the lowest layer we mine) is less plastic so the lumps shrink much less as they dry. This keeps larger ones intact and has preserved this beautiful fossil imprint. This lump has been bisque fired to make the impression durable, thus the lighter color.

77 million-year-old mugs cataloged and exhibited

These mugs are made from clay mined from the Whitemud formation in southern Saskatchewan. Those layers date from the late cretaceous, the worlds largest T.Rex was found nearby. The errosive forces of nature during that period did a marvellous job of purifying and depositing this beautiful high temperature stoneware clay. It is basically complete right out of the ground, with just the right amount of feldspar and silica added to a ball clay and kaolin base. The glaze on these is G2571A bamboo, the engobe under it is L3954N black. They were fired at cone 10R. These are examples of mugs I make and catalog, each has its own pedigree web page that celebrates every detail about the materials and process used to make it (e.g. here is a pedigree page, it links to the mug's store URL). However please don't attempt to buy any, I am using the store as more of a gallery for now.

Links

URLs	https://www.plainsmanclays.com/index.php?menupath=18 About Plainsman Clays
URLs	https://www.plainsmanclays.com/ Plainsman Clays Website - This is authored by Digitalfire and is a reference website in its own right. It provides unparalleled documentation of clays and recipes and processes used by the potter customers.
Glossary	Secondary Clay Clays form by the weathering of rock deposits over long periods. Primary clays are found near the site of alteration. Secondary clays are transported by water and laid down in layers.
Glossary	Plainsman Clays
Materials	A1 Ball Clay It is very high in iron stone (pyrite) concretions and soluble iron salts, a heavily stained bentonitic ball clay.
Materials	A2 Ball Clay
Materials	A3 Stoneware Clay
Materials	B Clay
Materials	3C White Ball Clay
Materials	3D Clay
Projects	Plainsman 3D, Mother Nature's Porcelain/Stoneware
Projects	Mother Nature's Porcelain - Plainsman 3B This Saskatchewan clay contains natural feldspar, quartz and a variety of clay minerals, all blended by nature, to produce a porcelain, that although not white-burning, rivals or exceeds the strength achievable using industrial imported minerals
Articles	How to Find and Test Your Own Native Clays Some of the key tests needed to really understand what a clay is and what it can be used for can be done with inexpensive equipment and simple procedures. These practical tests can give you a better picture than a data sheet full of numbers.

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