A Highly Plastic White Burning Kaolinized Sand:

This proves we can have a Canadian kaolin

This is kaolinized sand from Flintoft, Saskatchewan. It is among clays we are currently rediscovering. This is far more plastic and fires much whiter than our 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 we have been overlooking.

Related Pictures

Will soil testing help you assess a wild clay for pottery?

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No, soil testing is not helpful. Soils normally contain clay but it is so diluted with sand, rocks, silt and organics that overall plasticity is just a dot on a graph - not even close to what modelling or throwing clays exhibit. Pottery clays easily hold a shape and can be adjusted to a new shape without splitting. They dry slowly with substantial shrinkage. Highly plastic clays need more water to achieve working consistency, silty non-plastic ones need less (typical pottery clays need 18-23%). The reports shown here are typical for soils. But almost nothing here would look familiar to a potter.

-The Shrinkage Limit (SL) is the water content where further loss of moisture will not result in any more volume reduction.
-The Plastic Limit (PL) is minimum water content at which a soil is considered to behave in a ‘plastic’ manner, i.e. is capable of being moulded.
-The Liquid Limit (LL) is the maximum water content a silt or clay can have before becoming a liquid, i.e. turning into mud.
-The Plasticity Index (PI) is the range of moisture contents where the silt or clay remains plastic (PI = LL – PL).

Potters don't care about the amount of water needed, they care about how plastic the clay is once enough water has been added to get the right stiffness.

We Have Been Overlooking Better Clay Deposits

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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!

We are finally listening and rediscovering how much whiter and more pure clays are further east in Saskatchewan (compared to our 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.

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 we have 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 we 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 our Ravenscrag quarry. 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.

Videos

Links

URLs

https://claybankbrick.ca/
Claybank Brick Plant National Historic Site
A refractory brick manufacturer, cradled in the Dirt Hills of Southern Saskatchewan, for 75 years (from 1914-1989).

URLs

https://insight-live.com/index.php
Insight-Live.com cloud-based ceramic lab notebook and education platform
Ceramic-industry-specific LIMS Lab information management and education system from Digitalfire. This is the software and information to study, understand, adjust and formulate glazes and clay bodies. Replace excel and word documents with a searchable cloud-hosted database accessible from any web browser. View anything side-by-side. Track unlimited specimens and manage large numbers of simultaneous projects. No need to request a quote, just sign up.

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