This is kaolinized sand from Flintoft, Saskatchewan. It is among clays we are currently rediscovering. Unlike the one in our mine at Ravenscrag, this one has excellent plasticity when water is added (notice the texture of the plastic material in the close-up photo on the upper left). This dries quickly with low shrinkage (the DFAC test disk upper right shows perfect performance). Consider highlights of physical tests to characterize this material (data shown lower left):
-Super refractory (thus 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.
-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).
-Low soluble salts (upper right).
-Centre-bottom: G1947U clear glaze on it fired at cone 10R.
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.

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.

Reactive glazes (melt-mobile, crystallizing or heavily pigmented) are the least suitable for food surfaces because they have the potential to leach metals. Liner glazing ware is an excellent way to deal with this problem. Not only does this approach improve functionality but it can be aesthetically pleasing and practical in production.

This liner is GA6-B, a pottery glaze recipe we promote with confidence. Not only is it less likely to be leaching metals but also less likely to craze - this assures water tightness on non-vitreous bodies and eliminates any potential for bacteria growth in the cracks (especially if the body has porosity). Unfortunately, glazes that leach are also likely to stain and cutlery mark - these add more reasons why they are most often unsuitable for food surfaces.

The straightness of the dividing line is affected by both the application technique and the degree to which the two glazes bleed into each other and run. Read and watch our liner glazing step-by-step and liner glazing video for details on how to do this - it is practical for any potter or hobbyist (or even in production). And tap/click the picture above for other examples of this.

This jigger mold-making method features a hybrid plaster form of the outside profile attached to a 3D-printed clamping baseplate. Clamp-on rails enable easy setup and extraction for mold production. Here are the steps:
-Download the drawing, edit the bowl profile and size (and the template) and then 3D-print the parts (typically using PLA filament). Print two rails.
-3D-print threaded anchors and attach them to the base plate.
-Center and clamp the spacer ring onto the flat side of the base plate.
-Set the model mold on a level surface, pour plaster into it (right to the rim), place the base plate (anchors down) onto it (being sure it seats down into the spacer ring to assure centering). The plaster should overflow up the air holes in the plate. Weigh it down and leave to set.
-Remove the mold (using heat gun if needed), finish the surface of the plaster (with a metal rib or 3D-print one with curves to match the contour) and soap it in preparation for pouring a working mold.
-Clamp the rails down to the base plate (using paper clamps), place the mold on a perfectly level surface and fill with plaster.
-Fit the template to your jigger arm (more than one cycle of editing the upper section and adjusting hole placement will likely be needed, so don't print it solid right away).
You now have a working jigger mold for use on a Giffin grip. Repeat the last step as many times as needed.

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. Seeing and walking it has confirmed, contrary to the information we had, that the site is highly suitable for extraction. And, it is not the only site in the area, we are going to another that might be even better. 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.

This in on display at the visitor center of the Grasslands National Park in Val Marie, Saskatchewan. Perhaps ones like this formed part of the inspiration Luke Lindoe had when conceiving of the logo for the company he would form. To us, this area is "clay country", but to tourists it is a place to see the living prairie and also history like dinosaur fossils, the mass extinction boundary, hearth sites, tipi rings, bison drive lanes, and cellar depressions.

Many people suffer high-percentage Gerstley Borate "bucket-of-jelly" raku recipes they find online. Most of these are just transparent base recipes to which colorants are added. After years they found ways to tolerate this strange bedfellow. Now, a more normal material, Gillespie Borate, seems odd and is causing issues in the alternate reality "Ghastly Borate ecosystem". There is a better way. A frit is perfect for this application, Ferro Frit 3110 (or Fusion frit F-75). All it needs is 15% kaolin (e.g. EPK) to produce and easy-to-use recipe that is guaranteed to craze. The degree to which it crazes can be adjusted by trading off some of it for Ferro Frit 3249. 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.

This is not as good as using a cup-head, but it has advantages for potters and hobbyists. These include easier mold making, only the top side needs to follow a precise contour, the bottom is just flat. And a wide range of sizes can be accommodated. It is also more convenient because the wheel head of the potters wheel does not need to be removed. And, of course, it is less expensive.

Pretty well all common traditional ceramic base glazes are made from less than a dozen elements (plus oxygen). Go to the full picture of this table and click or tap each of the oxides to learn more (on its page at digitalfire.com). When materials melt, they decompose, sourcing these elements in oxide form. The kiln builds the glaze from them, it does not care what material sources what oxide (assuming, of course, that all materials do melt or dissolve completely into the melt to release those oxides). Each of these oxides contributes specific properties to the glass. So, you can look at a formula and make a good prediction of the properties of the fired glaze. And know what specific oxide to increase or decrease to move a property in a given direction (e.g. melting behavior, hardness, durability, thermal expansion, color, gloss, crystallization). And know about how they interact (affecting each other). This is powerful. A lot of ceramic materials are available, hundreds - that is complicated when individual materials source multiple oxides. Viewing a glaze as a simple unity formula of ceramic oxides is just simpler.

This is part of a test hybrid case mold for a Medalta Potteries ball pitcher. The bottom plate is 3D printed and the top form is solid plaster. Recessed holes in the back of the plate enable securely inserting screws into threaded anchors embedded into the back of the plaster form. The upper plaster surface has artifacts (stair-casing remnants) from the 3D printed shell used to cast it. While these could be sanded out, we find that a flexible metal rib works much better. Even better than that is this custom 3D printed rib that I made, the edges are sharp and precise. I designed it with contours to match the belly, neck and rim of this piece. Using this, it takes minutes to smooth out the surface.