Normal Hours of Operation
Next closure for a stat holiday is on Remembrance Day, Nov 11, 2020
Covid-19 Status: Click here to find out more
Western Canada's largest distributor of pottery materials and supplies. Clays, raw materials, tools, wheels, kilns, slabrollers, books & much more.
Our continuing goal is to supply artists, potters and crafts people with great quality products, knowledge and customer service. Our staff is familiar with all the items we stock and can help you through the selection and ordering process. We will also see that your order is shipped according to your directions, or put together for pick up at our retail store in Surrey, BC.
Technical Tips Blog
An incredible M390-compatible cone 6 red-burning casting body
This mug was thrown. But the handle was cast from L4005D, the recommended recipe for an M390-compatible casting body. This is not a product you can buy, you have to mix it yourself, but we have plenty of instructions and pictures. The fired maturity of the two (fired shrinkage and porosity) matches very well. The casting process is superior for certain shapes and ware types. And now, with 3D printing, it is much easier to make many kinds of casting molds. This handle mold is made by pouring plaster into a 3D printed form. These are strong, the handle on this glazeless mug endured a couple of good taps with a hammer and stayed solid. With glaze, the strength would be much better. The body fires a little browner in color than M390. It would be redder if we included more iron oxide in the recipe, but that would gel the slurry and make it harder to work with. As a red-burning body, this one has better casting properties than any other we have used.
Thursday 29th October 2020
Plainsman Warehouse 1 getting a new roof
Our main warehouse is actually a historic building in our city. It was part of the former Medicine Hat Potteries (1938-55) and then Hycroft China till 1989. We depend heavily on it to be able to maintain a large stock of bodies and materials. It needs a new roof, that is a big job on a building this size. The roof has multiple drain sites that feed to large pipe suspended inside, today was the day to test the new system.
Context: Plainsman Clays
Thursday 29th October 2020
This on only 2/3 of the M340 we have in stock!
Yes, this entire long line of pallets is only M340. It is not just reliable from a physical properties point of view but it has a reliable supply. M340 is our largest selling clay body. When customers go to a dealer to get some they will generally have it. If they order it from us we can ship it quickly because we have it in stock. And the stock turns over quickly so what the customer gets is freshly-made.
Context: Plainsman Clays
Tuesday 20th October 2020
Knowing about recipe limits would save you the work of testing this glaze
This is an example of a recipe being trafficked online that raises red flags just looking at it. The first red flag: There is no silica! That means this is a low fire glaze masquerading as middle temperature, so it is going to run during firing (run a lot). It will also mean poor durability. There is a ton of feldspar, that means a high level of sodium. Without low-expansion MgO to counterbalance it's high thermal expansion the glaze is likely going to craze badly. The mechanism of the crystallization is titanium over-supply, this has triple the maximum I would ever put in a glaze. The crystallization happens during cooling in the kiln (producing the visual effect being sought). But the the surface produced will cutlery mark and stain, probably very badly. Given the unbalanced chemistry this has, any colorant added will likely be leachable! I tested it and all my fears were realized. My slow-cool firing made the surface so dry it was very unpleasant to touch. Maybe this needs fast cooling. But who knows, there are no notes. This does not appear to belong on any functional ware, inside or outside. Someone noted that people use this to produce layering effects (see links). That begs documentation on how that wold work. Without gum would it lift and crawl as layers are added over it. Would you have to overlay every square inch? Would it still craze? All the how-to information needed to make it work are more important that the recipe itself.
Thursday 15th October 2020
G1916Q transparent on terra cotta body at cone 06, 05, 03
The body is Plainsman L215. We used the 04DSDH firing schedule. The glaze is inexpensive to make so we have a 2 gallon bucket. It has good dipping much like a stoneware glaze so it is easy to apply quickly and evenly. For most terra cottas, body strength increases dramatically by cone 03. However the most transparent and glassy glaze surface happens at cone 06. Terra cotta bodies need to be bisque fired fairly low (e.g. cone 06) to have enough porosity to work well with dipping glazes. After cone 06 they generate increasing amounts of gases (as various particle species decompose within), for this reason the glazes can have more micro-bubble clouding or tiny dimples in the surface. This glaze has 2% iron oxide added as a fining agent to remove the bubbles. That iron also reddens the color and variegates the surface somewhat. Even though the surface character at cone 03 is not a smooth, it has a natural charm, and the color is very rich. And that piece has stoneware durability and strength.
Thursday 15th October 2020
Add 2% iron oxide to a transparent glossy low temperature glaze to get better color, less clouding
Both pieces are the same clay body, Plansman L215. Both are fired to cone 03. Both are glazed using G1916Q recipe. The glaze on the piece on the left has 2% added iron oxide (and sieved to 80 mesh). Each grain of iron (which is refractory in this situation) acts to congregate the micro-bubbles so they can move through the glaze layer. Notice also how much richer the color is on that piece. The piece on the right does not have added iron oxide. It is not as red and not as transparent. Both of these mugs, by the way, are glazed on the bottom and were fired on stilts.
Wednesday 7th October 2020
G1916Q on L215, L212, L210, L213, Buffstone at cone 03
The G1916Q recipe uses common Ferro frits and fits most low fire bodies (except this with high talc). It is easier to tune its recipe to adjust thermal expansion adjustable than others we have published in the past. And it melts well down to cone 06. And we have a strategy to reduce clouding and micro-bubbling. These five test tiles were fired using the 04DSDH schedule (drop-and-hold) firing schedule. Results are flawless. All exited from the kiln without crazing. The L215, L213, L210 and L212 samples subsequently survived a 300F/Icewater test without crazing, but the Buffstone did not (it needs a higher thermal expansion glaze adjustment). The L213 would not likely survive a cold-to-hot test without shivering (it needs a lower thermal expansion adjustment).
Wednesday 7th October 2020
The first of 15 "Fool-Proof Recipes" wrecked my kiln shelf!
This is recommended in the booklet "15 Tried and True Cone 6 Glaze Recipes". This melt flow tester compares it with a typical cone 6 glossy, G2926B. This recipe is 90% Frit 3110 and 10% kaolin and their booklet recommends adding stains to it. But anyone knowing a little about this frit knows it would run off this flow tester even before bisque temperatures. It is crazy to recommend this. Even as a crackle. For cone 6 it needs to be diluted much more, not just with kaolin but also silica. I knew this would run but I underestimated its melt fluidity. I put a large tile below the tester to catch overrun, yet the melt ran off that and a big three-cm-wide blob melted through the kiln wash and so far into my zircon shelf I cannot chip it off! I cannot imagine how many people have tried this on vertical surfaces and had the same thing happen. The lesson: Use common sense when looking at recipes, then you don't even need waste time testing them. Even if their authors did not!
Wednesday 30th September 2020
Saint Rose Red being delivered. Look what it does at cone 10R!
We get this clay from St. Rose, Manitoba. Four tandem loads arrived this week. Just seeing the pile inspires me to make more pieces! It is a red fireclay and it is highly unusual. St. Rose Red has issues. They at first seem to be problems, but in combination they give it magic powers! It fires with very heavy iron speckling. The iron pigmentation is so high that it burns almost black at cone 10R. It has low plasticity. It shivers glazes: The vase on this picture lasted an hour after kiln exit, it spontaneously fractured because of the outward pressure from the under-compression glaze on the inside. But, by combining St. Rose Red with our more vitreous clays, which are highly plastic, we can make H440 and H443. But guess what happens when feldspar is added? A mix of 45 St. Rose, 40 Ball clay and 15 feldspar produces a rustic metallic surface (like the cup shown). Such a body cannot be made from a low fire red clay (like RedArt), it would just warp and collapse in the kiln. It is the refractory character, heavy pigmentation, iron speckling and low plasticity of St. Rose that make metallic ware possible.
Wednesday 16th September 2020
Polar Ice Porcelain with Body Stains - by Robert Barritz
Robert has done really valuable work in this research, what an amazing range of color! I am so grateful he shared this with the rest of us. Surfaces are unpolished and unglazed. All are fired to cone 6. Browns are missing, they can be made using iron oxide. For blacks, Mason 6600 is also effective. The blues require lower percentages than shown here, as low as 2% can be effective. Likewise with others, there is an optimal amount for each stain, beyond that, with increases in percentage the color intensity increase will drop significantly. There is another reason to keep stain percentages to a minimum: To reduce the impact on body maturity (and firing shrinkage). Blues, for example, can significantly heighten the degree of vitrification, even melting the porcelain. If you plan to marble different colors, keeping stain percentage as low as possible is even more important, unless you can do fired shrinkage compatibility testing, for example, the EBCT test. Need to develop your own white porcelain? See the link below.
Context: Mason 6027 Stain, Stain 6200, Mason 6255 Stain, Mason 6266 Stain, Frit VO 6200, Frit VO 6255, Mason 6363 Stain, Mason 6304 Violet Chrome Tin, Mason 6308 Stain, Mason 6306 Stain, Mason 6368 Copen Blue Stain, Stain 6388, Stain 6234, Stain 6219, Mason 6021 Red Stain, Spectrum 2276 Yellow Stain, Mason 6464 Yellow Stain, Mason 6485 Yellow Stain, Mason 6537 Grey Stain, Mason 6386 Blue Stain, Mason 6600 Black Stain, Stain 6121, Stain 6201, Stained Plainsman Polar Ice Porcelain - With Polishing (no glaze), Develop and maintain your own cone 6 porcelain recipe, Ceramic Stain
Monday 14th September 2020