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Important Notice

Plainsman Clays Ltd. will be closed to public access starting Thursday March 19. We will keep the doors closed (no exceptions), but continue to take and fill orders via phone (credit card only accepted) and e-mail. Pick up orders will be placed on at the front of the building, however we will be unable to assist in any loading. These measures allow us to limit contact with customers and minimize any risk with regards to the COVID-19 virus.

We can be reached by phone at 403-527-8535, fax 403-527-7508 and via email at plainsman@telus.net.

Thank you for your understanding during this difficult time.

Mother Nature's Porcelain - From a Cretaceous Dust Storm!

Plainsman Clays did 6 weeks of mining in June-July 2018 in Ravenscrag, Saskatchewan. We extracted marine sediment layers of the late Cretaceous period. The center portion of the B layer is so fine that it must have wind-transported (impossibly smooth, like a body that is pure terrasig)! The feldspar and silica are built-in, producing the glassiest surface I have ever seen (despite this, pieces are not warping in the firings at cone 6). I have not glazed the outside of this mug for demo purposes. I got away with it this time because the Ravenscrag clear glaze is very compatible. But with other glazes they cracked when I pour in hot coffee.

Context: B Clay, How to find and test your own native clays, Mother Nature's Porcleain, Clay and dinosaur country in southern Saskatchewan, Vitrification

Monday 30th March 2020

Red burning, customer-found terra cotta clays tested

We tested four different clays (brought in by customers). One is from BC and three from Alberta. These fired sample bars show rich color, low soluble salts and high density and strength at very low temperatures. L4233 (left): Cone 06 to 3 (bottom to top). Reaches stoneware-density at cone 02 (middle bar). Plasticity is very low (drying shrinkage is only 4.5%). But, it is stable even if over-fired. L4254 (center bottom): Cone 04,02,3,4 (bottom to top). Very fine particled but contains an organic that is gassing and bloating the middle two bars. L4243: Fires lighter and looks stable here (cone 02,01,1,2 shown) but melts suddenly less than a cone above the top bar (well before vitrification is reached). L4242 (right): Hyper-plastic, with 12% drying shrinkage! Already melting by cone 02 (third from top). Achieves almost zero porosity (porcelain density) at cone 04 (#2 bar). Even when mixed with 20% kaolin and 20% silica it still hits zero porosity by cone 1. What next? I'll mix L4233 (left) and L4242 (right), that should produce stoneware density at cone 02 (about 1% porosity).

Context: How to find and test your own native clays, Terra cotta, Soluble Salts, Drying Shrinkage, Vitrification, Bloating

Monday 30th March 2020

How is it possible for the same body to work well at both cone 04 and 6!

White cone 04 bodies are not vitreous and strong and neither is this. But it is plastic, smooth and fits common low fire glazes. How? 15% Nepheline Syenite (also 50% Plainsman 3D, 35% ball clay and 3% bentonite). The unmelted nepheline particles impose their higher thermal expansion on the fired ceramic. Spectrum 700 clear glaze does not craze and does not permit the entry of water (the mug is glazed across the bottom and fired on a stilt). The mug on the right is made from the same clay, it has been fired ten cones higher, cone 6! Here the nepheline is acting as a flux, producing a dense and very strong stoneware (with G2926B, GA6-B glazes). This is incredible! One note: This cannot be deflocculated and used for casting, soluble salts in the 3D gel the slurry.

Context: Nepheline Syenite, 3D Clay, Low Fire White Talc Casting Body Recipe

Wednesday 4th March 2020

Feldspar applied as a glaze? Yes! The way I did it will change how you glaze.

Custer feldspar and Nepheline Syenite. The coverage is perfectly even on both. No drips. Yet no clay is present. The secret? Epsom salts. I slurried the two powders in water until the flow was like heavy cream. I added more water to thin and started adding the epsom salts (powdered). After only a pinch or two they both gelled. Then I added more water and more epsom salts until they thickened again and gelled even better. They both applied beautifully to these porcelains. The gelled consistency prevented them settling in seconds to a hard layer on the bucket bottom. Could you do this with pure silica? Yes! The lesson: If these will suspend by gelling with epsom salts then any glaze will. You never need to tolerate settling or uneven coverage for single-layer dip-glazing again! Read the page "Thixotropy", it will change your life as a potter.

Context: Epsom Salts, Suspending pure feldspar and applying it as a glaze, Pure Custer Feldspar and Nepheline Syenite on cone 10R porcelain bodies, Thixotropy, Powdering, Cracking and Settling Glazes

Wednesday 4th March 2020

A gunmetal glaze I have wanted for decades!

After 40+ years of making pottery I finally have a perfect gunmetal black. It has an incredible silky surface. It does not cutlery mark. It does not craze on anything. It is easy to clean. This is G2934Y with 6% Mason 6600 black stain firing using the PLC6DS schedule. I had to tune it a bit, adding about 15% glossy G2926B, because it was a little too matte on initial firings. But now it is perfect. These are heavy mugs made using the M340 casting recipe (and the casting-jiggering process). The speckled mug was made by casting a thin layer of the speckled version of the slip first, then filling the mold with the regular slip. I used a 40-minute cast to get walls nice and thick!

Context: Cooling rate drastically affects the appearance of this glaze, Gunmetal glaze

Sunday 2nd February 2020

New dealer showroom clay sample boards almost ready (not available retail)

We have new boards for high temperature oxidation and reduction, medium temperature and low temperature. These feature QRCodes for each of the bodies (they go to the information pages for that product on our website, these pages are getting more and more detailed with how-to information). Each body is shown with two glazes. Those glazes have QRCodes at the bottom that will take you to a page with everything you need to know about how to use and get or mix them.

Friday 20th December 2019

Hand-tooling a mug model vs. 3D-printing a mold to cast it

I am creating molds for a 2019 casting-jiggering project to reproduce heavy stoneware mugs manufactured here 50 years ago. I have a profile drawing I want to match (upper left). The solid plaster model on the left was my first attempt at manual tooling. The metal template was time-consuming to hand-make, its contour was difficult-to-match to the drawing and the plaster surface turned out rough and difficult-to-smooth. To make the plaster model on the right I printed a shell (using my 3D printer), poured the plaster in, extracted it after set and then smoothed it on the wheel using a metal rib and trimming tool. It matches the drawing perfectly and the round is very true. 3D-printing is revolutionary for this type of thing! The drawings: I hired someone on Upwork.com to make them for me (using Fusion 360). The shell-mold (to cast the model) on the upper right: I printed that too, in two pieces.

Context: 3D-Printing, Casting-Jiggering, 2019 Jiggering-Casting Project

Friday 13th December 2019

Cooling rate drastically affects the appearance of this glaze

This is G2934Y satin matte with Mason 6600 black stain. The piece on the left was fired using a slow-cool firing schedule (C6DHSC). The schedule for the one on the right turned the kiln off at 2100F (after a half hour drop-from-2200F-and-hold), then it free-fell. The slow cool gives the glaze on the left time to crystallize, thus it is now a stony matte (rather than a satin matte). It is interesting that to this mix of the glaze I added 20% glossy clear, yet it still matted on the slow cool.

Context: G2934Y, A gunmetal glaze I have wanted for decades!, Matte Glaze

Tuesday 26th November 2019

What we see in the park beside the Plainsman plant

The Plainsman Clays factory is right beside a baseball park. A beautiful place in the summer where children play and teams compete. But in the afternoon and evenings the deer move in. And mow the grass! The deer stay around all winter, in this residential area they are away from the coyotes and occasional mountain lion in the nearby river valleys.

Sunday 24th November 2019

This is how much casting slip 10,000 grams of powder makes

To-the-brim the bucket holds 8.8 liters (2.43 Canadian gal, 1.9 US gal). The slip itself weighs 14 kg (30 lb). It has a specific gravity of between 1.75 and 1.8. The slurry was power-mixed in a larger bucket.

Context: Slip Casting, Deflocculation

Friday 22nd November 2019

Find thousands more like the following: Use the search field at the top of the page at the Digitalfire Reference Library.

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