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This is our new site as of Aug 25, 2020. It will help us to serve you better. PLEASE NOTE WE ARE IN THE PROCESS OF PUTTING VANCOUVER ISLAND PRICES IN OUR NEW CATALOG. We are configuring and adapting it in the coming weeks for better information and better functionality on smartphones. Stay tuned for more services to come via this site as well.
Click the links to the left to get information and pricing on our products. Click the "Plainsman Data Sheets" for details information on the use and Plainsman clay bodies and glazes. The blog below is intended to help you with all manner of technical issues in ceramic hobby production, these posts come every few days, so check back often.
Technical Tips Blog
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
Trafficked online recipes waiting for a victim to try them!
You found some recipes. Their photos looked great, you bought $500 of materials to try them, but none worked! Why? Consider these recipes. Many have 50+% feldspar/Cornwall/nepheline (with little dolomite or talc to counteract their high thermal expansion, they will craze). Many are high in Gerstley Borate (it will turn the slurry into a bucket of jelly, cause crawling). Others waste high percentages of expensive tin, lithium and cobalt in crappy base recipes. Metal carbonates in some encourage blistering. Some melt too much and run onto the kiln shelf. Some contain almost no clay (they will settle like a rock in the bucket). A better way? Find, or develop, fritted, stable base transparent glossy and matte base recipes that fit your body, have good slurry properties, resist leaching and cutlery marking. Identify the mechanisms (colorants, opacifiers and variegators) in a recipe you want to try and transplant these into your own base (or mix of bases). And use stains for color (instead of metal oxides).
Context: Trafficking in Glaze Recipes, Metal leaching from ceramic glazes: Lab report example, Tried and True recipes. Really?, The first of 15 "Fool-Proof Recipes" wrecked my kiln shelf!, Mechanism, Base Glaze, Limit Recipe, Glaze Recipes
Friday 11th September 2020
Mason stains in the G2934 matte base glaze at cone 6
Stains can work surprisingly well in matte base glazes (provided they are not too matte). Stains perform differently in a matte host glaze. The glass is less transparent and so varying thickness do not produce as much variation is tint. Notice how low many of the stain percentages are: yet most of the colors are still bright. A good reason to minimize stain concentration is to avoid leaching. We tested 6600, 6350, 6300, 6021 and 6404 overnight in lemon juice, they passed without any visible changes. It is known that MgO mattes, like this one, are less prone to acid attack that CaO mattes. A down-side to this matte mechanism is that chrome-tin stains do not work (e.g. 6006), this is because this does not have the high CaO content needed in the host glaze to develop the color. The inclusion stains 6021 and 6027 work very well in this base. As do the 6450 yellow and 6364 blue. And the 6600 produces an incredible gunmetal black. The 6385 is an error, it should be purple (that being said, do not use it, it is ugly in this base).
Context: Mason 6021 Red Stain, G2934, Stain 6201, Stain 6134, Stain 6100, Stain 6006, Stain 6020, Stain 6666, Mason 6600 Black Stain, Stain 6500, Stains Mason, Mason 6027 Stain, Dipping Glaze, Ceramic Stain
Wednesday 9th September 2020
Mason stains in the G2926B base glaze at cone 6
Stains are a much better choice for coloring glazes than raw metal oxides. Other than the great colors they produce here, there are a number of things worth noticing. The percentages may be lower than what you think would be needed, stains are potent colorants. Staining a transparent glaze produces a transparent color, that means it is more intense where the glaze layer is thicker. This is often desirable in highlighting contours and designs. If you add an opacifier, like zircopax, the color will be less intense, producing a pastel shade the more you add. The chrome-tin maroon 6006 does not develop well in this base (alternatives are G2916F or G1214M ). The 6020 manganese alumina pink is also not developing here (it is a body stain). Caution is required with inclusion stains (like #6021), the bubbling here is not likely because it is over fired (it is rated to cone 8), adding 1-2% zircopax normally fixes this issue.
Context: Mason 6021 Red Stain, Stains Mason, G2926B, Concentrate on One Good Glaze, Stain 6404, Stain 6385, Stain 6450, Stain 6364, Stain 6300, Stain 6100, Frit VO 6134, Stain 6201, Stain 6134, Stain 6500, Stain 6006, Stain 6666, Mason 6600 Black Stain, Mason 6027 Stain, Base Glaze, Ceramic Stain, Colorant
Wednesday 9th September 2020