The pictures below are from a Concordia Fine Arts year-end off-campus Ceramics show, "C'est Rare, Cerart". The piece is called "Because We Like It", and it's a collaboration between me and my friend Garnet Muething.
Above: The "lichens" look like they've been glazed with Cranberry Rust, and the bowl at left was glazed with a layer of matte white with the rim dipped in Cranberry Rust.
The "collaboration" was not a strictly pre-planned one. Garnet and I had met and become friends because we were both take ceramics courses; she was a level ahead of me, and thus had more technical privileges (such as being allowed to make her own glazes). So at some point she offered to split a batch of porcelain with me, and so I got my first opportunity to work with something other than stoneware or earthenware. Garnet was using a special stoneware recipe as well as making her own porcelain.
Above: The lichens have been dunked in a grey-"hazel" glaze made by Garnet, possible with rims in Cranberry Rust. The bowl on the left was glazed matte white and the rim was dipped in "Raisin", a dark bluish-purple glaze made by our co-student Geneviève. It was part of the Cone 11 firing, hence the extreme effects.
We ended up making the clay, bisque firing our porcelain pieces, and then using the same glazes together (several of which were glazes Garnet had made), so although our pieces were for two separate projects, we eventually got the idea of combining them into a third different project and proposing it for the year-end exhibition. These pictures show parts of what we came up with, which we called "Because We Like It". I liked Garnet's project names--she had another one called "You Know You Want To", as I recall.
These lichens were dipped in matte white and then Cranberry Rust; the bowl is a Celadon, oxidation-fired (hence yellow, not green).
All my bowls and (I think) all Garnet's lichens--the name she gave to the little tube-like, organic-looking sculptures--were made with "sculpture" porcelain. We made this in large batches and stored it in our lockers until it ran out and a new batch had to be made. There's a long story here about me accidentally discovering that porcelain improves with fermentation (something the ancient Chinese already knew), but I'll save it for another blog post ;-)
Above: A Hazel bowl with clear blue inside. fired to Cone 9; Garnet's lichens are Hazel, possibly dipped with Cranberry Rust rims.
Porcelain is a clay that can be fired to very high temperatures without melting (though it does "vitrify"). So the glazes we used were for high-firing, and the highest temperature we were permitted to fire to was Cone 9, around 1,280 degrees C (pyrometric cones, designed to melt at certain temperatures, are placed inside the kiln and used to determine when the correct firing temperature has been reached).
Glazes when fired to high temperatures "behave" in a much less stable way than when fired to a lower level. This means that glaze effects are much more difficult to predict than they would be at a lower cone (04, for example, is a low firing temperature appropriate for terra-cotta, around 1,060 degrees C.). It's also harder to achieve "warm" colours (red, yellow, orange) at high temperatures, and to produce "bright" colours in general. That's why the brightly-coloured pottery you see in many stores is likely to be less durable--because it probably wasn't fired to a high temperature.
A nice view of my best "exploding star effect" bowl (Cone 11 firing). The lichens have Cranberry Rust (red ones on the right) and the Hazel/clear blue combo (at left).
Ceramic pieces are usually fired twice when they're glazed, as I explained in this post. After these pieces went through the bisque firing, they were dunked in one or more liquid glazes--many of the interesting effects come from combinations of glazes rather than one glaze on its own (though there can be considerable variation even with one glaze, especially in a reduction firing).
One of the glaze firings went over-temperature by what looked like at least a full cone, but since the third cone was almost fully melted I assumed the firing had reached the equivalent of Cone 11, about 1,315 degrees C. (insert Spinal Tap jokes here). Fortunately for Garnet, none of her work was in that firing. I'll never forget the process of unloading the kiln, during which I learned a new French swearword (uttered by one of the other students when he saw the mess-!). The glazes had run all over the kiln shelves and in spite of kiln-wash, a lot of the pieces had fused themselves to the shelves, which of course had to be cleaned.
Yet from this spectacular screw-up came some of my most interesting and beautiful pieces, which I never would have achieved otherwise since the temperature limit was technically Cone 9. Because the glazes over-melted, they ran together/blended in unique ways according to the types of glazes and the shapes of the bowls to which they'd been applied. And in spite of my sloppy throwing technique, none of my bowls collapsed from the heat.
Yet from this spectacular screw-up came some of my most interesting and beautiful pieces, which I never would have achieved otherwise since the temperature limit was technically Cone 9. Because the glazes over-melted, they ran together/blended in unique ways according to the types of glazes and the shapes of the bowls to which they'd been applied. And in spite of my sloppy throwing technique, none of my bowls collapsed from the heat.
All three bowls visible in the picture above came out of the Cone 11 firing. At the back, the blue bowl was dunked first in matte white then edged with a clear dark blue glaze. The middle bowl was matte white with a Cranberry Rust rim (compare it to the other one above, with the same glaze combo; which was fired to regular Cone 9. Quite the contrast!). At the front is a bowl dipped in Garnet's Hazel glaze, edged with what could be Geneviève's Raisin or Cranberry Rust (again, it's hard to tell). The lichens in the centre are all fired to Cone 9 with Cranberry Rust; those at left were Hazel with dark clear blue.
That white/orange "starburst" bowl, one of the best from the firing, had attached itself solidly to the kiln shelf; I remember feeling afraid that I'd lose it (i.e. it would have to be broken off the shelf in chunks). Then a fellow student took the shelf, put her foot on it, grabbed the bowl and yanked it off in one piece--taking a chunk of kiln-shelf with it! I had to use a grinding wheel on it for about half an hour before the bottom of the bowl was flat again. Good times.
That white/orange "starburst" bowl, one of the best from the firing, had attached itself solidly to the kiln shelf; I remember feeling afraid that I'd lose it (i.e. it would have to be broken off the shelf in chunks). Then a fellow student took the shelf, put her foot on it, grabbed the bowl and yanked it off in one piece--taking a chunk of kiln-shelf with it! I had to use a grinding wheel on it for about half an hour before the bottom of the bowl was flat again. Good times.