New Host

The old server at ltc.umanitoba.ca was closed down and the blog moved to this host. We’re still working on getting the theme fixed, so for the mean time, it’s a generic picture on top.

November, 2011:  The new website is, for the time being, at
http://home.cc.umanitoba.ca/~grimmer/Home.html

 

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Hors d’Oeuvres, Poplar Firing

As promised in the last post, I have images of some nice pots fired with Poplar instead of the usual Tamarack. Previously, I had mentioned that I thought the poplar we were getting was Populus tremula, or Trembling Aspen, based on the widespread occurrence of that tree here. I’m going to revise that assertion and say the wood is more likely Populus balsamifera, aka Ontario Balsam Poplar, due to the bark patterns and the alluvial location of the harvest forrest east of here. I could be wrong.

Anyway, the Poplar we get doesn’t have a terribly high heat value compared to Tamarack (Larix laricina), though it builds a better ember bed and seems to have a softer flame, better able to evenly heat the back of the kiln and to wrap around pots in the chamber. Firings with Poplar see much less of the wind-side/lee-side effects of the Tamarack firings. Our last firing with Poplar was 56 hours, but for this Open House weekend fire we kept it to 33 hours.

Also, notice the much lighter and more varied colors from the Poplar ash and the much more varied surface effects from this wood. The ash color can be almost dead white: John Balistreri calls it, “white snot.” Regardless, it seems able to produce the full range of colors and effects that I am looking for. The pots from this firing have stunning opaque white drip lines over charcoal black grounds with glassy green islands between. It’s really a sight to behold.

The first pot is a Chawan that I call Rain. It is standard stoneware with a thin coat of Schiller slip (EPK, Goldart, OM#4). The results are nothing short of stunning. This pot was fired in the throat of the kiln, but was protected by a brick and so did not receive the full brunt of the flame, just plenty of fine ash. Notice the light-colored ash beads on the warm yellow and orange ground transitioning to the cooler ground to the right. The far rim has good warm coloration as well.

Bowl for the Tea Ceremony, named "Rain"

Here’s the back side of “Rain,” fully illustrating the varied effects of Poplar ash on a small pot. This side has much cooler colors than the front, but there’s a nice white cascade over orange and brown on the far rim from the flame curling over the lip of the pot.

Back side of the teabowl named Rain

The second pot in tonight’s lineup is an ovoid vase, about 14 inches high, thrown with a standard all-Grolleg Kaolin porcelain body. The inside is lined with a white shino-type feldspathic glaze (Great White shino), but there’s nothing applied to the outside of the pot. (I suspect there’s a little soda deposition from the liner glaze, though.) This side obviously faced the firebox, and there’s an enormous cascade of white ash glaze to show for it. The top third of the vase shows signs of late-deposition coarse ash in the rough texture. This is material that landed on the pot in the last hours of the firing that never had the time to melt.

Vase in the shape of a football.

Ovoid Vase.

Three more views of this pot follow. The rich, charcoal-gray background from the heavily reduced porcelain is noting short of spectacular in my book. Pay special attention to the yellow-green crystals floating in the glossier areas at the bottom of the pot on the back side.

Here’s the right side, showing the dramatic transition from front to back.

Shows both front and back

Ovoid vase, Right side.

Here’s the back of the Ovoid vase, showing the effects of much finer ash deposition. There’s more color here, but it’s subtle and within the cooler end of the color spectrum.

shows the much finer ash deposition.

Ovoid vase, back side.

And here’s the left-rear side of the vase. This side was quite close to the wall of the kiln, so you don’t see the cascade of white from the front over here as you did on the right side view.

Left side of Ovoid Vase.

Ovoid Vase, Left side.

Finally, a little detail shot of the green crystals near the foot of the vase. They look like lilly pads. Wow.

Lilly pads.

Ovoid vase, reverse. Crystals growing in the glaze.

The last pot for this evening is a large porcelain bottle, also made with a standard Grolleg porcelain. This pot was right in the front row of the firebox, and bears the scars of the ember bed piling up against the lower portion of the body and neck. The erosion line is quite evident, as is the heavy accumulation of late-deposited, unmelted ash on the top of the neck.

Fired in the front row!

Porcelain bottle with heavy ember buildup.

Here, we have the right side of the bottle. The drips are quite white, indeed, especially over the nearly-black body.

nice white streaks!

Right side of Porcelain Bottle.

Here’s the back. Notice the effects of the fine ash deposited here. Great colors.

light ash

Porcelain Bottle, Back.

And here’s the right side. More dendritic rivulets of white ash over the black ground.

more fine white ash.

Porcelain Bottle, Right Side.

Lastly, a couple of macro shots for your amusement. Here’s some encrustations.

crunchy!

Crystals growing in the glaze on the back side of the bottle.

Lilly Pads.

That’s all for tonight. Tomorrow afternoon, I hope to photograph some pots that have been sitting around, waiting for me to grind the slag off the bottoms. I’ll try to post the good ones over the weekend.

-swg

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Hors d’oeuvres

Here’s some hors d’oeuvres from two firings at the end of the 2010 term. The firing in March was taken up almost entirely by chili bowls for the students’ end-of-the-year fundraiser at the School of Art open house. We had about 250 bowls for this firing plus the usual student work, so I raided some of the older silicon carbide gas kiln shelves to have enough. I had made some chili bowls with the students on the Saturday throwing party and got distracted making a few boards of Chawan (Tea Ceremony bowls) as well, and so those went in to this firing also along with some stoneware bottles I had made one morning when the studio was quiet.

The Chawan are all glazed with a variation of Shark Skin shino, which I call Great White shino: 80 Neph Sy, 20 EPK, 2 Soda Ash. It’s pretty subtle as shino-type glazes go, but it does some nice things if you pay attention. (Substitute salt for the soda ash, and you have Ian Currie’s Shino #2.)

This first Chawan has nice ‘rolling hills’ marks on the front. It was in the front set of shelves facing the firebox and there’s not much ash build-up on it at all save the almost-clear green glass near the bottom. I attribute this to the fact that we used Tamarack, fired efficiently, and that the white glaze is relatively indifferent to atmospheric effects.

Teabowl with rolling hills marks

On this second Chawan, you can see a little blushing from the clay underneath and some pinholing in the glaze that is just a hair away from crawling.

Teabowl with Peach-colored blush

OK, now here’s a couple of images of a bowl with very interesting crawling that makes me think of a net stretched over the bowl or perhaps soap bubbles. I don’t like to associate a drinking vessel with soap, so it’s called ‘Net’.

Teabowl with crawling glaze.

The back side of “Net” showing a little skin and you can see more clearly the brush marks of the stoneware slip I applied. For those of you keeping score, it’s Schiller slip: 33 EPK, 33 Goldart, 33 OM4.

Back of Teabowl named "Net"

The foot-view of ‘Net’ shows the high velocity of this firing. There’s just about no flashing on the downwind side of the foot ring. You can also see the different glaze response from one side to the other.

Foot of the bowl named Net

Chawan, 'Net.' View of foot ring

Now for a few from the throat of the kiln. Pots from this area look very much like they were subjected to multi-day firings, though this one was just 33 hours.

Bottle with dumbbell shape.

Dumbbell bottle 1

These pots are thrown with minimal use of the rib, all in one go with about 5 pounds (2.2kg) of clay. It’s the same body used for the Chawan, but I wedge in some coarse local feldspar and sawdust to give the body a little texture. This second one was in the second tier of the firebox, so there’s more fine ash deposition and no ember line.

Stoneware bottle in the shape of a dumbbell.

Dumbbell Bottle 2.

There’s a thin wash of a shino slip on these, but most of what you see here is the effects of ash and flame. The crusty ember line is quite evident on these, as is the area of intense reduction below it. Look for the subtle iron reds, blues, and charcoal gray.

Stoneware bottle with lugs on the shoulders.

Dumbbell-shaped bottle with Epaulettes.

Stay tuned later in the week for a short installment of pots fired with Poplar instead of Tamarack. The results are much more dramatic!

-swg

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October, 2009 Firing.

We did a firing in October after our visiting artist, Tamura Shizuo, left us with a bunch of really nice pots, including a few exceptional Chawan
(I’ll post images of these soon), and I had a stack of work from the summer waiting to be fired. We had been bugging our wood supplier, Myron, for some Aspen (Populus Tremuloides) and he brought us a nice load of extra-long slabs plus a one-third load of the usual Tamarack. Aspen has a lower heat value than Tamarack (Larix laricina), but produces some really nice colors in the ash.

Blue Dome Vase.

Blue Dome Vase.

I had been wanting to do a longer, cooler firing, so the time seemed right with this big pile of Aspen. We loaded the kiln in the normal fashion but fired for 56 hours instead of 32, and held the temperature in the cone 6 range for a day before climbing to cone 9, with cone 11 in the throat.

Blue Dome Vase.

Blue Dome Vase 2.

You can see these vases were in an area of slight oxidation; there’s a yellow-green blush in the blue celadon. Normally considered a fault, in this case it’s a nice variation in color.

The ash colors are much more varied with the Aspen than with Tamarack, especially on the pots near the firebox. Instead of Tamarack’s mostly opaque yellows, we got a lot more golden yellow, orange, green, and purple colors. Very nice indeed! Also the ash and the glazes are much less runny at the lower temperature, which stands to reason. I prefer less grinding to more.

Here’s some of those nice Aspen colors on a bowl.

Medium Blue Dome Bowl

Medium Blue Dome Bowl

Foot of Medium Bowl

Foot of Medium Bowl

Inside of Medium Bowl

Inside of Medium Bowl

There was only one problem with this firing: we seem to have gone up to high temperature on the last night, come down a ways, and then went back up on the last day. Some of the pots (10%) have that distinctive wrinkling in the ash that can be crunched with the fingernail. On most it’s very minor, but there are a couple of pots that will have to be cleaned up and a little glaze fired back on the bare spots. Next firing, I’ll make sure we all keep an eye on the temperature so it doesn’t go too high too early.

You can see the wrinkling on the knob of this jar.

Blue Dome Jar with Hexagonal Base

Blue Dome Jar with Hexagonal Base

I’ve been doing this Cross-Star pattern (taken from Islamic tile) on pots like this Teabowl for a while now and still enjoy it. You can tell there’s quite a heavy ash buildup on this one, especially by the celadon glaze cascading over the bump at the shoulder. If this were Tamarack ash, the translucent golden-yellow ash glaze on the right side of the pot would be an opaque light yellow. Much nicer with Aspen.

Teabowl with Cross-Star pattern.

Teabowl with Cross-Star pattern.

Here’s a really great illustration of the color possibilities with the Aspen. That purple drip in the middle of the frieze would never happen with Tamarack. Also, note the delicate streaks in the glaze, both inside and outside the pot.

Blue Dome Teabowl.

Blue Dome Teabowl.

In addition to the porcelain work, I’ve been playing with a couple of dark stoneware bodies. One is quite “porcelaineous,” with two kaolins, two ball clays, Neph Sy, Flint, and 5% Newman Red as the iron source. The other is closer to what one would expect in a stoneware, with Hawthorne Bond, Goldart, Foundry HIll Cream, Neph Sy. It’s also got Newman Red in it.

These two teabowls and the coffee cup are made from the ‘stoneware.’ Where the flame hits it hard, it has a richer brown color, tending toward chocolate.

Pair of Teabowls with Cross-Star pattern and inlaid glaze.

Pair of Teabowls with Cross-Star pattern and inlaid glaze.

Coffee Cup with Cross-Star pattern.

Coffee Cup with Cross-Star pattern.

These teabowls are made with the more porcelain-like body. The difference is subtle, but the stoneware-type body is more toothy and open in appearance, especially under the foot where the atmospheric effects are minimized. The porcelain-like body is lighter in color, tending toward grey in the absence of ash, and a more orange-brown where the flame fits it hard.

Pair of Teabowls with Cross-Star Pattern.

Pair of Teabowls with Cross-Star Pattern.

We fire again in a week, and so more results are coming.

Steve

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