As I may have mentioned before, buying the pugger/mixer was probably the best decision I made last year. It has made my life easier in so many ways. However, it has made things more difficult in one way: it is hard to keep track of all the claybodies that go into the kiln. Especially after they are made into something and drying on the shelves, it is very difficult to tell them apart.
When I fired with the gas kiln, stuff didn’t pile up all that much, because I fired frequently. Now with the wood kiln getting fired 3 times per year, things tend to stack up, and labeling is essential to avoid hideous mishaps. I try to keep types of clay consistent from wareboard to wareboard and label each board, but packing pots in the kiln to bisque them means losing the labels and taking extensive notes, because bisqued clay looks even more similar than green.
The other day, I was wishing I had a way to label the pots better, then it came to me: a labeling app on my smart phone with which to label photos in my gallery. I downloaded a free app (there are lots of different ones), and viola!, pictures taken of my bisque load shelf levels are now accurately labeled and instantly backed up to my home network, so I know I won’t lose them.
Now if significant time passes between firings, or just unloading a bisque, I can refer to my pictures to figure out what everything is.
Here are the first of a bunch of water jars and flower vases that are going into the kiln this early fall. I really needed some practice coiling, paddling, and collaring in necks on the kickwheel and 船徳利 funadokkuri (boat flasks) are the perfect shape for it. Traditionally these were used as flasks for oil, etc. on boats. They needed to be hard to tip over, hence the wide flat bottom. Now they are mostly used for flower arrangements.
All of the water jars will have wooden lids made for them. I’ve done one or two in the past with surprising positive response from viewers/customers. The lids are fun to make, since they are a non traditional item, you can play around a bit with them. I’ll post some lids later on, if the pots make it through the firing.
3 boat flasks and one taller crane necked flaskwater jars. any marks in the clay need to be pretty over the top, because the glaze covers them over for the most part.lug and lip detailmore jars, a couple with ‘nail heads’ added, instead of lugs. You sometimes see these on tea cups and food dishes in Karatsu ware.
all together now… The tallest flask is about 28cm tall,dry.Karatsu meets pueblo water jar, with kneeling, bowing tea person receiving tea. This started as a lug and sort of went bananas from there. This could be one of those things where I later slap myself.Tall necked vase with two pairs of tea people bowing.Karatsu meets pueblo water jar. sorry for the order here…Lug detail. I really must have wanted to drink tea that day.boat flask with porcelain additions. Here’s the big question: Will they pop off upon drying?tall necked flower vase with lugs, (finally some normal ones)
Well, time to sit down with the last firing and figure out what went wrong, and what went right.
Firing and packing: Great. With this firing I figured out, FINALLY, the proper exit flue volume to use. And with it, the proper packing procedure. The kiln climbed steadily, without effort, for 45 hours and the flame in the front chamber reached front to back really nicely. It turned out to be a fairly even gradient from front to back, from cone 13 in front, to a good melted 8 in back. No sidestoking necessary.
I am going to go back to using a pyrometer for the next firing, because this firing got very reduced. I think the stoke intervals were too close, and a pyrometer may help me get a better idea of temp climb timing, and when each cycle goes into oxidation.
At one point, when we switched to stoking the 2nd chamber, the temp just started dropping. You could tell from the sound and color of the kiln. I jabbed a pyro into a peep hole and it told me right away that I was stoking to frequently. After the flame had receded into the chimney and peepholes, and the roar had died away was when the temp really started climbing in the chamber. I had been stoking when the flames receded and the kiln quieted down, but once I started waiting rather for the temp to start dropping after the rise, the kiln got back on track. This rise took longer than I imagined, sometimes up to 10 minutes. Had been stoking waaayyyyyy too much.
This firing was a watershed moment for me, regarding packing, air, and stoking. I think next time will finally be the load that makes us all smile.
Glazes: Glazed ware in the second chamber turned out really nice. Reduction was still too heavy, but we got nice surfaces. Still, I won’t aim for that in the future. Madara glazes were too yellow for my taste. The first chamber glazes were so reduced that whatever their intended color, everything turned out a semi matte green, from the excessive iron pulled from the body saturating the glaze and crystallizing. I think the stoking interval will fix this problem.
Clay body: Oops. Here is where the shit hit the fan. Too much iron, especially considering the temp and amount of reduction that happened. The clay I used for the large pieces has too much iron for that type of firing environment, which is why they almost all collapsed. Having worked with a gas kiln for so long, it is hard to get out of the mindset of adding iron rich clay to other whiter bodies in order to get a desired color. The white clays in this area have enough iron for good color in a wood kiln. I keep forgetting that, but perhaps the shock of this latest meltdown, and the subsequent pain of shelf grinding will serve to jog my memory whenever I’m mixing clay for the wood kiln.
We got this off the shelf in one piece! The attached cup sits level when you set the piece on a table, so great for sashimi and sauce or condiments.The Fall of IcarusArm detail
Well, didn’t quite make the Feb. 29 date for firing the kiln. My wood ash supply ran out and it was hard locating more and getting it tested. Also had the top element go out on my electric kiln, so couldn’t use it for bisquing. Finally got that stuff done, so was able to mix up glazes and get to glazing/loading. Got the rear setting done this evening. My shipment of cones from Axner came in the nick of time, so here are the new self supporting cones in action. I have decided that I LOVE self supporting cones…
The rear setting done, finally. A total of 115 pots, give or take.
I mentioned that I’d run out of glaze ingredients. Some testing was required to ‘find’ my glazes again. This glaze is tough because it goes clear if too thin, or is too white and runny if too thick. Also, I’ve been trying to tweak my Madara to more closely resemble that of the old Karatsu pots, circa 1580. Theirs went on thin, but kept its color. A lot of silica, probably. Here are two test tiles with Madara glazes. They were fired in the tiny test kiln and you can see they went pretty clear, because they were directly in the flame path. The tile on the left is the tweaked version, with more silica/rice straw ash and less mixed wood ash. I think it is pretty close to what I want, and will have more color when not fired in the tiny kiln with that concentrated flame, and gets a slow cool.
two test tiles with variations of Madara Karatsu rice straw ash glaze.
This upcoming firing we will have our first attempt at hikidashi, which means pulling pots at high temp and letting them cool quickly, or quenching them in water or something flammable such as rice hulls, sawdust, etc… This time, all of the hikidashi will be hikidashi guro, or black glazed ware pulled at temp. In the picture of the rear setting above, all of those pots with the red glaze are going to be yanked out. From the side port, a pair of tongs about 1 meter long is just about long enough to get most of the ware. For pulling from the front stoke, tongs are just too short, so I spent some time this afternoon making a new tool. By drilling a hole into the side of the test kiln, I converted it into a simple forge. I took round steel stock and repeatedly heated it and hammered it to flatten the end then used a hammer and chisel to split it lengthwise from the end. A little creative hammering gave me a two pronged fork shape for scooping up bowls and pulling them out the front of the kiln. Can’t wait to give it a try.
New fork tool for pulling pots from the front stoke
The concrete combined with the sump pump is doing its job admirably. I took these pictures this morning after a night of med/heavy rain (but nothing close to the storm last evening). Water has started to seep in places, and since the part in the foreground is not under cover, some rain falls right in, but that will only be a problem during firing. Last firing there was some rain and I strung a tarp down at an angle from the cover which worked alright, if not very elegant.
Here are the pictures of everything when it is moderately wet. Water is collecting around the edges of the concrete, but even in the heavy rain yesterday, was unable to reach the top. The sump pump has activated at least once, judging from the wetness of the concrete in the sump. When the top float goes up the pump turns on, and when the bottom float goes down, the pump turns off. It takes about 25 seconds to pump the water out, MUCH faster than the previous pond pump. The sump form collapsed under the weight of the concrete so is not the oval I had planned, but looking at this pic now, the sump really resembles a fish, don’t you think. Especially with the corrugated edges where the tail would be.
I installed a tube into the concrete through which to run the pump hose and power line, so it would be hidden. There is a drain about one meter to the right of where the hose and line emerge. Once a trough is dug between the two, the hose will be almost hidden. A trough will also prevent water from traveling along the surface toward the workshop path and kiln.
The unfortunate casualties of all this improvement are the frogs, and I am going to miss them. Hopefully they will find other low wet areas in the yard to hang out.
