The Final Coat

The mud that I ordered came on Monday, and even though the kiln is still warm, I’ve started applying it. Actually, it really helps it harden faster and stay in place. It will crack pretty badly but it would anyway, and I plan to go back later and fill in cracks and joints later anyway. What you see here is one ton of cob, which is composed of unrefined red mountain clay, decomposed granite sand, and straw. I don’t know the proportions, but it shrinks about 3% from wet to dry.

Now that the first ton is used up, I need to order one more, and that should be enough to finish the job, then have leftovers for crack mending and a finishing coat, plus enough to insulate the new pizza oven that we are building from leftover kiln bricks.

While working this morning my twisted mind came up with this, you may be familiar with a slightly different version:

“I held the spade in trembling hands
Prepared to slap it on but just then the phone rang
I never had the nerve to add the final….    coat. “

I know, really bad…. Sorry.

Finished firing

After taking things slow for about 12 hours, we took the kiln up to cone 11 over the next 24. Finished up at about 4am Saturday morning, quite a bit earlier than I had planned. Earlier in the firing, I had thought it would take longer, because the kiln was not really responding to the stoking and seemed to be reducing strongly, making me think that I’d perhaps closed the flue channels a bit too much prior to firing. However, after cone 9 started to finally go down, we started to get that great growling roar following every stoke, and pretty soon cone 11 was bending. Here are some sequential pictures from the firing.

Nakayama kun stoking under the grates during the preheat, we kept it at around 250C or under for about 12 hours.

 After we got to about 1000C, we started getting smoke.

 The castable on the second chamber splitting along the line I was hoping for….

 Cone 11 is half over and Nakayama kun is starting a stoke.

 It almost feels as if the flames will push the stoke cover away from the kiln wall. Without the rod propped against the cover, the flames come out in all directions.

 The chimney after the stoke, it is about 3 am.

 After I clammed up the kiln for good, there was still enough fuel in the form of embers to keep burning pretty strongly. I was  a little worried about inadvertently over reducing when I saw this. Not sure if this was good or not, I decided to open up the rear damper again and let some of those excess calories exit the kiln, however the extra oxygen just cause the temp to start rising again and after about 10 minutes I shut the damper again. By then the flames subsided quite a bit.

 Here is the door all mudded up, because there was a good 5mm space all around the door where the kiln had expanded.

Notes from this firing:
-I may need to open up the flues a bit to get some more air flow.
-The insulating castable on the front wall and rear chamber is AWESOME! Even at cone 11, I could keep my hand on the castable surfaces.
-Pyrometers are not to be trusted. The highest reading I got the entire firing was 1056C, and this was when cone 6 was about half over. Moreover, as the kiln got hotter the range of the pyrometer readings actually became lower and lower. Not sure what this means yet. I’m thinking right now that the pyrometer is not extending into the kiln far enough, and pretty much is just responding when directly exposed to flame.

We will be unloading on Wed. I will post pictures shortly after… I can’t wait…

Taking it slow. . .

It is three in the morning and the fire is burning along nicely . A lot of greenware in the kiln this time, so we are very relaxed right now, going slowly. It is a nice feeling to be the only one up this time of the morning, I can hear the faint intermittent roar of cars on the highway in the distance, but other than that it is just the crackle of the fire. Later today, it is going to get pretty hot and busy, so just enjoying the moment for now.

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waterlogged

It continues to rain here, rained cats and dogs all night. This was the state of things in the morning:

You can see the shelves laying across the door above the primary air. The second one down is the same level as the kiln floor. Pretty darn close to flooding, but safe. It rained A LOT, all night, and I’m not sure why it stopped at this level. It usually stops around here so there must be some sort of drainage happening that keeps it from coming higher.

I am somewhat encouraged by this because it means I can finish loading today and probably not have to fear that pots will be floating out and about tomorrow morning.

Oh, and there were no dead animals in my kiln this morning, always a plus.

Loading it up…

I started loading the kiln on Sunday, but didn’t get very far. By Monday evening the rear setting was finally finished. For some reason the rear setting is time consuming. Today (tues) I started the middle setting and got it about half finished in 2 hours.

Here is the rear setting going in:
Fairly low temp glazes at the bottom rear. That rear bag wall has holes along the bottom for a bit of flow, but I want to see what I get there as far as temp and reduction with limited flow. Most of the rear setting stuff will mature at Orton cone 6-8.

 The plates on the floor should get nice and covered in embers. The top left, behind the beer mugs, has another large jar that is not very visible in the picture.

It rained all night monday night and this is what greeted me in the morning:
The water missed the mattress by about one cm. To get an idea of the depth, look on the left side and you can see the shovel handle.

 There is a black spot on the blue mattress and if you look closely you can see it is a frog. Unfortunately, he is dead. One of the neighborhood cats has taken to having his midnight snacks in my kiln. I wish he/she would clean up after eating…

 All pumped out now, but with the continuing rain, I have to turn on the pump frequently. I leave my sandals in front of the kiln when I go in and load. If I don’t pay attention I could get stranded in the kiln and my shoes would be floating around in that front area. So, I load pots and glance back now and then to check the water level, plugging the pump in when it gets too high. I REALLY need one of those automatic sump pumps so I don’t have to keep switching it on and off manually. The water made it into the firebox Monday night, but not up onto the front floor of the kiln yet. We’ll see if it gets any higher by tomorrow (Wed) morning.

We are expecting rain through Thursday, so I’m a little worried about finishing the front setting on Wed evening, then waking up Thur morning to find all the pots sitting in and inch of water.

Even with the front area pumped out, the wind has been blowing the rain in, making it difficult to load the kiln. I nailed up a tarp to cover the entrance area. Later in the year, I’ll extend the roof properly to keep things dry.

One last item of interest: The company that manufactures Seger cones (Japan uses Seger cones rather than Orton) was in Fukushima, and was apparently seriously affected by the recent disaster. Consequently, Seger cone prices have tripled. They were 200 yen (about $2) each to begin with, but can you imagine paying $6 for a cone?! I had trouble shelling out $2, so I switched to Orton a couple years back. It is still WAY cheaper to pay shipping on Orton cones from America than pay for Seger cones here, even when they were practically a steal at $2 each.

The maiden voyage of the Uber-Blend 5000 Turbo

 I acquired this piece of machinery, the Uber Blend 5000 Turbo, from a kindergarten that had used it for mixing large batches of powdered milk. It is basically just a very heavy motor suspended beneath a large reservoir, driving some wicked looking 4 inch wide mixer blades. It is so heavy that it needs its own frame to support it and stand it up. When mixing is done, the entire reservoir can be tipped down to decant the contents.

I’ve been doing lots of glazing this last week, and decided at the last minute to test a new glaze in the upcoming firing. This glaze is basically just stamped feldspar and ash, in a 9 to 1 ratio. Anyway, mixing up this stamped feldspar is always a time consuming, tiring affair, because it comes in cakes straight from the filter press, and is like a stiff clay. Getting this to melt in water is tough. If you let it dry completely, as I have started doing, it gets rock hard, but is easy to break into smaller chunks. I’d been slaking these small chunks in water over a period of days or weeks to prepare it for thorough blending with a drill mixer, but this time I had the Uber-Blend 5000 Turbo!

Here are some of the chunks of Taishu feldspar. These were the smaller ones, measuring a couple of cm across. The largest chunks were up to about 7cm.

The Uber-Blend 5000 Turbo, in all of its sleek elegance. It is an absolute chick-magnet. With this baby parked in the studio, who needs a Lamborghini?

This is 9kg of spar and 1kg of ash turned almost instantly to smooth, silky glaze, requiring NO screening. There were a few tiny lumps left after the initial 30 seconds, an additional 5 minutes of uber blending and they were history too…

And in conclusion:  IN YER FACE, Magic Bullet!

Happy potting everyone.