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Firing Log

ancient kiln | 21st century logbook

January 31, 2009

I’m Happy with the 11th Firing

Filed under: anagama, 11th,Firing,glaze,Pieces — odin @ 9:41 pm

I think the 11th firing worked out quite well.  I outlined my firing plan earlier this week, and now, some of the results are available in the photogallery.

It was a very hot firing — cone 11 laid flat front to back (I don’t have any higher cones).  However, I think getting it so hot is detrimental in that the glaze tends to run completely off vertical pieces.  There are two problems with this — first, the glaze is gone, and second, foot grinding is a huge chore.  Perhaps in future firings I will work on controlling the maximum temperature to no more than cone 11.

What was most excellent however, is that I avoided the gray-gunk I mentioned previously by not overstoking.  I figure that when overstoking, I probably have a lot of gritty unburned wood particles flying through the kiln.  With optimal stoking, I still got blackening on the front sides, but the carbon creates an inky black glaze rather than 30 grit sandpaper.  I’m completely OK with inky black glaze — it looks neat.

Inky black glaze from 11th anagama firing  View full size.

I also finally managed to mimic the surface of the floor bricks on a piece, specifically, the blue marbled glaze that forms where the floor sand melts onto the bricks.  The sand itself is inexpensive white sand that I buy at Home Depot — last time it was around $5 for 100 pounds.  The result is beautiful and the piece below is one piece I feel completely happy about.  It makes me want to get a bright light and a magnifying glass and mentally tramp through the mountainous landscape.

First, inspirational bricks:

Brick glazed by melting floor sand  View full size.

A snow capped mountain range:

Snow Capped -- anagama fired   Photogallery on this piece.

I also experimented with some local clay I was given a while back by a friend doing some construction work around his house.  The clay he gave me is everywhere around here, except it’s usually 4-6 feet down so getting it is difficult.  It is a blue-gray color in its natural state.  When I made some test pieces with it (full report here), the 100% “dug-up” clay melted into a beautiful glaze.  For this firing, I decided to try lining some of my pots with this clay.  The results were interesting.

First, the failed cup:

  View full size.

Same clay used as a liner glaze:

Dug up local clay becomes glaze   View more images here (pics 7-9) and here (pics 10-18).

Finally, I’m also very happy with my new kiln monitor setup.  I had been using the software that came with my Radio Shack Digital Mulitmeters.  It was lousy software.  Recently, QtDMM has been released for Linux and OS X.  I put together a system with an old Mini-ITX board powered by an aging VIA Nehemia 1ghz processor (think 5-6 years old).  I used Ubuntu 8.0.4 for the OS.

Kiln monitor ubuntu desktop  View full size.

The added processing power over my old system (it died between the this firing and last year’s) allowed me to set up a chimney cam — basically just an old DV camcorder connected to a firewire port.  I used Kino to display the feed.  This helped save my knees.  What I used to do is go up the steps to the mid-level, and peek at the chimney tip through a gap in the roofs covering the kiln — when I saw the flames die out, I’d run down and stoke.  Well, my knees are getting beat up by running up and down the stairs during these firings.  Now I can just stand by the kiln and watch the chimney cam.

This is what I used to see:

Old anagama chimney view  View full size.

This is what I see now:

Digital chimney view View full size.

When all is said and done, I’m totally satisfied with this firing.

PS:  if you’ve made it all the way down to the end, enjoy a sunrise:

Sunrise during the 11th anagama firing  View full size.

1 Comment »

  1. Nice work Odin, I am curious what the surrounding world looks like, around your kiln area…it’s a nice sunrise.
    And I wonder what your kiln looks like…the load in general.. I have never heard of anyone doing the temp digitally so much! awesome and it was hot.
    You use a sand to put under pots on the floor,and it melts?- I was thnking of using silica sand under some floor pieces next time.
    take care

    Comment by daniel stark — February 11, 2009 @ 9:52 pm

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