Vapor

the Altar

We were firing the last salt kiln of the year and had vapor everywhere on campus (a heavy humid day). The inside of the empty anagama was foggy...

What we did

The PrattMWP anagama

The firing went very well until the end. Before getting into the schedule a few notes are needed. More images will be posted soon...

1) We changed the door configuration. All ports were brought up one course. We (I) thought this might help with keeping coals in the firebox while letting more primary air in over the coals. The secondary air ports were move up as was the stoking port. These changes proved to be a problem in hindsight. It created a jet stream through the chamber making damper management more difficult and heat distribution erratic. At least that is my thinking.

2) The ware load was not suited to the chamber. Too much flatware with not enough volumetric ware to baffle the flame. 

So, to condense the schedule (Our pyrometer is in the rear of the chamber; the cones in the rear are 8,9,10, while in the front we use 8,9,10,11,12. We have easily reached ∆ 12 in the front in past firings.)-

Start up: 6:30 pm (Thursday April 26)

Our intent was to go up very slow. We had a piece in the front that was tall and did not want to risk it. 10 to 15 degrees every half hour. We (Amber and Eric) stoked lightly through the night to hit our morning temperature goal of 500˚ F.

From that point we kept the ramp the same, keeping the damper 3/4 open for the duration. By midnight Saturday (April 27) we were at 1500˚ F. 

My take on a long firing is simple- get it up to temperature and then soak for as long as personal energy and fuel allow.  Here we took too much time at the front end to protect the ware.  It is in some ways a waste of fuel. But the up side is that my sophomores got some experience in careful, attentive stoking, a process they will surely remember for future firings. 

We hit 2000˚ at 10:30 am on Saturday. Our ramp was fairly consistent for the rest of the firing.

At 4:00 pm Saturday we had ∆ 8 soft in the rear and ∆ 10 down in the front.  Then came the big stall. No matter what we could not push heat to the rear. We had the usual positive cues such as good heat in the firebox as indicated by lots of blue flame off the coals and white heat just above the coals, but we began to notice the flame as flat and streaking through the chamber.  Also, we noticed a lot of unburned fuel or carbon at the crown of the firebox and into the upper ware chamber.

Previous door setup.

I think the problem was the raised door ports. We were getting less chamber time from the flame, a jet stream in a sense, with the unburned fuel causing the stall. We had created zones in the firing chamber. I can't be sure, but when trying to dampen the kiln, we could not get the right fuel to air ratio, or I should say, get the flame to work around the chamber, not through it. Lots of smoke under the shed, but little to show for it in the kiln.

Door and stoking port block.

Exhausted, we called it quits around 5:30 pm Saturday (April 28). Although we got some great pots from the kiln, learning to fire this baby is a work in progress. 

As I said before, I have made some changes to the kiln floor and stacking scheme. I will certainly go back to the door pattern we used earlier. The changes and strategy will be discussed next post.

Wood fired by Bryan McGrath

Anagama 2012

Old kiln yard MWPAI

New kiln yard PrattMWP

We finally fired the anagama after a week delay due to my lack of organizing energy. The firing was a long one, too long for my liking, a sure sign of age. We started on Thursday evening with Amber and Eric (sophomores in my intro Ceramics Sculpture class- the best I have ever had!) taking the night shift. They are quick studies and hit the target temperatures beautifully.  By morning the kiln was ready for the next shift. The firing proceeded through the next 36 hours, firing off Saturday evening. Although the students thought it was a good firing I have different thoughts and will toss them about in the next post.

As a result of the firing, I made some changes to the kiln floor and the stacking scheme for the next firing. My reasoning will be laid out as well.

I just read a piece from the NCECA conference, a panel discussion on soda firing. I am amazed at the differing approaches and technical knowledge sited for various results. Any technical information stated is always helpful. No matter how experienced a potter it is always good to hear this information from others to compare and contrast notions. It would take far too many lifetimes to acquire true expertise alone. Ceramics is too broad and deep a medium.

But the information can sometimes, at quick glance, seem contradictory. The reason lies in the many, many variables found in each technique or process; variables that are too often, for brevity, left out, something of which we all need to be mindful.

Any technique passed on to another is just show and tell, regardless of who is showing and telling. All techniques need to be understood intrinsically, and as a result, applicable under various conditions. One needs to understand process in a broad manner. Firing a kiln is the best example. Simple put, all techniques need to become yours, no matter how traditional or modern they appear. This takes time and attention. In the end, the technique will become yours for your needs and materials. That is the goal.

Spring 2012 Anagama Firing

Soy bottle and tray; wood fired by Bryan McGrath

We are planning the spring wood firing for the week of April 16th. We will prep and load the 17th - 19th and begin the firing sometime on the 19th. We are looking for a good 48 hour firing (+ or -) to be fired off on the evening of the 21st. It will be a combination of sophomore work (sculpture/design class) and continuing education student work.

Our anagama is one of only four operating wood burning kilns in central New York State. There may be a total of 12 in the entire state, so we are in exclusive company. Our design is unique for its hidden chamber between the main chamber and the stack. We are planning to experiment with a mid temperature clay in that chamber with the possible addition of some salt.

No, this image isn't from this winter!

If you are in the area the best day to stop by is the evening of April 21st as we fire the kiln off.  Quite a site!