Electric kiln- L&L JD230

With the help of the L&L technician over the phone, he concluded that my L&L JD230 kiln is fine after the following tests, and the problem was due to the shelf touching the pyrometer.  I will retry the bisque tomorrow.

Here is two tests to check the elements and the replays on the kiln.

First, the elements.  Unplug the cord connecting to the red box from the elements. Check the ohms by inserting the probes of the digital multimeter into each hole of the flat part of the plug tightly.  Mine read around 17 ohm, for each plug.  If element is broken, it does not register the resistance. I bought this kiln with the heavy duty elements option in 2001, and used for bisque cone 07 only.  I bisque roughly 40-50 times a year. So, this have been 400 bisque firing done.  According to the technician, my element will be for good for long time.



Second, relays. Turn on the power, and set the kiln to "fast glaze"mode, and turn on.  Unplug the same plug, and insert the plug into the socket this time, and read the voltage.  I read 235V.  This shows the relay is working fine.  My friend told me that I can get the relays at the Grainger at reasonable price.



There is very good instruction/ trouble shoot articles available at the L&L website.

Three in row

I fired the kiln  on Friday. Another good one. The following picture proves the reason why I was seeking the good firing. They are from three firings. Last year, I was losing 6 to 10 pieces per kiln.  Do the mass. I gained almost 30 pieces.  My friend potter in Japan told me long time ago that the yield should be 95 % to be the production potter. It is very hard figure, but this has been my goal, anyway.



One problem is solved, then another pops up.  My electric kiln showed "ERRD" sign today, and could not complete the bisque firing.  I need to wait the kiln cool-off to see the element problem or something else.  I talked with L&L technician, and he told me he thinks either the element or the relay. This kiln has been problem free for almost ten years.  I replaced the thermocouples two year ago.   I have no complain, and bought the elements last year expecting to fail.

Peregrine falcon

I read an interesting article about the falcons in Rochester on Sunday.  Mariah, a star of the web-cam, placed in the mannmade nesting box at the Kodak tower several years ago, lost the Territorial battle with new comer, Bonnie and Clyde.

Today, I looked up at roof top of the studio, there  is a falcon standing the edge of the roof.  I saw the falcon -like bird chasing the dove the other day.  We have lots of doves on the roof of the building as plenty of grain dropped from the freight cars at the yard.



Pots are all waxed, but I am waiting the snow storm (wind) to settle down a bit.  We had more than foot of heavy back-breaking snow over the weekend. I threw berry bowls instead of glazing today.

Two in row

I opened the kiln today. Very good reduction again. I got one mugs got too much reduction.  Just before the body reduction, the wind picked up a bit, and felt some downdraft for while.  Once the gas pressure was up, I did not see much of problem.  I repeated the same firing, so the gas pressure was the answer I have been looking for. I think I will try to open up a blower flap (secondary air) next firing to see any difference to the reduction. It is very nice feeling to have no seconds again.  Pottery is not like the painting, and you really cannot (draw over) refire the piece to satisfaction. You will find out the result 24 hours after the firing. Yes, I have some vision of the finished piece when glazing, and try to apply glazes, sometime a bit thicker, double dipping, etc imaging the flow of the glaze when it started to melt in the kiln.  Firing, they’re so many variables, weather, how you load the kiln, etc. We are very superstitious. In Japan, the female was not used to allow to the kiln room as they afraid of the fire god being jealous, and messing up the firing. I don't believe that, of course.  I sometime wish I can see the progress of the firing in real time, like painting. On the other hand, firing is the important part of craft, and what makes the pottery.

Kiln is loaded

I have been busy throwing mugs,bowls.... I am about running out the space.  I will fire them next two weeks.  Kiln is loaded today. I am kind of nervous for tomorrow's firing.  I hope to repeat the same firing tomorrow.

Our dog is being himself.

Dog and bone

We tend to give some table scrap to our 4lb yorkie. Last night, we gave a piece from a rack of lamb, about 2 inch. He usually play with it. But he swallowed it as we watched.  I thought it was too big to swallow. Then reality set in. My wife said to google.  So I did. Most searches came up, take to vet immediately,X-ray, surgery..... We panicked. I called my friend sculpture, who works at the vet.  She said there is nothing we can do expect to wait for 24 to 48 hours, and check the stool. She also suggested to give him a large portion of meal, 1/3 chicken and 2/3 cooked rice to coat (wrap) the bone inside the intestine.  Try to vomit to retrieve is not good idea. If he has problem going to bath room, then, we need to bring in to the vet.  We calmed down a bit, but feeling so bad to feed the table scrap. Not mention the medical bill in the future.

In our surprise, we found the bone in his bathroom this morning.  He somehow vomited it last night when he ate dry food. He is fine, running around today.  I will never give him anymore bones. I learned my lesson.

No seconds!!

I unloaded the kiln today.  Near perfect firing.  I fired on Saturday when the wind finally calmed down. It was very bad firing from the beginning, similar to the last firing. I decided to move around the oxyprobe to see what going on.



I could not get good reduction reading with the oxyprobe next chimney while it read heavy reduction at spy holes.  I could not reduce the chimney side of the kiln by changing damper or blower setting at all. I re-read Nils Lou's Art of firing while the kiln was acting strange. The book explain the importance of the tuberance. Then I thought, blower does not do anything. Then what.... Gas pressure!

I was hesitance to raise the gas pressure, first 3.5 PSI, which I have never done before, it did not change the reading that much, but when raise to 4 PSI, it changed the atmosphere of the kiln dramatically. I started seeing the reading evened out at three locations at 600-620 as I opened the damper accordingly. I have never had this much gas pressure available before the move (I knew this time have up to 7PSI), but never think to use that much since the kiln was firing fine with below 3.3 PSI for 15 years.  I was the same building across the hall from the current studio 15 years ago for two years.

All the things I have tried last three years, but the gas pressure. I actually lowered the pressure I was using because the glaze defect I thought was due to the rapid raise or to hot as it happened where the flame hit directly.  Now I think, I got the heavy reduction near the door, and which was causing the glaze to react strangely, not heat.  I do not have enough pull at the chimney, so it reduced heavily before the exit flue. I needed the push by the gas pressure.  I thought opposite, I had too much updraft (14' of chimney) and getting the oxidation. I was wrong.  I am looking forward the next firing.  I think I have solve the problem.