Thursday, December 10, 2009

The pressure is on!

Middle Tennessee Gas Company came out in the rain and put pressure gauges into the system at several places. One before the regulator, one after the regulator before the meter, one right after the meter and another where the line change to 1/2 inch piping. Now with the two gages I have at the burners, that makes 6 gages in total. What fun for an engineer!

Took just a minute of running the system to determine that the orifice in the regulator was too small. It took just another minute for them to replace it. The pressure at the burners is where it was designed for.

Now, it is time to make some ware and see if it will reach temperature. [It also has to get warm enough so all my clay isn't frozen solid]

Wednesday, December 02, 2009

Close, but no cigar

The gas company's contractor and installed the new flow suppression device. I was banging away on my computer when I heard the backhoe.

The device is really nothing more than a spring and a ball. In the small one that was in there, you can blow into the end and make it close.

The scale of the photos distorts the difference in size. The new one is about 4 times as large. You can blow yourself blue; you won't get this one to close.

I was curious about how they connect the pipe. It is welded using "irons" that they heat to about 450 degrees.

They have mechanical guides the bring the pipe together once they apply the heat to it. Makes sense, just never seen it done before.

The whole process of changing out the device took less than an hour.

After they had the new device installed, I fired up the burners for another test. No shut down, but it still is not developing they pressure I want. My guess is that we have the kiln piping undersized and are not getting the flow needed. The gas company is coming out next week with pressure gages and we are going to troubleshoot the system. I think I will run some numbers and give Ward Burners a call.

Tuesday, December 01, 2009

That's why you do tests

Been off on a trip to Florida to help my daughter move and attend a family Thanksgiving reunion. It was fun, but now its back to kilns and pots. I was inspired by a stop to the Clay & Paper gallery in Dunedin, FL. I got to see a number of potter's work including McKenzie Smith's. I took a workshop of his acouple of years ago and I really enjoy both him and his ware.

The test went well up to the point where I tried turned the burners up to full operating pressure. I turned up one burner and was only able to get 5 psi. I tried to turn the other up and the pressure on the whole system dropped to less than 0.5 psi. I shut the system in and went away for about 30 minutes and then tried relighting pilots and burners. They worked as before the drop. I slowly turned both burners up and when I got to 4.0 psi on both burners, it shut in again. Had to be a safety device on the line. I checked with the engineer at the gas company and he said it could be the regulator or a federally mandated flow suppression device that was under sized. They are due here in a little while to dig up the line at the connection to the town supply main to replace the flow suppression device with a larger one. Then they want to run the burners at maximum pressure to verify that was it. I am warming the kiln just because I am a little nervous about throwing that much heat at a cold kiln.

Hopefully, this will get me my 6 psi design operating pressure.

Saturday, November 14, 2009

Kiln done, commisioning underway!

I lit the remora burners (pilots) this morning and the kiln is drying out. I am holding it at about 225 degrees for a few hours. Then I am going to ease it up to red heat to get a feel for it. Then, I really need to start making pots.

One of the last tasks was to put a "wash" on the hard brick to help them withstand the effects of the soda/salt. The product I am using was recommended by Larkin Refractory Solutions. It is a high alumina refractory plastic (Econoram 90 TR by Pryor Giggey Co.)

I also added the IFB floor to the firebox and floor flue. The IFB was dipped in the Econoram wash before placing. Hopefully, these will help protect the hard brick in these high heat, corrosive areas. I had a couple of Super Duty hard bricks to use as target bricks.

I cut 9" sections of a kiln shelf to use as the interior flue roof. When I am using soda/salt I will use coils of wadding to keep these from glazing to the floor.

This is how the shelves layout. As you can see the hot gases are forced to the center under the set to leave the kiln. Hopefully, this will give uniformity in heat top to bottom, front to back.

When I start up this morning, I used a weed burner through the passive damper hole to heat the chimney and start the draw. I don't think this is going to be necessary except in really cold weather and maybe not even then.

Well , the first step in making pots is cleaning up the studio. It has really gotten trashed the last couple of weeks.

Wednesday, November 11, 2009

Topping out!

When they finish the framing of a tall building they "top" it by erecting a Christmas tree on the highest steel. I didn't feel the Christmas tree thing, but thought a salt/ash glazed jug might do the job. The kiln is about 99% done.

Here are some pictures of the cutting through the roof and flashing out the opening.

I didn't quite get it. One side held water out fine, but the other leaked badly.

Looking at it, I can see where the caulking needs to go. I am thinking of using a "tar" to fill the pools that form up slope from the chimney. The other option is to fabricate some metal flashing to do the same thing. As I don't have metal forming tools this might be a little challenging.

I also had a problem with some of the silcon caulk I used. It didn't set and washed out in the rain. I wiped it off and will replace it with a better brand of caulk.

I have all my shelves loaded into the kiln to dry out in a test firing. They had been kept in a wood box under tarps, but moisture got in. It seem to cause the coating that the shelves are covered with when shipped into an acid which etched itself into the shelf. Below is a picture of the most damaged. Not the best.

I will cut the bricks for the door and then slowly get it hot!

Friday, November 06, 2009

I've got gas!

Middle Tennessee Natural Gas came, set the meter and hooked the piping. I decided to have them do the plumbing. They have the tools, the materials, etc. and it seemed to make them more comfortable. As the kiln operates at a pressure way above normal house pressure, they raised an eye brow or two when I started talking to them about the kiln. They did a good job and I have to admit I would have taken far, far longer to do it. I have even lit the burners - sweet.

Here are a few shots of the arch construction. I changed the design a bit. I had enough "extra" IFB to add a layer. So the make up is, hard brick arch, two layers of kaowool, a layer of IFB, another layer of kaowool, chicken wire and finally a covering of Insulating castable. Hopefully that will keep the heat in.

I cut the hole through the roof yesterday and flashed it. Today, it is time to stack chimney brick.

Thursday, November 05, 2009

Fuzzy Bricks

When I went out to the kiln to work the other day, I found fuzzy bricks on the chimney!

I suspected that it had something to do with moisture and sodium silicate, but I called Jim and Pam down at Larkin to make sure - they said don't panic, just shave them and go on. They confirmed my suspicions. Now how do you shave a brick? Does Gillette have a special blade for that?

Friday, October 30, 2009

It may be Fall, but its Sprung!

The last couple of days have been long anticipated. The burner supports were fabricated by my friend Steve and I installed them. The burners are waiting now for Middle Tennessee Natural Gas to come set the meter and pipe them. The engineer called to size the meter, so I know I am in the queue.

After all the worrying, fussing and general just plain thinking about it, it took less than two hours to set the support form, add the bricks and then remove the support.

So here is the arch in-place.

If I am not careful, I might actually have a kiln soon and get back to making pots instead of kilns.

Tuesday, October 27, 2009

Don't pay the ransom!

I have escaped from the kidnappers! Okay, maybe I wasn't kidnapped. I just haven't been posting.

First, congratulations to "Hoosier Mama" and her first firing of her new salt kiln. It was also her first firing of a gas kiln! Way to go - be sure to check out her blog Hoosier Mama Now to see her results

Despite the lack of posts, progress is being made and I am getting a hazy view of the end. I completed the arch support and my friend Steve took my drawings and fabricated the kiln's steel work.

The arch support is rather simple construction, just some OSB and 2x4 cross members.

I found some fiberboard at Loews that was $7 for a 4'x8' sheet.

I clamped it on, traced the shape and cut it with my trusty jig saw.

This is the finished support ready to put in the kiln.

Here is the steel work fitted onto the kiln.

This is an outside view of the arch constraints.

And here is an end view of the skew bricks, the backing bricks and the steel constraints.

Steve also did a great job of fabricating the burner supports. I will install these and post pictures as soon as its stops raining.

Saturday, October 10, 2009

Passive Damper and Arch Support

This week has slipped by and it seems like I have been a slacker. I guess I am slowing down as I approach the 60 years on this planet milestone. It may be just the age or it may be that the city frenzies are fading into the past. I did get a bunch of bowls glazed and fired for the Cookeville Cooking on the Square event. This benefits Habitat for Humanity. Below are the hand built bowls that I whined about not caring for earlier. I still am not fond of them, but the glazing almost saved them. They were fired in oxidation to cone 7 with a Mid-South Opulence glaze called antique iron.

I have brought the chimney up and constructed the passive damper. This is basically a hole to open to decrease the "draw" up the chimney. It is used to make small adjustments as compared to the active damper. The next task on the stack is to cut a hole in the roof and continue up to its full height.

I started the arch support for springing the arch into place. Below you can see it laid out on OSB.

I traced the curve onto the OSB and then used a compass to offset the curve by the thickness of the plywood that I will use to cover the support.

Here are the support ends cut out by my trusty-rusty Sears jig saw. This was my father's. He had it a few years and I have had it about 20 years. Still going strong (but I have my eye on a DeWalt 18v cordless).

Steve, who is going to do the metal work for me, called and if things go as planned, that should get done next weekend.

Friday, October 02, 2009

Active Damper

I built the damper yesterday. After a lot of back and forth in my mind about how to do it, I settled on slicing the brick lengthwise and using a piece of angle iron. The pictures pretty much tell the story.

I am using Alsey Motar on the chimney to better seal it and hopeful promote a good draw. I will go another few layers with the high duty bricks and then change over to the medium duty to complete. I also intend to add at least one passive damper.

Friday, September 25, 2009


Layer 18 is in and it is time for the arch once I get the metal work fabricated and installed. I also need to make an arch support. But this is a milestone.

I was pleased that the tops of the skew bricks are level and even.

The plane of layer 18 seems to be within 1/8 inch, which also pleases me. Of course, this will all change when the bricks start moving around during firing, but it is a good start.

Tuesday, September 22, 2009

Back to work

I finally gave up waiting on the rain and started working on the kiln between showers. Row 14 is done leaving only 4 more rows to go before the arch goes in. I am going to do some electric kiln testing today, with some test tiles thrown in, but should be able to dodge the showers and get a layer or two more completed. I have a friend who is going to do the metal work for me. I need to get him a material list so he can order the angle iron and square tubing. I briefly thought about buying a welding machine and learning how to weld, but my mother's voice still rings in my ears about risking my one good eye (I lost an eye to an accident when I was about 3 years old).

After several years I finally got around to trying Wes Smith's suggestion of "marks of addition". He noted during a critique, that my work was all "marks of subtraction". He was right - but it takes me a while to get around to things (just ask my wife, Elise). Here is the vase I was coil-throwing. It is about 23 inches tall. The medallions and dragons are from a sprig mold that I bought.

Here is a shot of the sprigs.

Not all experiments are successful. These are the extruded hand built bowls that I was working on. I am not happy with the results, but will fire them and glazed them for the Habitat for Humanity Bowlathon in Cookeville. They may be bad bowls, but they will help in a good cause.

As you can see, I have been playing around with the HTML and CSS. I still need to fuss some more, so expect things to change a bit more - when I get around to it.