ART
For
LIVING
Lost Creek Pottery Kiln Project
As Built and First Firing Photos
After completing ceramics studies at Bradley University in spring 2004 and opening Lost Creek Pottery June 10th, I found that the biggest loss I faced was the inability to reduction fire my work. For the Past three years all the ware I had produced at Bradley was fired in one of three gas-fired reduction kilns. I had also be working at home during this time and all that work was electric fired at cone 6-10 so there was an existing vocabulary of glazes I had developed but without the ability to reduction fire some work it seemed as if half my pallet were suddenly gone. The copper reds were a thing of the past as well as Shino, Shanner Red, and all of the carefully tweaked studio standard glazes that can be found in every art show.
There simply was no choice but to buy or build my own gas fired kiln – a simple decision that opened a universe of other decisions.
Decision One: What Fuel Source?
The choices included Wood, Oil, Natural Gas or Propane.
Since I am wheelchair bound and 50 years old I was able to immediately rule out wood as a potential fuel source. Frankly I am just not physically able to fire a wood kiln on my own without spending lots of time recovering from the effort. I greatly admire the look of wood fired pottery and the look of wood fire potters – not a extra pound of flesh among all of them, all muscle and for the most part young and able bodied. There are notable exceptions but I would not be among them. No Wood-Fired pottery for me.
Oil might be a viable choice but since I have had no exposure to this fuel source I ruled it out. Just as I made this decision the hurricanes hit the oil fields and refineries in Texas and Louisiana causing great damage to the infrastructure there. Predictions now are for a 70% increase in the cost of these fuels. No Oil.
Natural Gas is the fuel that I have been firing with for the past few years and there is service available to my studio. I say it is available but it has never been routed to the building. The original heat source was Oil and we removed that during demolition. Our gas utility advised me that hooking up the building to the main would cost several thousand dollars due to the needed pipeline extension, permits, inspections, etc. Since I want to put money into the kiln and my business not into the “public” utility’s infrastructure I politely say no to Natural Gas.
This leaves the choice I have made – LP or Liquid Propane. We have a wonderfully helpful LP company in our village called “Manito Oil and Propane”. They consulted with the burner supplier (Ward Burners) in order to properly size the service to my needs and installed the properly sized tank, lines and regulator for no charge. Of course I will buy all my propane from them.
Decision Two: How big should the kiln be?
Marc Ward of Ward burners advocates building the largest kiln that you can in order to achieve economy of scale. That is, a large kiln can hold more pottery per firing and you can fire less often. For example, a kiln with 30 cubic feet of volume might require 25 gallons of propane to fire to cone ten whereas a 60 cubic kiln might require 40 gallons. Two firings of the smaller kiln would consume 50 gallons of fuel so the larger kiln might result in savings of 10 gallons of propane with each firing. There are lots of variables in these estimates but the ratios are relatively accurate.
Another joy of owning a large kiln is that when everything goes well you end up with a lot of nice pottery. The other problem with a very large kiln is that if you have a bad firing you loose a lot of production.
I am currently firing my two Skutt 1027-3 electric kilns for 3 glaze loads per week. At 6.5 cubic feet per load I find that I currently utilize 19.5 cubic feet per week for glaze firing. I know that I am not producing as much pottery as I am able due to the inability to fire all of it. After a couple weeks of high production work I found that I spent the next two weeks firing the electric kilns everyday in order to get the pottery out of the way for more work. At my best estimate I can produce 30-50% more work than I do currently if firing is not an impediment. With this established I have decided that I need a kiln with a stacking space of 29+ cubic feet.
Now that I have found the ideal volume I need to decide on the configuration of shelves and shelf sizes. The determining factor here is the size and shape of work that I produce. In my case I do make round platters that are 20-22” in diameter, so there is a need for some shelves that are 24x24”. From experience I know that I am physically able to handle 12x24” shelves although it is difficult reaching up with them. This difficulty is significant and is the determining factor in the decision to purchase some of the lighter weight nitrite bonded imported shelves as opposed to all silicon carbide shelves.
Since these large platters represent the largest pieces that I make (as far as surface area goes) I have decided on a mix of 24x24” and 12x24” shelves.
In order to arrive at the optimum kiln dimensions and shelf configurations there are certain dimensions that must be taken into account. The flame channel for each of the two power burners plus the bag wall will occupy 9” on each side of the stacking space. Requiring a total of 18” of width in addition to the stacking space. There also needs to be a certain amount of free space around the shelves in order for the kiln to arrive at temperature evenly – too tight and you will have cool zones – too loose and you waste fuel-making temperature.
Potential stacking configurations include an area that is 36x48” allowing 4 12x24” shelves and one 24x24” shelf per layer. This configuration makes for a stacking area that is 60 cubic feet. This stacking configuration would require a kiln volume of 126 cubic feet and would consume over 1,000,000 BTUs (British thermo units) or 11 gallons of propane per hour to fire. This would greatly exceed my needs and the excessive size would greatly reduce turnaround and feedback.
The best layout for my needs appears to be 2 24x24” shelf and two 12x24” shelves, for a stacking area that measures 28x54” and a chamber size of 45” wide, 45” tall and 54” deep. This allows for a stacking volume of 30 cubic feet and a total chamber volume of 63 cubic feet. A cone 10 firing will consume 600,000 BTUs and use around 7 gallons of propane per hour. Not as efficient as the 60 cubic foot kiln but more manageable for me. With the anticipated firing rate of two to three firings per month there will be enough turnaround to continue glaze development and research.
Decision Three: Up Draft, or Down Draft
This was the easiest one for me to decide, all the kilns I have ever used have been down draft. All the potters I know who fire with fuel except for three who use barrel style kilns, use down draft kilns. I will use a down draft configuration.
Decision Four: Front Loading, Top Loading, and Cart Kiln
Most of the kilns that I have experience with have been top loaders (electric) or front loaders. For a person with physical limitations either choice is problematic. In school we would fire the kiln in small groups and since I am in a wheelchair I would sit in front of the kiln and hand shelves and pottery to the more physically active (younger) who were able to climb up into the kiln. Not one time in three years did I get to actually set my own pottery on a kiln shelf. I did run the burners and monitor the kiln, log everything that happened and so on. This must change.
In order to not depend on others to load and unload my kiln I have decided that it must be a cart kiln. This will add 15-20% to the cost of the kiln but the independence will be worth the added costs.
Instead of a small concrete pad for the kiln to sit on a cart kiln requires a concrete pad big enough for the kiln and a track system. Additional concrete (5’ on each side) will be required for wheelchair access. The kiln and access areas will be covered to protect the kiln from the weather by a metal carport. Given the available metal carport sizes available a concrete pad and foundation that measures 20x18’ will be required. A cart kiln requires that the concrete pad be very flat and smooth so an experienced contractor is a must.
Decision Five: Buy or Build the Kiln
This is vary hard choice to make and there are several variables that must be understood and analyzed before the proper decision can be made. The first thing I had to research was the availability of commercially manufactured kilns that would meet my needs. In a very short time I found several that could meet most every need I had, but there were compromises that would have to be accepted in every case. I had the good fortune to attend the 2005 NCECA conference in Baltimore this year and to meet several Kiln builders and look at their products. While all of them made fine products and were very helpful, I felt that I could build a suitable kiln for much less cost in dollars. There is no free lunch and there are no cheaper ways to build a good quality kiln. My choice was to pay for the construction in “sweat-equity” dollars and use the hard currency for better materials.
Most of the Kilns I looked at were single brick wall thickness, some had backup insulation but some did not. Several had power burners but not the configuration I wanted. It seemed that there were always some area where cost cutting shortcuts were taken in production that I was uncomfortable with.
Having examined the available sources I next needed to look at my abilities to decide if I had the right stuff to tackle building my kiln from scratch. In my case I am an experienced welder and machinist with 25+ years experience, I also spent a number of years working with gas burners and heating systems so plumbing and gas components are familiar ground. Although I have never built a kiln I decide that I would be able to cross any hurtles that this project puts in my way.
I do not feel that a person wanting to build a kiln needs my years of experience in order to safely build a kiln – the most important thing you must know is your abilities and know when you are exceeding them. Do not be afraid to hire a contractor to do your welding for you or to do the concrete work if that is beyond your abilities. You must decide how much work you can do and how much work you are will to hire others to do for you.
If you decide that you will have to hire more work done than you are willing to do yourself then buy the kiln from one of the many reputable builders that advertise each month in the magazines we all get. It will arrive on a truck ready to hook up and fire – can’t get easier than that. If you are like me and like a challenge and prefer to have things your own way – Build It Yourself!
Over
the next few months I will build the kiln
that I have outlined here. Check back as we
work to put ideas and design on paper and then
into real brick and steel!