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Nataniajoy24

Help with using a Duncan Automatic Teacher-Plus Kiln

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Hello folks! I received a Duncan kiln from a family member about 7 years ago and was never taught how to use it. I attempted to figure it out on my own, but gave up because I was having too much trouble with it. I have never operated a kiln on my own- only seen electric kilns in use. 

Has anyone operated this particular kiln (DA820-2), and if so, could you answer a few questions for me?

  • I believe I was having trouble because I did not have any pyrometric cone/bar things to turn off the kiln when it reached the right temp (clearly I'm a newbie). In the manual I have for my kiln, it says I need 'ASD' cones.  If my kiln fires to Cone 8, which cone of pyrometric bars do I need ? Does it always depend on the clay's cone?
  • Where do I place these ^ cones when I have them? Is there a hole in the bars that slides onto the knob on the inside of the kiln wall?
  • Do I need to have witness cones + the ASD cones? 
  • After each firing, do I need to have new witness cones? 

Thank you!!

Natania 

 

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IMG_3446.jpg

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You need small cones or bars, for whatever cone you're firing to. Most folks bisque to cone 04, then you'll glaze to whatever cone your clay matures at. Your clay and glaze should mature at the same temp. In electric kilns, that generally means either cone 04/05 or cone 5/6. To use the cone, lift the weight on the sitter, push down the claw that holds the weight, then place the cone inside the kiln on the two bars in the sitter, with the rod sitting on top of the cone. That rod is connected to the claw on the outside. When the cone bends, the rod goes down, the claw goes up and releases the weight which hits the switch that shuts off the kiln. Have the number on the cone face toward the inside of the kiln, so you can see it. The timer on the sitter should be set to about 20 minutes longer than the firing is expected to take. It is just a countdown timer, it does not control how long the firing takes. So you'll need to do a bisque and glaze firing to figure out how long the firing will take and set the time accordingly. For the first firing just set it to 12 hours and do the math afterwards. You need a new cone for every firing. Witness cones are not necessary once you have the sitter calibrated. You may want to use them for the first couple of firings to make sure everything is good.

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Okay, thank you! Do I need to warm up the kiln before using it or do I load it and do the process you explained and then prop open the lid after the kiln shuts off? On some older kilns, I’ve found (from YouTube videos) that the people slightly prop open the kiln and set it on low for several hours with the peepholes open. Any advice for this part? 

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If the kiln doesn't have a downdraft vent attached, keep the top peep open throughout the firing. You really don't need to prop the lid. Make sure everything is dry before firing. No need to warm up the kiln before loading. Keep the lid closed after firing until it's cooled down below 250F.

If you have a teacher that would let you help load and fire his/her kiln a couple times that would be good.

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8 hours ago, Nataniajoy24 said:

pyrometric cone/bar things to turn off the kiln when it reached the right temp (clearly I'm a newbie). In the manual I have for my kiln, it says I need 'ASD' cones.

basically what you do is buy cones for different temps you might be firing to, and see which ones are melting while looking through the vent holes of your kiln. You'll need something to look through like welding glass or special glasses or you'll burn your retinas. If your kiln says cone 8 (mine does) it probably means it will technically fire around cone 8 but you'll get a lot more life out of the elements if you keep it around cone 6. Mine says cone 8-10 but since there are a ton of beautiful glazes and clays for 5-6 that's what I'm going with, and I'll save some money in the long run. Don't prop your kiln open just leave a kiln plug out through the whole firing like Neil said. 

8 hours ago, Nataniajoy24 said:

Where do I place these ^ cones when I have them? Is there a hole in the bars that slides onto the knob on the inside of the kiln wall?

just to be clear the cone does not shut off the mechanism, you'll just be checking it through a kiln plug hole and when the one that's the temp you want has melted, then the kiln has reached the temp you want it to get to. Place the cones where they can be seen thusly. To be honest I'm new to kilns and I don't know what your kiln means by "Automatic" since it looks like a manual kiln from the images. This means you have to watch the temperature and turn it off yourself. There is a thing called a "setter" involved in the process but someone else will have to pick up the thread because I don't know from manual kilns. I wouldn't fire it until you figure out how to shut it off. 

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nataniajoy,  you are very fortunate to have such a nice manual kiln as a gift.  i thought by now you would have received an answer that addresses your problem as a totally new kiln user.

couple of things might help you understand the manual fred has so helpfully found for you.  you need to realize that the kiln is a very old one as far as its manufacturing date is concerned and there was a slightly different vocabulary used then.  "Automatic"  back then meant your kiln was equipped with a Kiln Sitter that would mechanically turn off the kiln when a particular temperature was reached.  the manual keeps referring to it as the ASD, automatic shutoff device (or sitter. prior to the use of a sitter, the potter had to watch the firing and turn it off at the end by looking into the kiln peep holes and judging the temperature at which to turn off the electricity. ) cones have been use for over a hundred years to help do that.

the temperature you select for each firing is commonly referred to by a cone number.   that means the same kiln can be used by potters who fire earthenware or stoneware which is usually fired to a higher temperature.  so you need to select the cone number for the clay and/or glazes you are using.

the number on the cone indicates a temperature but the firing can take a little longer as the elements wear out over time.  so the cone ,which you place HORIZONTALLY across the two little arms, will determine the time and temperature of your firing.  the arms hold up the cone and the rod end of the "claw" of the sitter sits over the cone resting on it.   SINCE THE INVENTION OF CONE BARS MANY PEOPLE USE THEM IN THE SITTER.  bars are of a uniform size end to end.  cones are tapered and some people have trouble putting them onto the arms and getting the claw rod in the middle of the cone.

when the cone gets hot enough for a long enough time, it will melt.  that means it sinks down and allows the rod end of the claw to sink as well.  the other end of the claw, the part outside the kiln, is really the claw looking end and it is holding a weight that will be released by the rising of the claw.  the weight will snap down and activate a round electrical shut off button that is located on the outside of the sitter.   (if you find you cannot start your kiln at any time, check that the claw is holding the weight and the button is close to the kiln, not sticking out.) 

i hope this is enough to help you read the manual and that will explain your particular kiln.  

the most important thing you need to learn is that it is CRITICALLY IMPORTANT that you understand the cone numbers of your clay and glazes.  look at a CONE CHART and read the numbers and the temperatures carefully.   there are some essential facts that are commonly glossed over when experienced potters are talking to each other.   

09 08 07 06 05 04 03 02 01 AND THEN CONE 1 2 3 4 5 6 7 8 9 10 ETC.  are each a little hotter running from left to right.  check the chart!  and check your clay.  write the cone # on the bag of clay so you  DO NOT make the mistake of thinking that cone 6 is the same as cone 06.  that is a completely different temperature and if you use cone 06 clay and use a #6 cone in your sitter, you will probably melt everything and ruin the kiln.

see the recent post by benzine for what can happen.

hope you bothered to read this long post and understand it.

 

 

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