neilestrick

I've never had that problem, even with the really thick CoreLites, but I can totally see how it may be an issue.

I've done the math on the cost of Thermal-Lite and CoreLite shelves for my 28" wide kiln, and it will take almost 875 firings before I break even with the more expensive shelves, and that's with buying two sets of the CoreLite because they won't last as long. Because I would only save 1 7/8" of height per firing in a glaze firing with the thinner shelves, and half that in a bisque, it's like getting a free firing every 19 loads. That averages out to $1.11 savings per load, which isn't much. This is also assuming I never accidentally break any of the Thermal-Lite shelves, and that I actually fire the kiln 876 times over the life of the shelves. For me that's not a problem, but for the average hobbyist who does 2 firings a month, that means it'll take 36 years for the more expensive shelves to pay off. However, for a production potter the extra 2 inches of space means 5% fewer kiln loads, which can really add up if you're firing a lot. And if you have a larger kiln than a typical 27" tall electric kiln, like a large gas kiln, then the payoff will come much faster. As for the weight of the more expensive shelves being so much better, they're really not. The 26" half round Thermal-Lite and CoreLite I used in my calculations have a weight difference of only 1 pound, so it's really not enough to make a significant difference in wear and tear on your body or the cost of firing.

I just made my morning tea- porcelain mug with water in it, microwaved for 2 minutes. The water is too hot to drink, but the mug handle is very cool, like maybe 85 degrees instead of room temp. I'm going to call that microwave safe.

The chain won't short out a thermocouple connection permanently, it'll just make it read funny while it's touching. Double check your thermocouple connections at both the thermocouple end and the controller end. Make sure the +/- wires are in the correct positions. On type K thermocouples, yellow is positive, red it negative. Maker sure the thermocouple isn't too close to the metal casing on the kiln.

These pieces were all dry, right out of the cabinet.

The kiln needs air flow under it so you don't overheat the floor, and the bottom of the kiln should be at least as far from the floor as the stand makes it, usually about 8 inches. Cinder blocks work, but you have to orient them so the holes are facing horizontal, so air can flow through them. Or you can put a sturdy piece of sheet metal under the kiln, on the stand, to support the crumbling bricks.

I just ran a 1 minute microwave test with 4 pots with the following clay bodies: Standard 365 cone 6 English porcelain Standard 266 black clay A medium-brown cone 10 stoneware with grog A red body, fired around cone 3. After microwaving for 1 minute and measuring the temperature of the piece in the middle, using a laser pyrometer: The porcelain and the cone 10 body both came out around 140F. Kinda hot, but I could get them out of the microwave. The 266 black hit 170F, too hot to handle. The red body was over 220F. Here's the really interesting thing, though: in all cases, the unglazed areas were a lot hotter than the glazed areas. When I measured down the side of the piece, they were all cooler at the top than they were at the bottom, presumably because they all have unglazed bottoms. The red clay pot was glazed on the inside and about 3/4 of the way down on the outside, and at the very bottom of the outside where it was unglazed, it measured over 260F. In all cases, the bottom inside was at least 30 degrees hotter than further up the walls. So glaze on both sides seems to have a pretty big effect on how hot the pot gets. @Kelly in AK if that plate was glazed on the bottom like most commercial plates are, that may explain why it stayed cool in the microwave. Another odd thing: If I microwaved several at a time, they didn't get as hot- just like when you have more food in the microwave you have to run it longer. But the unglazed areas heated up almost as much as when I ran them alone. Strange stuff. So iron in the body, glaze, vitrification? I don't know if the red body got hotter because of the iron in it or because it's not fully vitrified, or both? The Standard 266 has a lot of iron, maybe more than the red body, but it's more vitrified than the red, so is that why it didn't get as hot? Or did the red get hotter because it has more unglazed area? Lots of mysteries here. Having something in the pot that has to get heated up definitely slows down the heating of the pot. I microwave a mug of water 3-4 times a week in my studio for tea. It's made of Standard 365 cone 6 English porcelain, and every day I pull it out of the microwave by the handle with no problem.

10 would be the most I would try to center on it. I've done that. It can do it, but it would prefer smaller amounts. Also bear in mind that the wheel is fairly lightweight, so it's easy to slide it around when centering that much clay. You have to have it up against something solid in order to keep it from moving.

Post some pictures of the element connections and the inside of the control box so we can see the relays.

If that is indeed the same kiln, then at 7.5 cubic feet and 45 amps, it may very well get to cone 9, maybe 10. If it's in good condition and the price is right, it could be a good purchase.

It doesn't matter.

@chloemmetcalf What are the dimensions of the kiln interior. If we know the volume of the kiln we can compare that and the wattage to other kilns of similar size to get an idea of how hot it will get.

Kilns rated to 2300F are cone 8 kilns. It'll get you to cone 6, but your element life will not be as good as a cone 10 kiln. You'll likely get 70-80 firings from a set of elements instead of 130-150. The elements just can't wear as much before they're too worn to do the job. If you're only doing a bisque and glaze once a month that's probably not a big deal. If you're firing weekly, the added cost of elements will add up quickly. Also, look up what new elements for the kiln will cost. The price can vary greatly among Paragon kilns.

The problem for me is when mixing chrome-tin pinks for my students. I have 7 and 10 gallon buckets in my studio, which means anywhere from 1.3-2 pounds per bucket and that gets expensive pretty fast even with just two colors. If it was just for me I wouldn't care at all. It would take a lot for me to consider a glaze to be too expensive for my own work.

The posts must align vertically all the way from the top of the kiln to the floor. The shelf may warp or crack if a post is sitting on the shelf but is not supported in the same spot below the shelf. You can usually get away with it if there's only one shelf above, or if you're putting in a quarter shelf, but I would not expect a shelf at the very bottom to carry the weight of multiple shelves above it without a post aligning underneath. You can't tripod the full shelf and then have 4 posts sitting on top of it, because only 1 post would align and the unsupported areas would carry most of the weight.