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About curt

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  1. I would be looking at the calcium borate frit. What chemistry? Could be a low melter making trouble with the other glaze ingredients...
  2. If you are recycling clay it could be contaminants getting picked up in your clay body from somewhere in your process, which may explain why some pots have it and some pots don’t. Have you tried firing with brand new clay right out of the bag. Not thrown, not even wedged, just straight out of the bag and in to the kiln?
  3. Also, you may want to get their specification of “dust” before loading up the trailer. My experience is that what you and I call dust may not be what they call dust...
  4. Agree it looks underfired just from the picture. That satiny-matte-like finish with a surface that is not quite smooth looks like other underfired work I have seen. Also the opaqueish whiteness (as opposed to transparency/clearness) suggests that there are underfired ingredients in the glaze which have not combined in to the melt. also, eyeballing the ratio of outright silica to alumina in this glaze - before even including the kaolin - already firmly suggests matte glaze to me. Add in the kaolin and it would be even more matte I think. Perhaps the stains were meant to add some (a lo
  5. Yes now that is a cooling dunt. Very sharp edged, sharp enough to cut you if you run your finger over it with a bit of pressure. The earlier crack does not have anything like this. The glaze knew the crack was there from the very beginning and simply pulled away from it throughout the firing, just like it was pulling away from ridges elsewhere on the pot (since it is pretty clearly a breaking glaze).
  6. What Neil said. Glaze pulled away from crack just like where it breaks elsewhere on the pot says this crack was there pre-glaze-firing. Likely from Bisque either fired too soft or Bisque cooled too quick, or both. Have seen similar cracks in our studio. Or as Neil suggests possibly there from drying stress for the types of reasons Babs quoted above.
  7. I got a brand new Shimpo VL Whisper from the US a couple years ago, and directly on the circuitboard there is an option to change voltage from 110 to 240 by unsoldering a connection and resoldering it into another connection nearby. Then you don’t need a voltage adapter of your own. I did this and it worked fine. Just need the physical plug adapter, but make sure it is grounded! For a while mine was not and I can tell you that is not good. Shimpo had instructions on how to do the soldering change which were able to be downloaded from their website if I recall. Not sure if your whe
  8. No foot at all really, Babs. The outside line of the pot was just straight down the wall (right past the level of where the bottom was inside) with a slight turn in at the very bottom outside to create a small shadow line. Amazing how it almost sheared off all the way around, just slightly below the level of the inside bottom.
  9. Had exactly this happen with a 15” round casserole dish I made out of a nice porcelain. First use in the oven the whole bottom cracked off just around the foot ring so neatly that I was able to save the (slip decorated) bottom and turn it into a nice cheese plate. Fine, tight clay bodies with small particle size and lots of glass in them when fired, do not like thermal shock is what I learned from that. So I would bet that the clay body is the issue in that use.
  10. Don’t have a specific kiln in mind for this yet. Just exploring what may be possible for the moment. Also keen to think it through as much as possible before actually exposing any kiln to this kind of treatment! So far it seems straightforward. Kiln will cool as fast as you want. Low thermal mass of fibre enables quick cooling, and presumably the kiln frame can take it. Open the door, blast the kiln vent, use whatever method you want to cool it down fast. I take your point about uneven cooling but the idea is that simple forms can accomodate differing temperatures....hopefully.
  11. How fast is it possible to cool a kiln from stoneware temperatures? Are there limitations as far as the kiln is concerned? Maximum cooling speed? Pretty sure this would be very hard on kiln bricks, shelves, props, etc., so let’s assume I am firing a FIBRE kiln with sacrificial kiln furniture (or none at all) and ware that is impervious to thermal stress. What is to stop me firing to top temperatures and then shutting down and then, say, running the kiln vent full blast for several hours? I have read industry does this kind of thing regularly, with incredibly fast “cool-to-coo
  12. Yes thought it might be Flir. Was looking at them a while back. They seem to be the most widely available in many different models. Good to get a real user review! I imagine I will be able to point it at myself and get some idea of whether or not I should even bother venturing into the studio...
  13. Amazing Bill and great pics! What kind of camera, software, cost, etc if you can? Seems like a new toy I need for my studio for sure!
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