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Bill Kielb

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About Bill Kielb

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  • Location
    United States - Illinois
  • Interests
    All forms of constructionist pottery, education, analysis, design and repair as it pertains the ceramic arts community.

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  1. Listening to the audio, the wheel does sound like it speeds up and slows down which would prompt me to do that same test at maximum speed just to see if the audio difference was still present. To confirm this was happening I would measure the voltage at the motor (DC volts) and observe if it is wandering. If so, then most likely a control board issue and to further guess worn power supply component or degrading drive component. That’s my best guess from the video (audio). Varying speed will definitely make it hard to center! Just to add, put the noise canceling headphones on and can
  2. Hmm, cool point to ponder. Forces acting on the inside and outside shapes. There might be a difference just by location and shape of the item. Out of the kiln, cooling. Pouring coffee, heating.......... need to create a stress diagram! Very interesting question! Further thinking, if the inside nearly always crazes first then the elastic modulus of the glaze is likely reached first so it cannot return to its original shape. Is this because of shape? Still really interesting question! Anyone have a bunch of strain gauges handy?
  3. All good actually. I wonder which in the pictures is more durable? Time to test them all? Is 0.1:0.9 ok or maybe 0.05:0.95 is the line. The point is it’s a personal preference, I really don’t have time to test them all to see nor would they become a base glaze for me. As far as the variation, effect, ability to do it, favorability in electric kilns ......... I love it.
  4. Yeah, just a personal thing really, else I would need tested results. It generally is not worth my time to test and slow cooling adds another potential for varying results. I really don’t have time to be testing combinations and testing with reasonable confidence in itself takes lots of time.. For me, I always feel I can create acceptable aesthetic results in known regions fairly easily so making it a base glaze is personally not in the cards. I also end up feeling the excess boron becomes a raw material waster but again all personal preference stuff not necessarily how others view it.
  5. I think two different glazes were used in this case which in itself can be an issue if the coe’s are significantly different. Also biggest momentary thermal gradient will likely be on the inside so filling with hot coffee often stresses the interface. At least that’s the theory.
  6. As Min said above, adding colorants would be the way to make this white. So white would be zircopax, Tin, titanium or a mixture of same as well as mason stains. With respect to these glazes generally slowly removing silica will turn them matte so you can try that in a line blend. The personal problem I have with these recipes is they have very low flux ratios 0.1: 0.9 and relatively high boron amounts for cone 6. My foundation glazes or base glazes if you will sport flux ratios in the range of 0.2:0.8 to 0.3:0.7 for durability reasons. While not a perfect indicator, this range is generally
  7. Just curious how much do they bend? Not sure if you use a cone pack such as 5,6,7 if so then does the 5 fully bend? If only a single witness cone that bends to the three o clock position would be really really close to cone 6. Just thought I would mention as I have seen folks struggle with accepting anything other than the cone touching the shelf. The three o’clock position is basically cone 6. If the cone itself is well hidden and buried by the wares it may bend slightly less. The remedy for densely packed kilns would be to slow down the final segment firing rate so everything he
  8. My guess is since fractal burning is discouraged in many countries due to the electrocution hazard you very likely will not generate fractals in clay. Clay is fairly homogeneous compared to wood and certainly won’t burn and mark like wood. Even if you could arc trail, the marks likely would disappear in the subsequent firings. Likely create steam and local fractures though. That’s my guess.
  9. Generally it’s doable post the recipe, my Britt book is buried somewhere. Generally for a true matte you can start with getting this in a favorable si:al ratio which often saves a bunch of effort and not having to rely on slow cooling. No guarantees but worth a look for sure.
  10. Best way I know to fire consistently is to fire or confirm by cone, else you really don’t know what it fires to. Not sure what holding for ten minutes actually does other than drive the kiln towards the next cone. You are used to your schedule and if successful that’s ok, but witness cones are the only way to know with reasonable confidence what things have been fired to. Many potters place them top, middle and bottom just to know how evenly their firings are.
  11. @Callie Beller Dieselis spot on but thicker glaze often accentuates or amplifies the mismatch and crazing will appear. It’s interesting to note that for crazing, the glaze is shrinking faster than the body which means the glaze Is keeping the clay in compression which actually strengthens the ware significantly as a whole. Once the glaze crazes then all the compression is lost so after crazing definitely not stronger. So very slight compression is often favored and the longer the delay in crazing generally means the fit is closer to being acceptable and slight adjustments in glaze che
  12. Trial and error for sure. Time is key for some clays, not all clay bodies need the same amount of time actually. So for difficult bodies usually dark and containing iron, sulphur, etc.... often a longer cycle is needed to complete the burnout. Many potters figure this out for their clay by experience. 200 degrees per hour is a typical rate that gets this in the 10 hour range and is reasonably slow while greenware goes through some pretty significant changes. I think if I had the teacher plus I would relabel it from 1-10 instead of overglaze , ceramic etc..... and just learn from repeti
  13. Just some thoughts here High temp wire insulation, the basic types would be MG (Mica Glass) rated to 450c and TGGT (Teflon, glass,glass, Teflon) rated to 250c with MG being the most expensive. (There are slight variants of both as well but these are the most common) Since this is already rated wire from Cromartie then we can assume it’s sized right for the load and the insulation should last. So next step is to make sure the hot parts of the kiln are well insulated and any ventilation designed into the control box is performing. Often vent holes punched in the bottom of the control box and
  14. Cleanliness of the connection is definitely key, but those wires appear as building grade and not high temperature. Any heat escaping or heating the connections is definitely a contributor that always needs to be dealt with as well. Replace the wire with the appropriate high temp. rated wire. The existing thermoplastic insulation is burning and likely causing your carbon staining. High temp. connections rarely have thermoplastic covering on them. New proper temperature rated wire, replace the existing element connection new bolt, nuts, washer.and burnish all bright with fine sandpaper i
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