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fergusonjeff

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  1. Every couple months I switch between various white cone 10 clays and mostly red cone 6. I get it as clean as I can by hand without taking it apart and then run two batches through. I mix the two batches and run them through again. No problems either direction. I think the only big concern would be switching from some dark stone ware to a fine porcelain - if you really cared about keeping the porcelain perfectly white.
  2. fergusonjeff

    Rim of bowl is jagged

    It looks like the problem might be occurring before pulling up the walls. It kind of looks like the clay is being folded over as it is first opened. This would create a layer of slip that prevents the top of the bowl from staying firmly attached to the bottom. I am probably not explaining this very well. Be sure to keep the clay together as you open and don't let the clay fold over on itself.
  3. fergusonjeff

    Sabotage?

    Where are you located? If you are able to ship a piece to me I would be happy to take a quick look and see what the substance is. I have XRF equipment that is very quick at determining qualitative bulk chemistry. It is really easy to identify most basic metals (Cu, Co, Ni, Fe, Mn...)
  4. You might try a faster cooling. I have some really nice variegated glazes that go matt and bland with a slow cool. I just crash cool and they come out fine in both my 3 and 10 cubic foot kilns.
  5. As someone with a lathe and a woodturning background, it is easiest to do the shrinkage calculations and then aim just a bit smaller. It is much easier to slightly turn down the cork than to get the pot perfect. I just did this recently when making a replacement pot for someone who wanted to re-use their own cork.
  6. A few inches should work. I built mine in the winter and the small amount of mortar froze the form to the arch, so it would not drop. Fortunately I had planned for this and was able to disassemble it from the ends. It looks like yours is the same way. Good luck.
  7. I mix porcelain into my stoneware all the time (~25%) and have no problems. It is well-mixed in the pug mill. I have also thrown pieces with 1/4 or 1/2 porcelain smashed together but not even wedged to get swirled clay in the final piece. the biggest issue is different throwing properties/moisture levels.
  8. The Amps seem about right. The kiln is only 2.3 cubic feet.
  9. For the standard gas kiln a permanent set up is reasonable, but I just use a flexible 50' hose for my Raku kiln and for getting a little gas going to start the big wood kiln. I ran a long propane line underground to get heat to the studio (about 40-50') but added a fitting on the outside of the building. I bought a 50' hose from the propane company that I can just attach when needed. This type of setup might work for propane users needing only occasional gas for smaller uses (like Raku).
  10. Same as Denice. I usually mix the Speckled buff with other cone5/6 clays. Will get occasional warping with things like yarn bowls so I add a little extra sand and fireclay. For usually items like bowls and mugs that WC-403 clay does fine at cone 6 (and even cone 7 when first firing my new kiln). I also bisque to cone 04 and this helps burn off some stuff that can cause glaze issues.
  11. I have been using the SS20 daily for about 3 years now. Here are some answers to your questions. 1. Has anyone gotten HOLES in the center of their clay logs from a PP? Only at the beginning of the pugging. Not more than 5-6 inches with some air pockets. 2. Do PPs also have to pug super slow? My Baily was fast. I use a top speed when pugging. usually takes about 1-2 minutes to pug out 30-40 pounds. 3. Does a lot clay get all stuck in the lid? Does it have to be cleared all the time? There is definitely some that builds up on and around the lid, but not a problem to scrape off every once in a while. If it builds up around the seal it can dry out and create some vacuum leaks, but still easy to clean off. 4. Does water tend to get shoved up into the lid area clay, not allowing it to affect the batch? Mark and Glazenerd have addressed the water issue. Getting the "spins" is often a problem when adding water, but if added in small amounts in the front of the chamber it usually works itself out. 5. Is the issue with sucking back-in the clay for the De-Airing to reach both chambers at least a "reliable" and a repeatable task for success? With the PP, the vacuum is first created in the rear chamber. I usually need to start pugging to get the seal to pop and vacuum out the clay chamber. It usually occurs after pugging out about 5-6 inches. I then reverse the direction and pull the clay back in and mix for a few seconds. then just pug everything out at full speed. 6. Can you mix batches a little wet or a little dry to suit your needs, without major issues (not pugging, holes, bubbles, etc.) I adjust wetness to what I plan to throw. there are definitely points of too wet or too dry for it to work well, but usually those are outside the range you would want to use anyway. 7. Are single augers, though stronger and won't break down like dual augers, doomed to have these issues? Not sure. no experience with dual augers. 8. I can't spend more than $5,000 I think the SS20 will slightly exceed that budget. I tried for months to find a used one and gave up. Don't bother with the used list on the PP website. Most of the ones still listed sold many years ago.
  12. fergusonjeff

    Peter Pugger VPM 20SS

    Maybe they developed a new self-opening clay system. Just slap the pugged sections with proper alignment and you are ready to start pulling. Actually this does seem like a problem. I get some air pockets in the first few inches with the peter pugger, but I just toss that into the next batch.
  13. The one I fire is exactly like the one in Neil's diagram. I use about 0.8 cords of waste wood (combination of salvaged barrel, pallet, and lumber scrap) per firing.
  14. I currently have one of the catenary cross-fire kilns that Neil just mentioned. I typically fire in about 12-14 hours and can get decent ash. It also does well with most glazes. I often sprinkle a little ash mixture (50% ash and 50% neph Sy) on the wet glazed surface for a little extra ask kick-start. I use predominantly wood scrap from Amish pallet makers a little north of me and scavenged pine. The wood is free, and if I did not take it they just spread it out in big piles and burn it.
  15. fergusonjeff

    Skutt kiln long firing

    Usually the elements go slowly. Going from 8.5 hours to 12 is a really big jump. Can you confirm all the elements are glowing while firing? A quick jump in firing time (assuming the thermocouple is working correctly) might be from a single elements not firing due to damage during the move. Might also explain why the bisque was only a little slower and the glaze was a lot slower. The kiln could probably compensate for the bad coil during the lower temps.
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