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About Joe_L

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    Learning, learning, learning....!
    Experimenting with Single Firing?
  1. I've mostly single fire and can second a lot of what has been said. Get Fran Tristram's book "Single Firing". Your clay body and glaze both need to mature at the same temperature, and this is what you fire to. You can brush, dip pour or spray but you may need to adjust the thickness and the time of application (leather hard, dry etc) - as with everything in pottery experiment and testing is the way forwards as what works for one person may not work in your situation. Many standard glazes will work as they are but some glazes will need adjusting if their drying shrinkage is different to the body shrinkage (glazes with moderately high clay content helps here), or adjust the timing of when you apply. I had one commercial glaze would flake off after drying when I applied it on leather hard so I applied it on dry and it was fine. Some glazes will come out more or less the same while others will have altered colour or surface texture. You can get more interaction between the glaze and clay - what is it they say, something like "the glaze is the lens you look at the body through." Again, test and use what works for you. If you pour or dip dry ware you may have problems with the shock of new water absorption causing damage. Wall thickness needs to be even and avoid sharp corners, not too thick, not too thin. It can help to lightly spray one surface with water when applying glaze to the other surface. Sometimes when applying glaze to the second surface the absorbed water drives air ahead of it causing blisters on the first surface - changing your sequence or the timing between applications can help. Firing schedule - basically you are combining the bisque and glaze firings in one so need to go slowly and good ventilation up to 800-900C to burn everything out, start with your normal bisque profile and at the end of that you can ramp up to highest temp fairly fast. Good luck! Joe
  2. New Kiln Prep

    Sounds like you're on track. Which controller do you have? Don't know why you'd block the exhaust - I've fitted the chimney to the port and fitted a flexible duct to take the fumes away which keeps the smell down a bit (and also use an extract fan in the studio to keep fresh air exchanging).
  3. New Kiln Prep

    Hi Nettle, I have a Rohde Ecotop 43L. My manual states "During the initial firing you can also burn in the hollow stilts and furniture...". Elsewhere, it shows a photo of what I would call shelves and props and calls them "stilts and plates" and says these should be burnt in before use, referring back to the section on initial firing. I must admit I kiln-washed my shelves and burnt-in the whole lot in the first firing on the assumption there's not much in the kiln wash to compete with the elements for oxygen (having not taken advice from Marcia first!). Remember to tighten up your tensioning bands after the first firing (I checked - you do not need to do this after further firings.) Joe
  4. That moment when you visit someone's house you haven't been to for a long time and pick up a jug off the shelf to see where it came from and discover it's got your initials on...

    1. Show previous comments  1 more
    2. Chris Campbell

      Chris Campbell

      Sometimes I have no memory of having made that kind of work ... funny to me but not them ... I look through old slides ( I did say old ) and love to be surprised by what I used to make. Maybe I will add a page to my site if I can figure out how to transfer the slides with my printer.

    3. Joe_L


      You used to be able to send slides off for processing, dunno if you still can. Or get one of those little scanners but I've never found the quality good enough. Slides have such high contrast it doesn't come out well.


    4. glazenerd


      Nice bit of satisfaction.

  5. Circumstances have kept me away from clay for the last 2 months.I feel my creativity will take a while to return. Fixed by craving with a family holiday in France and found some excellent ceramics in Burgandy, and a nice bowl now sitting on my dining table. Hope to get back to the wheel soon...

    1. glazenerd


      Life does that sometime.

    2. Joe_L


      And even better, this weekend is PotFest. Always a great day out. http://www.potfest.co.uk/in-the-park/


  6. Don't know about early signs of artistic tendency, but an early sign of messing about with mud was taking up caving....
  7. I've used Toasted Stoneware in the past and quite like it. Have you done any seepage, absorption or warp tests on it at ^6? It did some tests but then realised my kiln was overfiring to ^8 - at that temp it has barely measurable absorption and by ^9 there is slight but noticeable warping. Would be interested how absorbant it is at a real ^6. Thanks for the heads-up about B17C. I've just bought some V9a to test. (I'm currently using ES10 now which is a smoother ES5). Joe
  8. S- Cracks

    Only ever had one S crack (fine white stoneware) which was thrown off the hump. I tend to compress my bases carefully and throw fairly dry anyway. (Would like to know more about this Japanese technique but that's off topic...) Once had a mug with parallel cracks but that was due to accidentally flexing the bottom after turning it too thin. Joe
  9. Kiln Conversion Updraft Downdraft Chimney?

    Effectively, yes. Try something like one of these (not sure what outlet you've got near you, Maplin might have something similar) http://uk.rs-online.com/web/p/bipolar-transistors/6562037/ http://uk.rs-online.com/web/p/bipolar-transistors/7740711/ Spot the hole for a bolt to attach to a heatsink if it gets too hot.
  10. Kiln Conversion Updraft Downdraft Chimney?

    Even if its ok for current capacity you still need to watch the power dissipation (voltage drop across the transistor at each speed setting x current at that setting), needs to be less than Maximum Power Dissipation (0.625W in this case). Also watch the temperature, put your finger on it and see its not getting hot at various speed settings. I'm not suggesting you have a problem, just something to watch out for if failure mid-firing would be a nuisance.
  11. Kiln Conversion Updraft Downdraft Chimney?

    Depending on the fan that transistor might need a heatsink?
  12. Cowpats. Tried it last year, got 800'C first time. I'm sure with a bit of thoughtful design that can be increased a bit.
  13. Great thanks, I'll hunt for the closest matches. I hadn't clocked BPS might be them.
  14. Building a basic starter kit for glazes (I'm beginning to make a shopping list following RonSa's discussion). Yes I've seen that you can import material specs but wondered if someone had already done it for common items from any of the UK suppliers e.g. CTM? I'm assuming that adding them to Insight will help if I need to do any conversions from US recipes.
  15. Anyone got an import file for common materials from UK suppliers please? Joe