Right. . .

Before I start on the rest of it, just to tell you it was a wonderful sunny hot day today! Just beautiful.

OK lets see if I can remember all the things that you helpful wonderful bunch have asked me.

The kiln has always been cooler at the top, ever since new, I know heat should rise so heaven knows how this happens in a top loader. The good old kiln guys came up and fitted controllers to each bank of elements for me some time ago. This works great, allows me to control each set of elements separately and allowed me to even it all out (until I got the problems with the power supply.) The last glaze firing after the new stronger elements were done the other week was very even, but thinking about it maybe it wasn’t packed as densely as this last load. The elements are all taking in the same amount of power according to the little machine that Paul has that tests these things.

I’ve got cones coming out of my ears at the moment (doc says it’ll clear up eventually but is a risk of the job.) I have one glaze and have always used this one, it’s pretty basic, 75% lead bisilicate frit and 25% the red clay body I throw with. It’s a good un but if it gets too hot it then shimmers on cooling. The cones on the left in the pic are from last weeks lovely firing and those on the right from the weekend’s disaster. I’ve put on a bisque today, full of cones and very loosely packed so I can at least see if that makes any difference to the evenness.

My plan at the moment is to wait to see what these bisque cones look like, then to not put so much in the bottom, open the pack out a bit, and to keep my fingers crossed and to do some more glaze tests anyway and to hope and hope and hope. If all that doesn’t work then it’s time for plan b and a job in Tesco!
What I forgot to tell you also is that I got Paul back home on Saturday evening hurrah! (He went off back to work in Middlesburgh very early this morning again sadly) Anyway while he was here I asked him if he could show me how to get pics off my camera onto this computer and he pointed out the little camera card sized slot on the front of the computer that even says on it SD card point. Oh dear oh dear.
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9 Responses to Right. . .

  1. Hannah, Last year my kiln which had always had incredibly even firing top to bottom began firing unevenly. I fired the kiln empty once for several hours so the temperature got up to around 1000F. Then I looked inside at the elements. The bottom ring and another near the top were either not red at all or were very dull while the others were bright red. So I decided to replace the elements. Most people I talked to were surprised I needed to change elements so soon (after 95 firings over 3 years). I was told that I should replace all the elements even if some were still functioning. So I did. I was very surprised as I removed the elements, very carefully so not to harm the brick, to find that the 2 poorly functioning elements were broken. I was so puzzeled since I could not figure out how they got broken. But someone reminded me that if a bit of glaze or broken bisqueware got on an element it can break that element. I guess that is what happened to me. I do vacumme out the kiln–but not always and probably pretty carelessly. I am very attentive to the task after a piece of bisque has exploded. So I wonder if you have a bad element. Gay

  2. Hannah says:

    I thought that originally, and did replace them last year as they were very tired. When the chap came up the other week because of the shortage of power actually being available on the tcable before it even gets to the kiln, he ended up changing them all again to put stronger ones in. It is consistantly hotter at the base and I have changed the contactors too so can’t believe that there is always the same one not working. That would just be too wierd.

  3. doug fitch says:

    Oh dear, what a nightmare. Are you getting your Lead Bisilicate from the same supplier as always? I had to change supplier because of the bubbly thing that happened, so the quality of LBS does vary. It might be worth increasing the amount of LBS, maybe 80% LBS 20% clay. When the glaze shivers does it lift the slip too? What’s in your base slip? Is it happening to all colours? It may be worth giving Paul Young a shout and having a word with him, he’s pretty clued up on stuff. Strange that there should be so much variation top to botom, do the new elements look like they’ve more loops in them than the old ones?

  4. doug fitch says:

    By the way, great looking pots in the sunshine

  5. ang says:

    cool thanks fro more info – ok new train of thought can you put some pieces in someone elses kiln? that way you’ll know if it’s the glaze mix and my first thought when you spoke about power supply before maybe its an actual drop in supply while firing? have you tried firing when you think others may not be using so much? what I mean is we used to have terrible probs. across dinner time about 6pm cooking & heaters on! weird I know , we now are in a diff. location and have 3 phase power everything’s fine now.. Oh and on a lighter note – sometimes it takes 3 kiln guys, 1 electrician and a combustion engineer & 20 potters to figure out the most simplest thing like the timers not working!!

  6. Hannah says:

    Hi all, I do have lots of potter friends round here but they are all chaotic for the Spring Fling at the moment unfortunatly. I have a little test kiln and in that things are ok, it is tiny though and most things I make won’t fit in.Doug- MORE LEAD!!!!!! Is that allowed? I thought I was on the edge of sanity at the moment. I have indeed already email the Paul Young oracle. Sometimes it takes the slip off, sometimes not. I thought it was more over the black than the honey but actually I think it’s petty not that choosey. White is hyplas 71 and black is red body clay with iron and manganese.The power could indeed be the eventual problem, that’s the kiln mans feelings which is why he put the different elements in this time. We only have single phase and there isn’t much spare capacity on the line. The kiln was built to use 10KW as there was 12 or 13 spare at that point in time. For some reason though it is now only getting 8KW hence tthe different elements required. I tend to fire overnight just to try to eliminate the chances of the supply being overloaded.

  7. ajsimmons says:

    Hannah…if i’m not allowed to go and work in Tesco neither are you!!!Get your wood firing one going and use that as demonstration at spring fling….no pots to sell just a beautiful kiln!It will work out in the end, your work is so fab!A x

  8. potterboy says:

    Yes – things will work out ok. The wood-fired demo is a fab idea, but even more risky, perhaps. But much more fun!The top loading would suggest cooler at the top I think – my lid doesn’t fit at all well, but then, there are gaps btw all layers of bricks. Measuring the difference btw top and bottom, as Ang suggested, would be worth doing I think.I’m sure Paul will sort it out – Matt Blakely is a bit of a glaze whizz too, but of course, not earthenware. I think iron and manganese will act as a flux too, so your glaze might be behaving differently on those pots – especially at higher temperatures. It might even be worth using less LBS too to see if additional clay content can help buffer the expansion differences a bit?Hmmm… I’m not even sure *I* understand what I’ve written their.I’ll shut up… sure I’m not helping really…I do at least have my fingers and toes crossed for you, though.

  9. Hannah says:

    No that does make sense Andrew, have got one test at 70:30 mixed and will try an 80:20 too as Doug suggests. The iron and manganese thing is interesting as is Potter Paul’s bisque cooler pots not shrunk as much thought. Oh heavens so much to test. I should employ you to come up and test everythi ng for me once you’ve finished work, I could do with a technician!

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