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R Fraser

Member Since 20 Oct 2011
Offline Last Active Apr 13 2013 04:14 PM
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Topics I've Started

Large Platter Woes

04 February 2013 - 02:18 PM

I need some advice about platter related matters. I recently threw 10 platters that started with 3kg to 4 kg of stoneware (Continetal Clay Buff Stone Ware with Ochre), and 2 havecracked in the middle during drying after trimming the foot rings. I had trimmedthem a little wetter than I typically like but had time constraints as usualand felt they were sufficiently firm for trimming. After trimming I put theplatters on ware boards and covered them with plastic sheeting (formerlykitchen garbage bags). For certain the rims were a bit dryer than the center sothere was some moisture disequilibrium, but no more than any other time in thepast. No matter what I do, it seems I lose about 20 to 30% of these plattersabove 15 inches. I am very compulsive about compressing the base as Ithrow. Does anyone have a secret tosuccess with larger platters? Or should I plan for loss and just be happy it’snot half of them (yet).


My first real kiln build

25 January 2013 - 07:24 PM

I was lucky enough to come by nearly 700 used IFB wedges this fall at a Raku workshop in Southern Wisconsin that were in great shape and in January finished a 22 cuft propane fired kiln that has me pretty excited! I fired my first load last week over 7 hours to cone 10 and feel pretty happy over all with the process and outcome. Over the previous couple of years I read 3 different books and oodles of posts and articles on kiln bulding including Nils Lou and Olson's classic before taking the project on. I spent several weeks agonizing over design and layout concerns but in the end going out into the cold and setting down bricks was the thing that finally allowed me to overcome fear and inertia. The fear of buring my shop down was a motivator to be meticulous as well... I have learned a tonne in the process and may tear it down and build it again this summer! Probably not though...
Fortunately the wedges were all pretty much all the same with a minimal slope that made prefect little wall bricks when paired with matching wedges, and it gives the brick lines of the wall a wavey wonkey look I am very fond of. After 3 rows of these I spent more time trying to match the ends to make the "waves" consistent.
When I had finalized the chamber dimensions (mostly) and the design I spoke with Mr Ward at Ward Burners (invaluable resource) and checked my math on BTU/Hr input and am using 2 MR 100 burners with Baso safety and high pressure pilot and fired at 4.5 psi peak to hit cone 10. My chimney is 6 feet of brick going into Class A double wall stainless chimney pipe. The opening of the roof the pipe passes through is lined with 2inch 2300 degree cerablanket. I had cut it for the exit flue I was using when I had a fling with an old 10cuft Torchbearer updraft gas kiln. I did check the melting temp of stainless steel the morning of the first firing to be safe since the Class A pipe is rated only to 2000 degrees. I tried to make the base of the chimney have some thermal mass to take some energy out of the exhaust, but I suspect at peak temp for a cone 10 firing I am exceeding the rated temp by some couple of hundred degrees.
So Anyway, I made a light saber, now am I a Jedi?