Bad night - wide awake at 2am and tossed and turned till after 5am before getting a little bit of extra sleep, so I've been dragging myself around trying to get little things done. My clay trap needed major cleaning, the studio needed to be cleared of a lot of junk pots, which I and the hammer took care of, the pug mill towels needed to be re-moistened to keep the clay from drying out, the little gas kiln and tanks had to be moved to the back of the kiln room, and the few salvageable pots from this last little re-firing needed to be sanded, washed, and priced. Our handyman came over to take care of my house "honey do" list and I cleared a corner of a table in the kiln so he could bolt my vise to the table.
I could have taken Saturdays firing a bit higher; but I thought it was high enough to get the extra salt on the pots, which it was, but some of the re-fired, pinholed liner glazes just didn't settle down, in fact they were worse which was a puzzlement.
This little firing was worth the time and trouble though. I had some soda slip and glaze tests in there that I was happy with. I've been trying to get a warm, satin, ivory glaze and some known ones I tested were either too white or grayish, or too yellow and I finally came up with one of my own that is very promising. I'll have to test it a bit higher next time. It looks great at cone 10 around 3 o'clock. I would post a picture; but the picture I took doesn't show the true, warm color and I couldn't figure out how to use Paint Shop Pro to get the color right.
After those studio chores, I came in and got a loaf of whole wheat started in the bread machine and made us a lunch of hummus, tomato, avocado and salsa in pita bread. Then after lunch I went through the clayart archives making notes on various peoples firing tricks for the Olympic updraft kilns. Seems people have had a lot of problems firing these kilns before they were able, through trial and error to get them to fire properly. Some of the suggestions were interesting, like the one to correct back burning by wadding up screen mesh and stuffing it in the burner tube, but away from the orifice. Some said it fired best with shutters wide open, others said it fired better with shutters at 1/8". Some said no baffle shelf, others said baffle shelf but keep it only 1 1/2" from the lid, and so it went with lots of different approaches to solving similar problems.
I bought this kiln 6 years ago mainly for glaze and slip tests and maybe some refires; but had not fired it other than to seal the ITC 100 coating, until about a month or so ago. That first time, it turned out, my regulator was the wrong type for the Olympic kiln and the kiln kept kicking off. And that wrong regulator also killed the solenoid valve - an expensive replacement after only one glaze firing. So for this firing, I was starting with all the right plumbing and the speed of firing went well (no stalling issues), but the temperature top to bottom was uneven even though I was firing slowly. Next time I'll follow some of the other suggestions like raising the first level of shelves a bit more,(Olympic suggest 3" and on person said 4" worked better) and creating a goal post against the kiln wall, over the burner ports, using narrow kiln posts, to get more flame to the bottom. I'll also stagger the shelves more, even though Olympic says you can use all full shelves on this size model.
I'll be eager to give it another go when I have the time and a bunch of smaller pots. Right now I still have a lot of studio cleaning and organizing to do to get ready for the TRAC tour which starts this Friday.