Monday, February 05, 2007


I refired about 50 pots in my little updraft gas kiln. I had good success in the bottom of the kiln where cone 10 went completely down. In the middle I only got to cone 8 and I don't know what the top was probably 5 or 6. The pots that reached cone 10 improved greatly. My high silica clay got very very shiny and the slips really brightened up. The only problem was that the silica in the clay caused to wads to fuse to the bottoms of the pots so I had to grind them off. Nevertheless I came away with some first quality saleable pots from what I almost threw away. The refires were really metallic looking, not what I am always after, but in this case I liked it a lot. As a matter of fact I now have a favorite mug that came from the refire.

As to my slip problem, I am still thinking about the cause. I have conflicting information regarding body reduction. I do know I over reduced this kiln for most of the firing. I need a neutral atmosphere to get my colors to be bright. Probably with an oxidizing soak for at least one hour at the end. I would like to start salting a little earlier so that I could finish around cone 9 also. I think this will help with the color. I think my slip problem is something that is happening early in the firing, before cone 08. ? Maybe things are getting too hot too fast, or I am trapping carbon gas under the slip. I may need to improve on my bisque to be sure I am burning out all the organics. Or soak for an hour at 1650 to be sure during my glaze firing. The problem is only with the high alumnia slip. Lots of info and variables to think about.