Some really good results from the glost firing. The salt pig glaze has worked particularly well producing a high gloss finish. It’s a shame I now only have one of these, the other one’s bottom blew off in the biscuit firing. In fact the same thing happened with a custard jug, a vase and two bowls, so I have been panicking about having enough to fill a table next weekend. I am sure they were completely dry and although I can’t be sure they didn’t contain air bubbles, that’s quite a lot of pieces to explode, especially since it occured during different firings. I am boycotting that particular type of stoneware now clay…..I think it’s to blame as someone at the pottery experienced the same problem…at least it’s not just me. Am planning a trip down to St Agnes at the end of June to pick up some lovely Cornish clay. I just hope the clay pit is open on Saturdays.
Interestingly the celedon glaze I made worked well on the small jar, but looked totally undercooked on the mug. I presume it is all to do with where the pieces are located in the kiln, and knowledge of this will come with more experience of firings. The jar was by the burner on the bottom shelf and the mug on the top at the back. The other mauve glaze looked slightly underfired too.
All three cones were down (7, 8 & 9), although according the pyrometer the temperature only reached 12630c. Cone 9 shouldn’t have gone until about 12800c. The temperature rose steadily at 1500c per hour for the whole firing. Next time I think we need to slow it down towards the end and allow for 1 hour soak time. Not bad work though for only our second ever firing…..will be getting a lot more practice this week.