I doubt the interrupted firing caused crawling. By cone 1 everything was more than bisqued, yet very few cone 6 glazes should show any sign of fluidity.

The few times we've done once-fired pieces, I've found the more fluid glazes work better probably because they heal if they get blown-off in places when the greenware off-gasses.

Thanks.  One of the poorly performing glazes was Raw Sienna from the MC6 book, a semi-matte glaze.  On the other hand I used "dry red brown" a high iron matte glaze, and it did fine.  This was an interesting experiment.  I'll have to think about whether I want to continue single firing.

The single firing group has been pretty inactive. If I were to guess why, it would be because of the little difficulties that can be overcome one by one, but taken in total they seem to make the process more problematic than simply bisquing and glaze firing like most people do. 

I mostly have gone back to conventional firing myself, but if I have a piece that needs a superfast turnaround I will occasionally add the single fire pieces to a normal load and then run a single-fire schedule on the kiln heating very slowly,through 500 degrees and through the 1000-1400 degree range and then just my normal firing schedule.

The biggest problems seem to be when glazing the raw ware. Cracks in the thin areas showing up when drying, crawling before and during firing, and bloating during the firing.

Not all clay bodies will tolerate the process, not all glazes will work well. But if you wanted to develop a line of pieces that you plan to reproduce on a production scale, single-firing could make economic sense. I don't think it makes sense for an art potter constantly making entirely new creations and changing glazes and techniques.

I'm sure Steven Hill is still single-firing, but I read recently that he has upped his firing temperature back up to cone 8.  See the article on his website at http://www.stevenhillpottery.com/glazing/firing/

Feel free to ask questions. I will post this reply to the group.