And lo and behold the whole construction held together, rather well actually, and looks a whole ot better than the ware chamber.
The new arch is a proper roman arch and considerably higher than the old one. Had we thought about it we should have lowered the supporting walls by a course or two. We weren't sure how this extra volume of the fire chamber would affect our ability to reach temperature. The results, after 40 hours of stoking dry pine slab wood was cone 10 melted almost throughout the chamber (middle back cone 10 was just down). To my eye, the best firing yet, some lovely natural ash glaze, good crusty effects in the firebox, not too many collapses, not too much reduction. We could spend more time building up ash deposits in the next firing being fairly confident of achieving a good temperature if we have good wood.
More detail of the firing log soon. photos next