I didn't have much luck with this clay but I did fire it to cone 6 not 5 as recommended. The problem started way before firing through. It was a stiff clay to throw with. Although when I added stain it was softer but then a little to soft...
I rolled a slab one side white the other MQF with stain and when I made a bowl they just cracked when drying
The pink never got past drying.
The blue had heaps of cracks but I bisqued it for testing anyway. It fell apart in the glaze firing.
I also threw some with some stain
These stayed together although I didn't enjoy the throwing process they fired up well at cone 6 with my c1 test glaze and cesco mid fired
Also Finally - never ever add stain to clay unless you actually like the clay - now I have two 1kg batches of stained clay - stain isn't cheap!! and I don't like the clay. I am looking into making something small - ie some jewellery with it... such a disappointment!!