Crystal Glaze Sink

Do you have any idea how hard and rare it is [for me] to get a big porcelain piece like this from a crystal firing? Not that it's that big- only 30 cms diameter- but sinks have always given me problems- the extra weight of clay [for resilience] and that hole in the bottom both add up to a recipe for trouble. My sinks crack while drying,in the bisc and in the glaze firing,where they also warp.This one went into a kiln that's only 34 cms across [this in itself no simple task],so I was concerned about the closeness of the rim to the kiln elements,given the speed of the firing. So expectations were low this morning,and subsequent joy [on opening the kiln] great.Then,of course,came the somewhat nerve-wracking process of separating the sink from its glaze-catcher base,to which it becomes firmly welded during the firing,and then the subtle art of grinding down the base with a diamond-disc angle-grinder.That's ten hours-plus of firing for one piece [it filled the kiln]. I think I'll try another one...