Over the past five years I've accumulated a nice collection of ceramic baking dishes, some of them from Spain and Portugal, a few from Ross (but with reputable labels like Cuisinart).
There's no indication that any of them are cheap knockoffs or anything like that, so I trust that they can be used as designed: to bake or roast everything from whole fish, to apple crumbles, to casseroles.
Here's the weird thing: one by one, they've started to crack. First a slight crack shows up in the glaze on the inside (or enamel, for those that are painted rather than just glazed terra cotta), then the crack shows up on the bottom. One actually cracked in two with a whole fish in it, in the oven, in the middle of the cooking time.
Does anyone know why this is happening? It's been in two different ovens (in two different countries, no less!) -- one gas, one electric. I've never dropped any of these dishes, or put them in the dishwasher, or subjected them to sudden shifts in temperature (other than putting them into a preheated oven). No freezer to oven, or oven to cold water, or anything like that.
What is causing it and what can I do to avoid it happening in the future?
ETA I did see this old post on the topic, but no one seems to have an answer. I'm not so worried about superficial cracks in the glaze - it's the cracking all the way through while cooking (or visible cracking on both inside and out in the exact same spot) that has me worried.