[0cf8612b2e1e]

Sure, thermal expansion can crack ceramic. More my question is, did this really happen? The operating parameters for a ceramic cup are well known. A cup that is ok for 90C tea vs 100C tea seems like terrible design which would run you out of business if your competitor could make cups that were not known for breaking if you did not let the water cool long enough.

[dumbo-octopus]

It’s not about 100C vs 90C, it’s about the sudden change from 25C to 95C, versus a gradual change from 25C up to ~70C.