Eli5: Why shouldn’t you put home made ceramics (a mug, for example) through the dishwasher? If they can withstand the heat of a kiln, surely a dishwasher is fine?

Question

I mean, I put them through the dishwasher sometimes anyway, but I’m told I shouldn’t? 🤷🏻‍♀️

In: 5331

Answer 1

Usually it’s fine. They can go in the microwave too (maybe better not with a metallic glaze). If they had water trapped in the clay somewhere, the thing would have cracked in the kiln.

The glaze might not be as sturdy. You can see that in industrially made things too, the glaze cracks all of a sudden. It’s called “crazing” and happens when the glaze is under stress. Again, not so much of an issue in itself, it’s just the glaze, the cup won’t break completely along those lines. But it’s no longer perfectly sealed there. Water (and with bad luck bacteria) can get to the way more porous clay. And heating a crazed cup that has soaked up water suddenly (microwave, dishwasher on hot, or just pouring hot water in) could chip fragments of the glaze off or break the cup.

But usually it’s fine. That’s like the labels on wool or silk clothes “dry clean only”, there can be reasons for it, but that it’s wool/silk is *not* it. Sheep don’t shrink in the rain.