Tiki Mug Glaze Cracking? What Causes it? How to Avoid it?

So my brother just received a new Tiki that had cracked glaze all over it?

What causes this? Is it usable, can you drink out of it? If it's due to age then how do avoid this with my other mugs?
-Jayson

A lot of glazes are really glass type material. So it glass and its very thin and I believe it has to do with shrinking over a more stable stone body. Thats the why part.

As far as I know it's completely usable and, in fact, I think it makes a mug look more classy and inviting. I'm told it's caused by expanding and contracting of the ceramic. I imaging hand washing your mugs instead of using a dishwasher would help prevent it. Hope this helps answer your question.

F