About color-changing mugs:

The color-changing mug will appear black when it’s room temperature or cold. 

When hot liquid fills the color-changing mug, only then will the design be revealed. 

No part of the design will be visible when the mug is room temperature or below.

Are color-changing mugs microwave or dishwasher safe?

The color changing mugs are microwave safe and they can be washed in the dishwasher but the design and black coating will last longer if washed by hand. 

So it is recommended to hand wash the color changing mugs.

A testimony from a customer states:
"I personally have color changing mugs and have run them through the dishwasher many times -- they have held up but you can see some wear on the lip of the mug from washing in the dishwasher."