Why shouldn't the 'unglazed ceramic' mentioned in the description be put in the dishwasher?

Unglazed ceramic refers to ware baked without undergoing a glazing process that coats the surface with a vitreous film. Azmaya's round teapot is an unglazed ceramic made by shaping clay and baking it as is^[1].

The clay's inherent rough texture is revealed. Without a protective film smoothly covering the surface, the fine pores between the clay particles are open to the outside. Generally, such a porous surface easily absorbs moisture, odors, and detergent components. In a dishwasher's high-temperature, high-pressure washing environment, detergent residue can easily penetrate into the clay, and once absorbed, those components are difficult to wash out. This is why Azmaya restricts the use of not only dishwashers but also microwaves and direct heat appliances^[2].

It must be handled by hand. When stained, it should be gently wiped with a neutral detergent and rinsed thoroughly with clean water^[3]. To completely disperse the moisture retained inside the clay, it should be thoroughly dried in the shade before storage to prevent odors or mold^[4].