You must let boiling water settle (stop bubbling) before pouring it into a tableware item. Therefore avoid using boiling water directly from a Quooker or a kettle.

If the item is cold it's suggested to pre-heat it with hot tap water. Pouring boiling water directly into a cool handmade cup, bowl, or mug may cause the item or glaze to crack.

However, the cracks will not affect the life cycle of the product and the glaze will not fall off.