The cup is dishwasher-safe, so why is hand washing recommended?

The glass body withstands dishwasher cleaning, but hand washing is recommended for the picture surrounding the outer surface^[1][2]. Ishizuka Glass's Panda Kids Pattern Glass is made of soda-lime glass^[3]. The glass itself is sturdy enough to be put in a dishwasher, but it cannot be used with appliances that apply direct heat, such as direct flame, induction, ovens, and microwaves, due to the risk of breakage^[4].

The reason hand washing is recommended is to protect the picture applied to the outside of the cup^[5]. This cup features illustrations by the creative unit Tupera Tupera, who worked on the picture book "Panda Bathhouse"^[6]. Generally, patterns printed on glass surfaces can gradually wear off or peel if subjected to repeated strong water pressure in a dishwasher, high-temperature hot water, and bumping against other dishes. Official materials do not separately state specific wash temperatures or recommended detergent standards to prevent print damage. In general, for printed glassware, lightly wiping it by hand using a soft sponge with neutral detergent is a way to preserve the pattern for a long time. Even though it has the durability to use a dishwasher, if you wish to keep the cute picture intact, it is better to care for it by hand washing.