This kind of household appliance is called wavy line because there are wavy lines on the ironed clothes.

After ironing clothes with an iron, wavy lines will appear on the clothes. This kind of grain is usually caused by too high temperature or too high ironing pressure, which leads to the deformation and wrinkling of clothing fibers, thus forming a unique grain. This texture is similar to the shape of rolling waves, hence the name "wavy line".