Why do both sides of the mini double-sided washboard have different corrugated shapes?

One side has well-defined angles, and when turned over, it is a gently rounded surface^[1]. Kajidonya's mini double-sided washboard was made with different shapes on both sides to suit the condition and level of contamination of the fabric to be washed^[2]. When dealing with stubborn stains or when meticulous washing is required, you can scrub vigorously with the angled side, and when fabric damage needs to be relatively minimized, you can choose the rounded side for washing^[3].

This tool serves not only as a washboard but also as stainless steel soap^[4]. Generally, when stainless steel is rubbed under running water, it has the property of binding odor molecules to reduce odors remaining on the hands. When maintenance is needed, it can be conveniently cleaned by placing it in the dishwasher^[5].