What kind of processing is the 'starched finish' mentioned in the mosquito net dishcloth description, and why must it be washed before first use?

The starched finish refers to a finishing treatment in which starch is applied to loosely woven fabric to keep it stiff and prevent the threads from coming undone. Dishcloths from Nakagawa Masashichi Shoten are made by layering and sewing multiple sheets of mosquito netting fabric, a specialty of Nara Prefecture^[1], and they undergo a starching process in the finishing stage to keep their shape neat during production and distribution^[2]. When you first open the package, the fabric feels stiff precisely because of this starched finish^[3].

Fabric with starch remaining on it cannot absorb water immediately because a film covers the surface. Therefore, before using a new dishcloth on dishes or countertops, you must wash it thoroughly with water to completely remove the starch^[4]. Once rinsed in water to remove the starch, air layers form between the stacked mosquito netting layers, bringing out its original loose, soft texture and absorbency. Unlike the initial stiffness, the more it is soaked in water and used, the more it turns into a cloth that wraps softly around your hands^[5].