How does the 'fire polishing' mentioned in the tableware description finish the glass?

Fire Polishing refers to a processing method that exposes the outer surface of glass to high-temperature flames to smoothly melt it. After glass is molded in a mold, a finely rough texture easily remains on the cut edge or rim. When the glass is lightly baked in flames at this time, the outer surface melts gently, causing unevenness to disappear and be neatly rounded. Unlike the method of grinding it down by rubbing with abrasives, it features preserving the glass's unique clear and transparent luster without damaging it.

Ishizuka Glass's Tebineri series is finished with this fire polishing technology^[1][2]. Although the shape itself is bumpy, the surface that touches hands and lips is finished smoothly without catching. When drinking beverages or plating food, the rim touches gently without being sharp, allowing comfortable handling in everyday life.