What kind of processing is the 'sandblast' mentioned in the beer mug description?

Looking inside the Tebineri HARUIRO foam beer mug from Ishizuka Glass, unlike the smooth outer surface, the inner surface of the glass is hazy and opaque. This is because a matte-textured sandblast processing was applied to the inner surface of the glass^[1].

Sandblasting is a process in which abrasive particles like fine sand are sprayed under high pressure to finely shave the surface. Unlike ordinary glass that transmits light transparently, fine irregularities are evenly created on the surface, scattering light and leaving a translucent, rough texture.

These fine irregularities reveal their true value when beer is poured. On a smooth glass wall, beer merely slides and fills up, but the moment it brushes against the rough surface, carbonation is stimulated, causing fine bubbles to constantly rise up. Even simply tilting and pouring canned beer along the wall of the glass creates a thick layer of soft, creamy foam.

hmmm, it can be said that instead of retaining transparency on the inside, it focused on the original purpose of a beer mug: abundant foam.