75｜Glass Manufacturing Methods: Forming and Processing Methods 13

Hello everyone 🎵

Last week's story was about on-site information that only the owner of Kimoto Glass, who frequently visits handmade glass factories and often speaks with the president and craftsmen on site, could provide.

The glass manufacturing process involves: ① raw material blending, ② melting, ③ molding, ④ annealing, ⑤ finishing and inspection, and ⑥ packaging and shipping. We've discussed ① and ②, and also covered molding in ③, specifically free-blowing and mold-blowing. This time, I'd like to talk about thin-stem molding, which is an evolved form (lol) of mold-blowing.

A thin stem refers to the foot of a glass, like those on wine or champagne glasses. The rim is the mouth, the upper part is the bowl, the foot is the stem, and the bottom part is the plate.

Why do glasses have feet? If you hold a wine glass by the bowl, the heat from your hand will warm the wine. While there are various theories on how to hold a glass, it's generally recommended to hold the stem when drinking wine, except when standing.

Thin-stem molding is basically the same as mold-blowing. First, a blowpipe is used to gather molten glass from the cat's pot, forming a base gob. The key here is to quickly rotate the blowpipe while blowing.

After forming the base gob, the blowpipe is passed to another craftsman. Using newspaper sufficiently soaked in water and a mixture, the soft glass is shaped into an egg-like form by rotating it, similar to making sugar candy.

Once it's shaped into an egg, a little more air is blown into it to expand the base gob, then it's put back into the cat's pot to gather and expand the top gob. This is then carefully and precisely blown into a mold while rotating it to ensure uniform wall thickness.

At the bottom of the glass blown into the mold, there's a protrusion like a belly button. While heating this protrusion with a burner to soften the glass, it's passed to a craftsman at the workbench. With an awareness of the bowl's size and thickness, the craftsman skillfully and carefully pulls and stretches the "belly button" part while rotating it gently. The thinness, length, and shape of the stem are determined by this process, demonstrating the craftsman's skillful artistry in creating the stem.

After pulling up the stem, which is the foot of the wine glass, the plate part is then created. The necessary amount of glass is gathered from the cat's pot, attached to the bottom of the pulled stem, and then rotated to finish it into a flat bottom plate.

Thus, the method of pulling the "belly button" part of a mold-blown bowl to create the stem is called "pulled stem," and the method of attaching the foot part to the bowl during molding is called "applied stem." The pulled stem method creates a more naturally flowing silhouette from the bowl. Also, if the stem shape is hexagonal or multifaceted, the applied stem method is used.