34｜The History of Glass: Japanese Glass Manufacturers, Hand-Blown Glass Factories (Part 4)

Hello everyone🎵

Thank you for always reading my humble old man's blog, and I am delighted to receive your warm messages and comments. Thank you. Please feel free to share your opinions without reservation.

Now, in the introduction of Sasaki Glass Hard Strong rim-tempered glasses, I explained fully tempered glass for comparison with rim-tempered glass. Fully tempered glass is less likely to break and easier to handle. However, if the glass gets a small scratch or external force, it will shatter into small fragments like a car window. I mentioned that it might scatter as if it had exploded at that time, and I received a suggestion that further clarification was needed.

The clarification is that the glass doesn't break simply with a small scratch or external force. Instead, very rarely, fine fragments may scatter when conditions such as a small scratch, a sudden temperature change, or an external impact like hitting it occur simultaneously. Also, though extremely rare, it can sometimes spontaneously break due to impurities mixed during the manufacturing process and stress generated within the glass. Improvements have been made through manufacturing process control and review. Furthermore, there's a growing number of tempered glasses being manufactured using a new technique called ion exchange, rather than the physical manufacturing methods. I'd like to talk more about these manufacturing methods at another time.

In February 1957 (Showa 32), Sasaki Glass was the first in Japan to begin automated machine production of glass instead of handcrafted methods. This became a major turning point in the glass industry. In parallel with Japan's rapid economic growth, the affluence of common people increased, and as lifestyles became Westernized, opportunities to use glasses at home grew, leading to an explosive mass production and sale of glasses. As my old man would say, it was an era where glasses sold like hotcakes, like sprinkling water in the desert, and there weren't enough in stock. It truly feels like a dream story now (lol).

Sasaki Glass's Tokyo factory in Sumida did not have enough production capacity, so they built a new Yachiyo factory in Yachiyo City, Chiba Prefecture, in 1963 (Showa 38) as their Chiba factory. New automated production facilities were installed there, and at its peak production, they manufactured glass 24 hours a day with three automated machines, combining the output from both Tokyo and Chiba.

How many glasses do you think one machine can produce???

Although it depends on the shape, form, and production status of the glasses, it is said that approximately 100,000 pieces can be produced per day at maximum. Since Sasaki Glass alone produced with three machines, that's a maximum of 300,000 pieces per day. As an aside, if you total the production capacity of other companies that later started automated production, it reached 700,000 to 800,000 pieces per day, or 250 million pieces annually operating 24 hours a day. This was an astonishing production volume of glasses that exceeded Japan's population, leading to various phenomena.