Located east of Tokyo and surrounded by peanut farms, Chiba Kogaku has been making glass in handmade clay pots for more than 50 years. The technique dates to the early 1800s, when Swiss lensmaker Pierre-Louis Guinand pioneered the method of using ceramic stirrers to mix molten glass. That process yielded a product devoid of bubbles and contaminants and ideal for optics. In 1965 a Japanese firm, Ohara Glass, refined the process with its own admixture to develop E6, a so-called low-expansion glass that’s now made for Ohara only at Chiba Kogaku.