Edo glass Edo garasu
Culture heritage of the Edo period
Top-level artisans and refined techniques
What is Edo glass ?
Edo glassware is crafted in the Edogawa, Sumida, and Koto wards of Tokyo. It is also now produced in some areas of nearby Chiba prefecture, but it has been recognized as a local industry of Tokyo. This craftwork uses manufacturing methods, materials, and traditional techniques passed down from the Edo period (1603-1868). It is appreciated for being a handicraft, which results in a comfortable texture and ease of use.
Unlike mass-produced factory glass items, each Edo glassware piece is unique and admired across generations and in other countries. Edo glassware makes an ideal souvenir or gift.
In each production step, artisans use traditional techniques that have been kept alive. In addition, regular exhibitions to showcase Edo glassware and craftsmen are held to maintain the craft and present the latest creations to the wider public. Exhibition prize winners earn much renown and prestige, all of which will contribute to their acknowledgement as traditional craftsmen of the very highest rank.
The history of glass manufacturing in Japan begins with the oldest discovered glasswork, estimated to be from the Yayoi period (300 B.C.-250 A.D.). However, the simpler manufacturing methods of those days differ greatly from modern methods.
In the Sengoku period (1467-1568), glass items were rarities exchanged only among the upper classes and it was not until the Edo period (1603-1868) that full-scale glass manufacturing started. During this period, the town of Edo (present-day Tokyo) was already Japan's largest consumer city with a population of about one million. At the beginning of the 18th century, in the town of Torishio, Nihonbashi area, Kyubei KAGAYA, an important figure in glass making history, manufactured glassware for the mass-market, such as mirrors and eyeglasses. In the Asakusa area of Edo, Tomesaburo KAZUSAYA made ornamental hairpins, wind chimes, and kaleidoscopes, which enjoyed tremendous popularity among the residents.
The catalog of exhibits for Japan's First National Industrial Exhibition in 1877 lists items by Kagaya and his son Yasutaro KUMASAKI. In 1879, the Tokyo Glass Producers Association, the predecessor of the present TOBU Glass Industry Co-operative Association of Japan, was founded. Traditional techniques have been passed down from generation to generation and Edo glassware was designated as a Traditional Craft in 2014.
General Production Process
- 1. Molten glass
The production of Edo glassware was modernized in the Meiji period (1868-1912), though basic manufacturing techniques date back to the Edo period (1603-1868). The Shinagawa Glass Works, a government factory in Tokyo, adopted Western-style manufacturing technology that had been introduced in the early Meiji period, and became the driving force for development. The raw materials of glass are mainly silica sand, soda ash, lime, potassium, lead oxide, and other additives. These materials have been used since the Edo period, demonstrating that the traditions are being kept alive.
The raw materials are heated with furnaces to about 1400ºC (about 2252℉) and melted to a thick malt syrup consistency. Currently, the furnaces burn fuel oil or gas.
- 2. Shaping
Most of the production process of Edo glassware is done by hand. High-temperature control and timing are very important and considerable skill is required to make such delicate glasswork. The garasu-dane or molten glass is especially heavy and needs the group effort of several artisans to carefully remove the crucible from the furnace.
- 3. Press molding
Molten glass is poured into a concave mold. Then a convex mold is used to shape the molten glass by pressing from both above and below.
- 4. Free-blowing
Molten glass is spooled at the end of a blowpipe, which is rotated while the artisan's mouth blows air to create a bubble. Tongs and other tools will shape the bubble. The glass is kept malleable by periodically being heated in the furnace. This process is repeated until the desired shape is formed. The artisan expresses their unique vision by playing with the design, subtlety, and uniformity of the piece.
- 5. Mold-blowing
Soft glass is placed in a mold and stretched to shape from above using a spatula. In this technique as well, the craftsman's intuition is put to the test.
Glass is poured into a wooden or metal mold to give shape to the piece. For the technique of mold-blowing, air is blown into the glass, but unlike free-blowing which allows the creation of a totally free form, a standardized shape can be created many times. Any unnecessary parts are removed and the item is complete.
- 6. Annealing kiln
The temperature of the glass just after shaping is very high, and if allowed to cool too quickly, the glass will crack and break. Glass has a temperature known as the annealing point, which is about 500ºC (about 932℉). Around this temperature, strains are likely to occur as the glass cools, and an annealing kiln is required to prevent cracking. At first a temperature of around 500ºC is held for a time and then the temperature is gradually lowered over a period of at least half a day until completely cool. This process makes the glass outstandingly durable.
- 7. Product distribution
Finally, items are polished, finished, and inspected before being sent to department stores, directly managed stores, or individual customers. A wide variety of different products like tableware, sake drinking sets, or flower vases are all made from the same basic ingredients and shaped to meet so many different daily needs. Currently, some workshops have their own showroom annexes which allow the general public to directly see and handle the products.
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