Edo Glass, Edo Kiriko
"Precious Crystals of Edo City"

In 1834, during the late Edo period, Kagaya Kyubey, who ran a glass wholesaler in Edo City, engraved the surface of Edo Glass using garnet stone powder called “Kongo-sha“. This is known as the beginning of Edo Kiriko. In 1881, a British cut glass technician, Emanuel Hauptmann, was invited to Japan, bringing cut glass technology from England to complete the Edo Kiriko method in earnest. In addition, the style of Edo Kiriko, in which engravings are made on the surface of colored glass covered with clear glass, was established and became famous throughout Japan as an aesthetic craft. During the Taisho and Showa periods (1912~1989), several Edo Kiriko manufacturers were established and have continued to this day.

1. Waridashi

In the production of Edo Kiriko, in which engravings are made on the surface of Edo Glass, a process called “Wari-dashi (divide)” or “Sumi-tsuke (ink)” is used to mark the guidelines of the design without drawing a rough sketch.

Once the distribution of the design is written with iron oxide pigment using a bamboo stick or brush, the lines that serve as the standard for the design are carved in shallow lines.

2. Arazuri - Sanbangake

For Edo Kiriko engraving, the “Kongo-sha", a garnet stone powder that has been used since the beginning of time, and wet diamond wheels are used.

In the process of "Arazuri", the roughest Kongo-sha is used, and then the pattern is roughly carved until "Sanbangake", which uses finer one. Although there is no rough sketch, the thickness and depth of the carved lines are very precise, created by the expert craftsmen's skill and sense of balance.

3. Ishikake

The patterns carved by the Sanbangake are refined using a whetstone disk. Fine patterns that can only be cut out with a whetstone are also added at this time. This process of Ishikake completes the carving of the Edo Kiriko design.

4. Migaki

At the time of Ishikake, the refined pattern is cloudy like frosted glass. Through the process of Migaki (polishing), the entire Edo Kiriko piece is given a transparent luster.

 Polishing is done using water and polishing powder on wooden disks made of paulownia wood or willow wood, or bristle brush disks specially designed for the piece. Finally, the Edo Kiriko is finished with cloth disks to give it a glossy finish.

Glassmaking in Japan dates back to the Jomon period (14,000–300 BCE). At that time, glassware was not a vessel, but a glass bead called a “Gyoku”, and manufacturing methods and materials were different from today.

Glassware was also imported to Japan from Sassanid Persia via the Silk Road in the Asuka period (538-710), where it was called "Ruri" and "Hari" meaning one of the most precious Buddhist jewels. 

Even during the Sengoku period (1467-1615), glassware was considered a rare treasure, and it was not until the Edo period (1603-1868) that glass production and distribution to the general public began in earnest in Japan. Glass production in Japan once ceased in the Middle Ages and resumed after Portuguese and Dutch glass products were imported to Nagasaki.

At that time, it was called "vidro," and the glass-making technology was also transferred to Edo City. According to records, the first blown glass product was made in Edo City in 1711.

Later, a glass wholesaler named Kagaya Kyubei and a glass worker Kazusaya Tomesaburo popularized glass production in Edo City. Beautiful glassware products such as plates, cups, wind chimes, Kanzashi (ornamental hairpins), eyeglasses, goldfish bowls, etc. quickly attracted the folks and became familiar items to decorate the houses of the downtown Edo City.

 Thereafter, the "Tokyo Hari Makers Association" was established in 1879 and and the first European-style glass factory in Japan began in Tokyo, the renamed Edo after the Meiji period. But, due to the Great Kanto Earthquake and the bombing raids on Tokyo during World War II, glass factories in the city were destroyed.

However, many of the factories were later rebuilt and the traditional techniques were passed down from generation to generation, and have been designated as a traditional Japanese craft since 2014. 

Edo glass production has been modernized since the Meiji period (1868-1912), but the process itself and the raw materials have been handed down since the Edo period, have been kept up the tradition.

Raw materials such as silica sand, soda ash, lime, and potassium carbonate etc. are mixed together, placed in a melting furnace, and melted into candy-like form at a high temperature of 1400 degrees Celsius (2552℉).

The raw material that has been melted and is ready to be formed is called "Garasu Dane”, means "glass seed". The Garasu Dane are taken out of the melting furnace and proceed to the forming process. In order to keep the weight the glass uniform, skilled glassworkers work together carefully.

3. Forming

There are the following types of Edo Glass basic forming methods.

Oshi-Gata

Hot casting method. The melted glass is inserted between a wooden or metal female mold and a male mold, pressed together, and formed.

Chu-Buki

Glass blowing. The melted glass is rolled onto a blowing rod, and while rotating the rod, air is blown into the glass to form like a balloon, and then the glass is shaped with a tool such as a paddle. This is a one-of-a-kind process created by glassworkers with their own unique techniques and designs.

Kata-Buki

This is one of the glass blowing methods, but unlike the Chu-Buki, in which the glass is formed by rotating it in the air, the glass is formed by blowing it into a special mold. By repeatedly wetting the mold with special oil and powdered cork, a thin film of carbon is formed on the inside of the mold, resulting in glass products with a smooth texture.

4. Slow Cooling

Glass has an Annealing Point which distortion tends to occur during the cooling process from high temperatures, so cooling process needs delicate temperature control. The formed glass works are placed in a special chamber called a “Jorei-Gama (slow-cooling kiln)”, and cooled for two hour to half a day or more while maintaining a constant temperature to avoid cracks and distortions.