Handbook for the Appreciation of Glass

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Handbook for the Appreciation of Glass

Message par Tsubo » 15 Septembre 2022, 12:34

Handbook for the Appreciation of Japanese Traditional Crafts by the Japan Kōgei Association

Blown glass can be mould-blown or free-blown. Among decorative techniques, the best known are cutting (kiriko), etching and engraving. The techniques of cut glass used on 19th century Edo-kiriko and Satsuma-kiriko have been passed over the generations and are still widely used today. Etching, engraving and sandblasting were introduced from the West in the modern period.
People are fascinated by the transparent and fragile beauty of glass. Evidence of the degree to which glass has been prized in Japan can be found in the form of the white glass bottles preserved in the Shosoin Treasury, the free-blown glass balls used on Buddhist sculptures of the Nara period (710-794), and the beads (tombo-dama) and glass fragments excavated from ancient archaeological sites.
Glass production began to develop into a modern industry and craft discipline following the introduction of European manufacturing methods and decorating techniques in the mid-19th century. Glass is made by adding agents such as soda and lime to silica and heating in a kiln to a temperature of over 1000℃. Colours are obtained by the addition of different metal oxides. The techniques of glass-making are broadly divided into forming and decorating methods, the combined uses of which give rise to a wide range of effects.

Forming methods

Chubuki (free-blowing) = A small amount of glass melt is picked up on the tip of a blowing rod and air is blown through to produce a round form that is then, while it is still hot and soft, modelled into shape with the aid of metal tools.
Katafuki (mould-blowing) = The glass melt picked up on the end of a blowing rod is blown into a mould made of plaster, clay, wood or metal. Today, wood and metal moulds are the most common.
Pate-de-verre = Paste made from ground glass mixed with a binder is put into a fire-resistant plaster mould and fired in an electric kiln. The glass melts to form a vessel in the shape of the mould.

Decorating methods
Cutting (kiriko) = Parts of the glass are cut away by moving the object against a rotating cutting device such as a grinder. Rough cutting is followed by whetstone-grinding and polishing. Only straight lines, curved lines and a limited range of circular motifs can be created by this method. Edo-kiriko and Satsuma-kiriko are the best known varieties of Japanese cut glass.
Engraving = This technique has been in use in Japan since the early Showa period (1926-1989). The area of the glass to be engraved is coated with abrasive powder and then moved against a small rotating copper plate. Different effects are achieved by using different types of copper plate.
Sandblasting = Carborundum mixed with compressed air is blown directly onto the glass to create a smoked glass effect.
Etching = This involves the application of hydrofluoric acid to etch away parts of the surface of the glass. The technique was extensively used by Art Nouveau artists such as Emile Gallet and the Daums Brothers.

Terms used
Crystal glass = Glass of extremely high translucency containing very few bubbles obtained by the removal of iron from the raw materials used.
Hakururi = Faintly coloured white glass with a high silica content of the sort found alongside examples of blue glass and green glass in the Shosoin Treasury.
Art Nouveau = An anti-traditional artistic style that flourished in France and Belgium in the early 20th century that was characterised by the use of curvilinear designs and the incorporation of organic forms.