素材
A-ski Glass (Santoku)
Japanese: Aスキガラス
COE90 flat glass manufactured by Santoku Kogyo. This is an art glass that is readily available in Japan and is used in crucible melting and at institutions such as Musashino Art University.
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A-ski Glass is a COE100-series flat glass manufactured by Santoku Kogyo Co., Ltd. (Japan). It has a soda-lime-potassium (SLS) composition, and its viscosity-temperature curve is similar to that of Bullseye COE90, though there may be slight variations depending on the production lot. As a type of art glass that is readily available in Japan, it is widely used at domestic educational and research institutions—such as the Glass Department at Musashino Art University—as well as in artists’ studios. It is one of the brands included in the author’s (Rei Chikaoka) viscosity-temperature curve reference system (§14.1).
The glass transition temperature (Tg) of A-Ski glass is approximately 485°C, similar to that of the Bullseye series, so the COE 100 series firing program (based on full fusing at 780°C and annealing at 482°C) can be applied almost as-is. However, it is recommended to verify the appropriate temperatures through calibration tests specific to each electric kiln. This material is also used in crucible melting techniques, and in some cases, cullets—rod-shaped pieces drawn from molten A-Ski glass—are utilized as raw material. While the flat glass market in Japan offers a variety of colored products, they do not come with technical documentation (such as TechNotes) as comprehensive as that provided by Bullseye.
Physical Data (Manufacturer-Reported Values)
Softening point: 664°C; yield point: 566°C; slow-cooling point: 481°C; glass transition temperature (Tg): 473°C; strain point: 436°C; density: 2.52 g/cm³. The COE (coefficient of thermal expansion) is 100 × 10⁻⁷/°C, as published by the manufacturer. The composition (wt.%) is SiO₂ 69 / Na₂O 12 / K₂O 7 / B₂O₃ 1 / CaO 3 / Al₂O₃ 2 (lead-free).
Product Features
It is sold as a glass batch for crucible melting and is readily available in Japan as an art glass. It is used in combination with the “Sunglass Color” line (Sunglass Co., Ltd.).
Country of Origin
Japan. Manufactured by Santoku Kogyo Co., Ltd.
Related Concepts
Bullseye COE90 (bullseye-coe90) · Bullseye Tekta (bullseye-tekta) ・Gaffer Casting Crystal (gaffer-casting-crystal)・COE・VFT Equation (vft-equation)—use these together to understand the viscosity characteristics of each glass brand and their impact on firing design.
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.