温度・粘度
Tack Zone
Japanese: タック域
The temperature range of 700–740°C. This is the fusion temperature range where the pieces join while maintaining sharp edges, and the shape of the arranged glass remains clearly defined. Tack fusing takes place at this temperature.
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The tack zone is the temperature range of 700–740°C, during which the parts bond together while the edges (cut edges and corners) of the glass remain sharp (§8.2). In the viscosity range, this corresponds to log η of 7–8 (Pa·s); around the ASTM softening point (log η = 7.6), the glass retains its shape while exhibiting adhesive properties. The shape of the laid-out glass remains clearly defined, allowing for expressions that make use of mosaic-like designs and three-dimensional arrangements. According to Rei Chikaoka’s (2021) five-stage fusion classification, this is the temperature range in which the “tack fusing” technique is performed.
A key feature of the tack range is that, while it provides sufficient adhesion for bonding glass to glass, the shape remains virtually unchanged, allowing the contours and textures of the cut-and-placed design to appear exactly as intended in the finished product. The balance between edge sharpness and bond strength varies depending on the specific temperature chosen within the 700–740°C range. At the lower limit (around 700°C), the edges are sharpest but the bond is weakest, while at the upper limit (around 740°C), the edges round slightly and the bond becomes stronger. Although this range partially overlaps with the stick fusing range (680–710°C), it provides more reliable bond strength.
Related Concepts
Understand the characteristics of the fusion temperature zones, including the stick-fusing zone, full-fusing zone, tack-fusing, and η-T-t framework.
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.