Bullseye Stiff Black (style 000101) is a 90 COE fusible glass sheet, an opalescent color for fusing, slumping, and kilnforming.
Cold characteristics Uniform color.
Working notes Stable. No color shift. Compared to Black (000100), Stiff Black (000101) has a slightly higher viscosity, meaning that it is a stiffer glass. In most kilnforming applications, Black and Stiff Black can be used interchangeably. Kilnforming applications where differences between Black & Stiff Black might be noticed include working with elevated drop ring molds and kilncasting. Stiff Black was originally developed for glass blowing purposes such as the Roll-up Technique. Using Stiff Black in kilnformed panels for this application creates a more uniform viscosity, which is easier to control.
Reactions This color is not reactive. It can sit next to any color without forming a reaction line, which makes it a dependable choice for bases and backgrounds. See the Reactive Potential of Bullseye Glass chart to find the colors that do react.
Format and sizes Thin-rolled sheet, 2mm, with a rolled edge. The thinner sheet is ideal for overlays, fine detail, and controlling stack thickness. Available in the sizes shown above.
Fusing and compatibility Tested compatible with other Bullseye glass. When you combine it with glass from other makers, matching COE alone does not guarantee compatibility, so fire a small test tile first.
More of This Color The same Bullseye color in other forms: 3mm Sheet · Frit · Stringers .
Helpful downloads What to Expect from Bullseye Glass (PDF)
Technical data courtesy of Bullseye Glass.
Description updated: July 7, 2026
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