Color Line Flux is an additive that shifts Color Line paints from opaque toward translucent, so light passes through the fired color.
Using Flux Mix it into a color to open it up for translucent effects and layering. The more you add, the more see-through the fired result.
About Color Line Color Line is a range of lead-free vitreous glass paints for kiln work. They fire into the glass between about 1300 and 1510 F and turn glossy from roughly 1365 F upward, so they work across tack-fuse and full-fuse firings. Fired color runs true to the unfired paint and deepens with thicker coats. The paints are food safe once fired and are compatible with COE 85 to 96 art glass, so they suit both COE90 and COE96 fusible glass.
Firing and drying Shake the pen well before use, let each coat dry fully in air or a low vented kiln, and keep the kiln vents open below about 1200 F so the medium can burn off cleanly. Test on a sample first when exact color matters, since fired color shifts with coat thickness and the glass beneath it.
Helpful downloads What to Expect from Bullseye Glass (PDF)
Technical data courtesy of Bullseye Glass.
Description updated: July 7, 2026
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