Wissmach Midnight Blue Transparent (color code 96-20) is COE 96 kiln glass, a deep saturated blue in a 3mm sheet, tested for fusing compatibility.
Appearance A rich, saturated blue sitting between royal and cobalt, still passing plenty of light despite its depth, with a generous scatter of the fine seeds typical of handmade rolled sheet. A single fired layer glows on a lightbox, and doubling the layers pushes it close to a true midnight tone.
Working notes Wissmach’s recommended full fuse schedule for a 6mm project made from two 3mm layers: heat at 300 degrees F per hour to 1225 F and hold 30 minutes, then 600 per hour to 1460 F with a 10 minute hold, cool as fast as the kiln allows to 960 F and hold 1 hour, then 100 per hour down to 700 F. These numbers come from Wissmach’s current published firing guidance. They are guidelines, not guarantees. Kilns differ, so fire a small test piece first.
Reactions Midnight Blue is a copper bearing color on Wissmach's COE 96 chart. In direct contact with sulfur bearing colors such as String of Pearls, Oyster Pearl, Gold Tone, Honey or Yellow, it can form a darker copper sulfide line where the two glasses touch. Reactions vary by batch and schedule, so test the pairing first.
Format and sizes Sold as a 3mm sheet in 8" x 10.5", 10.5" x 16" and 16" x 21" sizes. Choose your size from the options on this page.
Fusing and compatibility Tested compatible with other Wissmach COE 96 kiln glass. With glass from other makers, a matching COE number alone does not guarantee compatibility, so fire a test tile before committing a project.
More of this color Also available with a Luminescent coating .
Helpful downloads Wissmach COE 96 Kiln Glass Catalog
Technical data courtesy of the Paul Wissmach Glass Co.
Description updated: August 13, 2026
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