Wissmach Crystal/ Dark Blue with Luminescent coating (base color code 96-30) is a Prisma blend in COE 96 kiln glass, a 3mm sheet with an iridescent surface, tested for fusing compatibility. Wissmach's own name for the base blend is Midnight Blue Tr/Crystal.
Appearance This is one of the louder sheets in the Luminescent line, with saturated magenta, cobalt and aqua swirling across the surface like oil on water, trading places as the light and viewing angle change, and the effect shows in ordinary room light. Underneath is a Prisma blend where the first color in Wissmach's name leads, so midnight blue dominates the base with crystal streaking through it. The swirl is unique to each sheet, so no two are identical.
Striking Wissmach notes that its Opaque and Prisma colors may strike, firing to a deeper or denser color than the raw sheet shows. Expect the base blend a little richer after firing, and test a chip if the exact shade matters.
Luminescent coating The Luminescent coating lays an intense shimmer over the midnight blue and crystal base, swinging through magenta, cobalt and aqua as the light and viewing angle change. The coating is a low fire surface layer and it is heat sensitive. Fired face up, heat and oxygen can burn it away. Wissmach recommends reverse fusing with the coated face down on a flat kiln shelf and keeping the top temperature at 1400 F or below. Do not cap the coated surface with clear glass, capping makes the coating disappear. Keep any later firings below 1250 F. For a full fuse with two 3mm layers, Wissmach’s Luminescent schedule runs 400 degrees F per hour to 1225 F with a 30 minute hold, then 600 per hour to 1400 F with a 10 minute hold, cooling as fast as the kiln allows to 960 F for a 1 hour hold, then 100 degrees F per hour down to 700 F. Results vary sheet to sheet, so test fire a small piece first.
Reactions The base blend carries the copper marker on Wissmach's COE 96 chart. Fired in direct contact with a sulfur bearing color such as String of Pearls, Oyster Pearl, Gold Tone or the red and orange family, it can form a darker reaction line where the glasses meet. Results vary by batch and firing, 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 without the coating (plain sheet) .
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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