Wissmach Crystal/ Reactive Blue (color code 96-27) is a Prisma blend in COE 96 kiln glass, azure blue with subtle crystal streaks in a 3mm sheet, tested for fusing compatibility. Wissmach lists it as Reactive Blue/Crystal, with the blue leading.
Appearance A clear azure blue that reads nearly solid at first glance, with faint paler vertical streaks where the clear crystal thins the color and a scattering of fine seeds typical of handmade rolled sheet. Reactive Blue is first in Wissmach's name and clearly dominates here, the crystal showing as subtle lighter bands. The streaking is unique to each sheet, so no two are identical.
Striking As with Wissmach's other Opaque and Prisma colors, this blend may strike to a deeper or denser color once fired. Expect a slightly richer result than the unfired sheet shows, and test a chip first if the precise shade matters to the design.
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 Reactive Blue brings copper to this blend on Wissmach's COE 96 chart. In direct contact with sulfur bearing colors such as String of Pearls, Oyster Pearl, Honey, Yellow or the red and orange family, it can form a darker line where the glasses meet. Results vary by batch and temperature, so run a small test tile before committing a project.
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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