Steel Blue Opal Frit (146)
Copper bearing glass that reacts with sulfur glasses. Steel Blue can turn the color of silver steel in the kiln. At tack fusing temperatures, the surface frequently develops a metallic gray film. This usually disappears at full fusing temperatures. To maintain the metallic effect, fire as quickly and low as possible.
At a full fuse, Steel Blue Opalescent has the potential to deposit trace amounts of copper on the surface of the kilnshelf. These deposits may react with sulfur-bearing glasses in subsequent firings. Processes that require greater heatwork, such as pattern or flow bar techniques, can also lead to copper deposits. Such deposits may not be visible and can react even when the shelf has been properly scraped and reprimed or, alternatively, when used ThinFire has been removed and new ThinFire is applied. This type of contamination is impermanent and may be burned out/fired out over the course of subsequent firings. A contaminated shelf can be fired with glasses—other than sulfur-bearing glasses—and no reaction will take place.
Reaction Chart: Download PDF