WINDOW TECHNOLOGIES: Surface Treatments
Ceramic frit paint is comprised of minute glass particles, pigment, and a medium to mix the glass and pigment together. The paint is applied to one side of the glass—either heat-strengthened or fully tempered to prevent glass breakage due to thermal stresses under sunlit applications—and is fired in a tempering furnace to create a permanent coating. For an insulating glass unit, the silk screen pattern is ideally located within the sealed cavity for protection. Frit can also be applied to laminated glass units. A low-E coating can be placed on top of the frit. To reduce long-wave radiative heat gains, it is best to use the fritted layer on the interior surface of the exterior pane of an insulating glass unit.
White ceramic frit has been the predominant color, however, dark ceramic frits, such as neutral gray, black, and silver metallic are increasingly utilized. These colors also help reduce reflection and offer alternative design options without adversely affecting performance. Frit location—or multiple frit combinations—within a glazing assembly affect such factors as solar absorption, shading coefficient, and appearance.
The design flexibility—in terms of pattern and color—of fritted glass is appealing, but many manufacturers also offer standard patterns, such as dots, lines, and holes. Pattern coverage is specified, most often in the 40 to 60% range, with density naturally impacting glass performance characteristics and vision area. In practice, the SHGC of a frit coating is affected by its color and location in the window assembly.
Acid-Etched and Sandblasted Glass