Thin Films on Float Glass: The Extraordinary Possibilities

Beginning in the late 1950s, and up to present time, the continuous float process has become, worldwide, the preferred method of flat glass manufacture. For almost all architectural and vehicular uses, the glass ribbon is made within a narrow range of soda−lime−silica composition. For centuries up to the 20th, flat glass had been made commercially by batch processes. Thereafter, prefloat continuous processes were introduced either to draw fire-polished sheets upward in ambient air or to draw glass horizontally through rollers, followed by grinding and polishing of both rough surfaces. Respectively, these were sheet and polished plate glass. However, despite the significant glassmaking changes, the flat glass article itself remained an essentially undifferentiated window to the untrained user. There were, of course, improvements in bulk quality and distortion over time, as well as cost gains and new body tints. Beginning with the late 1960s, new thin film technologies were applied to change the surface properties of float glass, and the article started to emerge as a more complex and extraordinary material. This memorial review is about two technologies that drove this and two others that are evolving.