Innovative Glassmaking Techniques

The Industrial Revolution came and in the span of just two centuries window technology traveled through light years, so to speak, with major implications for architecture. The production of flat glass by breaking and spinning a blown globe gave way to the glass cylinder, blown by using compressed air, which could be slit lengthwise, reheated, and allowed to flatten on an iron table under its own weight. Although the natural fire finish was destroyed on one surface the final product, still far from being truly flat, was flatter than crown glass. Output increased dramatically. By mid 1800s the world was astonished by the design of the Crystal Palace in London, made with 300,000 sheets of cylinder-blown glass set on a lightweight iron framework, a building that is often considered a precursor of the modern movement.

Fundamental to the great increase in glass output was the introduction of the regenerative furnace. Higher temperatures sped up melting times.

The conversion of the old siege floor into a vast tank into which the materials directly flowed allowed the continuous production of molten glass. Windows and window frames were still crafted by hand, but with increased glass production, they became available to a much broader segment of the population.

The late 1800s marked a time of rapid change in domestic architectural styles - some regionally based, some revivalist styles borrowed from Europe, and others more esoteric American inventions. It's fair to say, however, that the window was not a major determining influence in the design of a house. Whether articulated in the language of Beaux Arts, Queen Ann, Tudor, or Craftsman, punched openings in the masonry or timber-framed facades provided minimal visual exposure or ventilation from exterior to the inside and were primarily part of the artistic language. In certain areas, there was a tendency to employ regionally appropriate designs, tall windows that encourages natural ventilation in the south (the French Colonial) and thick walls of adobe, flat roofs, and minor window fenestration in the southwest (the Spanish Colonial) to protect from the intense sun.

Window fenestration on commercial buildings followed that of residential structures, with relatively small punched holes conforming to the overall stylistic architectural expression. Windows were operable, providing natural ventilation and often set deep in the façade and separated by thick piers, a style which characterizes Richardsonian buildings of that era. In the mid to late 19th century, commercial buildings with cast-iron facades presaged curtain-wall construction, and also much of the theory of skyscraper design. While still containing separate window units, these facades whet the appetite for a continuous glassy surface.

Curtain-wall construction, however, wasn't possible until after 1905, when a Belgian named Fourcault managed to vertically draw a continuous sheet of glass of a consistent width from the tank. Commercial production of sheet glass using this method commenced in 1914. Colburn refined this process, with the support of Libbey-Owens in 1917. The Pittsburgh Plate Glass Company (now PPG) updated the process's main features and it was used from 1928 until the company changed to the float glass manufacturing process decades later.

In 1909, the world saw the first example of steel mullioned, strip-windows and uninterrupted steel spandrel façade in the Boley Building in Kansas City. Designed by Louis S. Curtiss, its walls were enclosed by continuous bands of glass, accented slightly by glazed doors, above painted steel spandrel strips.

One other remarkably advanced buildings of its time still stands in San Francisco as a monument to the use of boldly scaled glass. The seven-story Hallidie Building (1917-1918), designed by Willis Polk, is all glass with the exception of four fanciful bands of superimposed cast-iron decoration and fire escapes.

The vanguard of the International Style was emboldened by these advances in window technology. Ludwig Mies van der Rohe, Philip Johnson, Richard Neutra, and others gained prominence in their commercial work by using great expanses of glass to announce that a building's structure no longer needed to be displayed in the building's exterior facade. Then they seized the opportunity to test their modernist theories at the residential scale, creating three-dimensional tributes to the invention of plate glass. In 1938, Richard Neutra designed the "windshield" house for a wealthy family on Fishers Island, New York. Huge sheets of plate glass in metal frames gave the owners sweeping panoramic views.

The Modernist aesthetic of immense slick glass architectural surfaces could filter into the public domain most rapidly with new technology. It was the float process developed after the Second World War by Britain's Pilkington Brothers Ltd. and introduced in 1959 that combined the brilliant finish of sheet glass with the optical qualities of plate glass. Molten glass, when poured across the surface of a bath of molten tin, spreads and flattens before being drawn horizontally in a continuous ribbon into the annealing lehr. The post-war residential building boom brought a newfound consumer interest in the "picture window." Homeowners not only liked the modern style, but also the views and daylight the large windows afforded.