Plans have been scrubbed, after the owners spent $6-10M on development and samples, to use special prismatic glass panels for the lowest level of the new 1 World Trade Centre in New York City. However, a new glass design may be in the works. The design called for the construction of 13'14"x4" panels made of ultra-clear (low-iron) tempered glass that, once formed, would have had unique wedges cut into them to provide prism-like shimmering optical effects. After heat strengthening, several panels were to be laminated together and attached to an aluminum screen framework. Two thousand of the five-foot thick units would have been required. The panels were an aesthetic response to criticism that the first architectural concept for the base of the structure appeared to be a large concrete or stone bunker. It was hoped that the glass panels would provide a colourful and more inviting entry level. However, controversy plagued the idea from the start. When the glass panel amendment to the design was unveiled, a furore ensued when planners announced that the units, including their structural assemblies, would be made in China. Eventually, WTC officials awarded PPG a contract to make the glass using its Starphire composition, with Chinese companies and others doing the post glassmaking work. It appears that the problem with the panels was linked to glass-strengthening issues and that "the glass panels tended to bow after they were cut and tempered, which interfered with the lamination process. The ridges cut into the glass also proved to be too brittle and broke into large pieces, rather than tiny pellets." (NY Times online, May 11/2011). The Associated Press reports that the Port Authority of New York & New Jersey will substitute another type of glass, although there are no specifics to-date. The story added that the replacement glass will be of a type "more typically used in construction, but the design is still being finalised."
