Manufaturers make glass stronger by mixing more iron into the silica. Glass can also be chemically strengthened, making it suitable for use as paving or flooring. Laminated or safety glass is also stronger than untreated material. For security purposes, there's little substitute for glass thickness, though manufacturers are striving to make glass lighter and more transparent. PVB is valued for its affordability and transparency, though many companies are working to develop new and stronger interlayers.
Laminated glass is used to resist storm damage, break-ins, bombings, and fire.
The addition of plastic layers to glass also reduces sound transmission. Bulletproof glass is usually made by adding layers of polycarbonate. New generations of bulletproof glass are designed to look like standard architectural glass. Low-e films boost the energy efficiency of glass by reflecting radiant heat. New spectrally selective coatings, now integrated into low-e films, increase the efficiency of glass by screening out certain types of soalr waves while maximizing daylight.