The average person doesn't think much about glass unless he's cut himself on it or she is buying windows. There is a big difference in types of glass, though, and when you're buying windows, factors such as glass thickness, cost and ease of installation come into play. When considering plate versus tempered glass, there are a number of factors that may sway your decision, so learning about both is a wise move.
While most people assume that any non-stained glass is a varietal of plate glass, plate glass actually does refer to a specific sort of glass that has some distinctive characteristics. The name "plate glass" refers to the very first sort of truly flat glass that was created. Making plate glass required pouring molten glass onto flat plates or metal tables and rolling it until smooth and uniform. Then it was left to cool. Large sheets of glass for storefronts and shop windows were made this way, and the same technology was used to make mirrors. Although the plate glass process was replaced by the float glass method in the 1960s, people still tend to refer to a large flat pane of unstained glass as "plate glass."
Both float glass and plate glass can be engineered for exceptional quality and clarity and can be bent or curved in a variety of ways for decorative touches or as an integral part of an interior layout. Float glass can be made of varying degrees of thickness as well. Though plate glass has a clean, slick look, it can create problems when it breaks. Plate or float glass is what is called annealed glass. This means that it is left to cool on its own during the manufacturing process. When plate glass breaks or shatters, it typically divides into large, sharp shards that can be very dangerous to people, furniture or other property. For that reason, many businesses and public venues avoid plate glass in favor of sturdier options with less potential for damage after breakage. Shiny, clear and flat, plate glass is often used for its aesthetic appeal.
Tempered glass is around four times the strength of annealed glass. Tempered glass describes a glass that has been cooled rapidly during its manufacture. The process of tempering the glass actually alters the chemical compound of the glass, and when it breaks it shatters into small, blunt-edged pellets that are significantly less sharp than the large, dangerous shards that come from plate glass. This feature makes tempered glass useful in places like concert halls, public spaces, transit hubs and anywhere else that has heavy foot traffic and the potential for accidents. Tempered glass is also used in vehicle windows and very often in bath and shower enclosures, skylights and doors, and microwave ovens.
The process of tempering glass includes cutting it to the necessary size, heating it to more than 1,112 degrees Fahrenheit and then beginning a rapid cooling process known as quenching, which cools the outer surface of the glass. As the inner core cools it attempts to pull away from the surface, causing an inner tension. At the same time, the surface begins to compress giving the glass its strength. In addition to being a safer glass for public or high traffic areas, tempered glass also has significantly greater heat-retention properties than float glass, making it an economical choice for homes or business in cooler climates.
Ashley Friedman is a freelance writer with experience working in the home, design and interiors space.