Uploaded October 2012 | Updated September 2026, 13 hours ago
Safety glass testing standards were published in the 1930s. The impact test consisted of dropping a half-pound steel ball bearing onto a sheet of glass approximately 12" square, from a height of 10 feet. This is a "hard" body test. Laminated glass could crack when tested, but in 3 tests out of 5 the steel ball could not pass through the glass. Heat-treated glass could not crack in 3 out of 5 tests. The successful test specimens were then impacted by raising the drop height of the steel ball in 12 inch increments, until the ball did penetrate the specimen. This 1936 safety glass Standard was written for automotive applications, presumably to reflect the risk associated with "hard" body stones impacting a car windshield, an example discussed in my Introduction. Similar impact tests still exist in the automotive industry. A second impact test in the 1936 Standard dropped a leather bag filled with eleven pounds of shot, four feet, "to observe the behavior of glass when subjected to impact from a large object". This test may very well have been developed to simulate the effect of a person's head impacting the windshield, in an accident.Safety glass is a stronger, safer version of ordinary glass. It is often used in locations where human harm due to breakage is likely, such as cars and low windows. It is found in two forms - laminated safety glass, commonly found in car windshields and tempered safety glass which fractures parallel to its edge rather than perpendicular, and when it shatters, it breaks into small, rounded, generally safe pieces. This clip is taken from the 1937 silent film from the US Bureau of Mines and the Ford Motor Company. The film shows how sand rock and silica sand were quarried, dried, and shipped to a glass plant, where they were melted and made into sheets of glass. To make the safety glass, cellulose acetate is placed between sheets of glass and, after various processes, safety glass is produced. The entire film is available at the US National Archive in College Park, Maryland.
Safety glass testing standards were published in the 1930s. The impact test consisted of dropping a half-pound steel ball bearing onto a sheet of glass approximately 12" square, from a height of 10 feet. This is a "hard" body test. Laminated glass could crack when tested, but in 3 tests out of 5 the steel ball could not pass through the glass. Heat-treated glass could not crack in 3 out of 5 tests. The successful test specimens were then impacted by raising the drop height of the steel ball in 12 inch increments, until the ball did penetrate the specimen. This 1936 safety glass Standard was written for automotive applications, presumably to reflect the risk associated with "hard" body stones impacting a car windshield, an example discussed in my Introduction. Similar impact tests still exist in the automotive industry. A second impact test in the 1936 Standard dropped a leather bag filled with eleven pounds of shot, four feet, "to observe the behavior of glass when subjected to impact from a large object". This test may very well have been developed to simulate the effect of a person's head impacting the windshield, in an accident.Safety glass is a stronger, safer version of ordinary glass. It is often used in locations where human harm due to breakage is likely, such as cars and low windows. It is found in two forms - laminated safety glass, commonly found in car windshields and tempered safety glass which fractures parallel to its edge rather than perpendicular, and when it shatters, it breaks into small, rounded, generally safe pieces. This clip is taken from the 1937 silent film from the US Bureau of Mines and the Ford Motor Company. The film shows how sand rock and silica sand were quarried, dried, and shipped to a glass plant, where they were melted and made into sheets of glass. To make the safety glass, cellulose acetate is placed between sheets of glass and, after various processes, safety glass is produced. The entire film is available at the US National Archive in College Park, Maryland.
