First cars made their appearance in 1885. By 1905 they were, or looked like open carriages whose passengers were protecting themselves using goggles, heavy clothing and leather helmets. When manufacturers developed their vehicles allowing them to reach "breakneck" speeds such as 30 or 40 km/h the need for protection placed the first windshield in front of the passengers.
It was a small flat rectangular glass panel so dangerous when broken that many people faced phobia to ride in a car. The problem was solved by an accidental discovery. In 1905 in France, chemist Edward Benedictus was experimenting with a substance called Nitrocellulose. He dropped a test tube which, to his surprise, did not fall apart although it was shattered.
A soft transparent film was holding the glass fragments together. At the same time in England, inventor John C.Woop joined two flat glass panels using cellulose and created the first safety windshield, naming his company Triplex and the glass Laminated.
It was Henry Ford that first applied the new invention to his cars and by 1928 cars were equipped with Laminated front, rear and door glass panels. There was only one drawback. In case of an accident it was hard for the passengers to get out through the windows.
In the 50s a new discovery solved this problem. A flat glass panel heated to high temperatures in a tempering oven followed by immediate quenching, becomes almost ten times stronger and when broken, it shatters into small harmless pieces.
Its name is Tempered or Toughened. So far, the only significant progress in these discoveries was the replacement of Cellulose film by Polyvinyl Butyral [PVB] film, which is much more powerful and totally transparent.
There was however a major change in the fitting method. Fitting using a rubber seal [rubber] became obsolete first in the US in the 1950s and later in Europe in the 1980s and currently almost all vehicles [passenger, trucks, buses, trains etc.] are equipped with adhesive bonded glass panels.
Bonded glass technology offered several solutions to car designers:
- The significant increase in passive safety due to the use of "adhesive bonded windshields" allowed a reduction of body metal parts resulting in an increase in performance and fuel efficiency.
- Significant reduction in air drag and turbulence noise.
- Fixed points for the activation and fixing of the airbags are some of the advantages. All these however, turned adhesive bonded glass panel replacement into a highly specialised work that should be treated as seriously as car roof, or door sill, or cabin part replacement.
In addition, the increasing use of plastic, or aluminium in modern car manufacturing, requires expertise and high standards materials [polyurethane adhesives, primer, activators etc.] to avoid altering vehicle body structure and to ensure proper operation of the vehicle electronic and safety systems [airbags].