A brittle material that breaks into highly dangerous sharp shards on impact isn’t the obvious choice to put on the front of a motor vehicle, so it’s no surprise that the earliest cars didn’t have windshields. However, before long top speeds were high enough to make them essential.
In those early days of dirt roads, windshield breakage was an everyday hazard and injuries could be severe. Even today, plate glass screens on veteran and vintage cars can be lethal: replacement with laminated glass is highly recommended if the car is driven.
Laminated glass was actually invented in Britain by John C Wood, who came up with a method of gluing a layer of celluloid between two sheets of glass, so that it would not separate on impact. Developed in 1905, his invention was called Triplex. In France, scientist Edouard Benedictus came up with a similar invention; while in the USA, Ford was first to use laminated glass, fitting it to all its cars from 1926.
The only disadvantage of early laminated glass was that the celluloid centre layer could discolour over time, leading to a tinted effect and even becoming opaque and separating; this is not uncommon on vintage cars.
Toughened glass came into use in the 1930s. Heat treatment hardens the glass, making it much more resistant to breakage and also causing it to break into small, smooth beads that do not cut the skin – though it is difficult to see through when shattered.
Laminated glass was the ultimate answer, however, and modern production techniques eventually brought the cost down until laminated windshields became the norm rather than the exception.
The influence of glass on car styling cannot be underestimated: until the mid-1950s, flat glass was usual and dramatically affected what stylists could achieve, many resorting to split windshields (Jaguar XK120, Morris Minor) to achieve better looks and aerodynamics. The first curved screen was fitted to the 1934 Chrysler Imperial Airflow, but cost prohibited its wider use at first. In Britain, the 1951 Ford Consul pioneered its use, Ford counting on the economies of mass production to cut costs. Double curvature was the next development and was popular on US-built cars by 1957, followed by curved side windows in the 1960s.
As glass area grew, heat from the sun became a problem and PPG introduced its first tinted glass, Solex, in 1952. Modern heat-reflective layers block 60% of the sun’s energy, reducing damage to trim.
Finding replacement glass for classic cars is not as hard, or as expensive, as you might think. Tucked away on the Isle of Sheppey is a remote division of Pilkington (itself now part of Nippon Sheet Glass) which makes an incredible range of laminated glass for classics.
‘We can do most classic ’screens,’ explains Peter Swann, who in 2000 persuaded Pilkington to give him a year to prove the Sheppey plant could be profitable rather than closing it and making all classic glass obsolete. ‘With some handbuilt cars there are different versions – we have five for Ferrari 275s – and we can make one-off, bespoke screens. Tooling costs add up, though, so it can cost $2600 for a complex screen such as a Group C racing car’s.’
Windshield replacement on older classics is generally fairly inexpensive, with ’screen and fitting costing as little as $260. Replacing later, bonded screens is a far more expensive procedure and repairing becomes a viable option for laminated screens, where the inner layer is undamaged. Small chips and tiny cracks can be ‘fixed’ with a clear glue that seeps in, fills the crack and strengthens it.
If you’re after toughened glass, or laminated for cars that are outside Pilkington’s range, the best answer in the UK is to contact Uroglas: ‘Most things are possible,’ says Uroglas’s Stuart Robertson. ‘Provided there’s a pattern, we can get almost anything made. Flat toughened glass is no problem, but curved usually requires a minimum of 25 for tooling to be viable. Curved door glass, however, being constant radius, can usually be cut from sheet.
‘Cost varies from around $50 for a flat toughened door window to $1300 -3000 for a curved laminated windshield, including tooling. What can be difficult to get made is glass with sharp curves at the extremes, such as some rear windows. Sometimes you can get glass made in laminated that you can’t get in toughened, but in applications where it may flex, such as tailgates, laminated may break.’
Uroglas also offers a big step forward for some classics, especially those used all year round or for winter rallying – heated windshields. These are available for everything from Mk1 Escorts to Astons and E-types, and some of the laminated heated rear screens of the 1960s, such as Mk2 Jaguars’, are available too.
Perspex windows have been a feature of competition cars for over 50 years but developments in plastics make them much more durable and clear now than in the past. Motor sport regulations now accept plastic windshields, provided they are no less than 4mm thick. Because they don’t shatter, plastic screens are more likely to repel fence posts etc from penetrating the car. Ironically, for road use, plastic windshields are not legal – though it would take an eagle-eyed MoT inspector to spot the difference.
Plastics4performance, among others, supplies screens for competition cars with excellent optical clarity, UV-resistant coatings to help prevent ageing, and abrasion-resistant coatings to reduce scratching from windshield wipers.
If you’re more interested in concours or preserving originality than in competition, it’s useful to know that most car glass is date coded.
In the USA, most glass came from Libby Owens Ford (LOF) and is coded with two letters, or two letters and a number, to the right of the LOF shield. The letters signify the month (first) and year the glass was made; the number is the day of the month. Year identifiers from 1963 to 1972 are C G J A Z X V T N Y and month identifiers from Jan to Dec are N X L G J I U T A Y C V.
In the UK, most glass on classics came from Triplex and is dated by dots above and below the letters of the logo. The year dot is below (or above) the word TOUGHENED or LAMINATED. The decade isn’t identified, so a dot on the T or L is 1951/’61/’71 etc, on the D is 1959/’69 etc and a dot after the D is 1960 etc.