SSAF Window Films Ltd

Float Glass – Invention and Production

The worlds most common glass…

Sir Alistair Pilkington was washing up sometime in the late 1950’s when he noticed a plate floating on the soapy water, how did he get from there to a Knighthood in 1970?

The answer is the ‘Float’ method of glass manufacture, although it took many years to get from a floating plate to profitable production. The costs involved in developing this glass production technique almost bankrupted his employers, and when the invention was made public in 1959, it wasnt until around 1963 that it turned profitable.

The finacial risk paid-off for the Pilkington brothers, (Alistair Pilkington was no relation to the Pilkington brothers), Alistair had joined them as a technical officer in 1947 after a stint in Crete during the second world war. By the mid 1980’s it is estimated that the income from licensing and technical fees had reached £30million pounds a year!.

The Pilkington brothers were also the innovators of some of the plate glass polishing processes already in use, but Alistair had seen the need for less wasteful, more economical method of manufacture. A method which could also deliver a higher quality glass for the likes of mirrors, shopfronts and car windscreens, applications were distortion-free glass was necessary.

The process that Sir Alistair Pilkington invented involved floating a continuous ribbon of glass out of the melting furnace and along a ‘bath’ of molten tin. The glass is held at a high enough temperature for the irregularities to melt-out or burn-off, and because the surface of the molten tin is flat the glass is also created flat.

Towards the end of the production line the glass has cooled enough to be lifted away without the rollers marking it, and so, a glass is produced with a uniform thickness and a hard, bright, and almost polished surface.

The first licence was awarded to ‘The Pittsburgh Plate Glass Company’ in the early 1960’s, and now this float glass system is licenced to around thirty-five companys in twenty-nine countries. The Pilkington Group have fourteen plants around the world, (North America, Great Britain, Germany, Sweden and South Africa), and they currently supply 20% of the worlds spectacle lenses, and one in five of the worlds cars use pilkington glass.