Ikigai Daily
Menu
WonderMaterials manufacturing fact

Float glass, the flat glass in almost every modern window, is made by pouring molten glass onto a bath of molten tin. The glass spreads into an even sheet with smooth faces that need no grinding or polishing.

St Helens, England, 1959

EngineeringTechnologyDesignBusiness

The story behind the card

Before float glass, large clear sheets were made as plate glass: cast or rolled, then ground and polished on both sides, a slow and costly job. Alastair Pilkington and Kenneth Bickerstaff of Pilkington Brothers developed the new method at the firm's works in St Helens, Lancashire, between 1953 and 1957. It works because glass is lighter than tin and does not mix with it: floating on the molten metal, the glass flattens under gravity and surface tension, then cools slowly as a continuous ribbon. The company announced the process in 1959, reached profitable full-scale sales in 1960 and licensed it around the world during the 1960s, when it replaced the older methods.

Türkçe oku
Bugün neredeyse her pencerede kullanılan float cam, erimiş camın erimiş kalay banyosunun üzerine dökülmesiyle üretilir. Cam kalayın üzerinde yayılarak düzgün bir levhaya dönüşür; yüzeyleri taşlamaya ya da cilaya gerek kalmadan pürüzsüz çıkar.
St Helens, İngiltere, 1959

Float camdan önce büyük ve saydam levhalar döküm camı olarak üretilirdi: cam dökülür ya da haddelenir, sonra iki yüzü de taşlanıp cilalanırdı; bu yavaş ve pahalı bir işti. Pilkington Brothers şirketinden Alastair Pilkington ile Kenneth Bickerstaff yeni yöntemi 1953–1957 arasında şirketin İngiltere'deki St Helens fabrikasında geliştirdi. Yöntem, camın kalaydan hafif olmasına ve onunla karışmamasına dayanır: erimiş metalin üzerinde yüzen cam, yerçekimi ve yüzey gerilimiyle kendiliğinden düzleşir, ardından kesintisiz bir şerit hâlinde yavaş yavaş soğutulur. Şirket yöntemi 1959'da duyurdu, 1960'ta kârlı seri satışa geçti ve 1960'lar boyunca lisans vererek bütün dünyaya yaydı; float cam kısa sürede eski yöntemlerin yerini aldı.

Sources and further reading

Background reading: Float glass
Get the mobile appAbout our cards

Related cards

These cards share a subject or reading mode with the card above.

WonderDesign

Cut an A4 sheet in half across its length and you get two A5 sheets with exactly the same proportions. This works because the international paper standard ISO 216 sets the sides in a ratio of 1 to the square root of 2, about 1 to 1.414.

The idea is old. The German scientist Georg Christoph Lichtenberg pointed out the advantages of the square-root-of-two ratio in a letter in 1786, and revolutionary France listed similar formats in a tax law of 1798. The modern system came from the German engineer Walter Porstmann, whose proposal became the German standard DIN 476 in the early 1920s and later the international standard ISO 216. The largest size, A0, has an area of one square metre; A1 is half of it, A2 half again, and so on down to A4 and beyond. Because every size has the same shape, a page can be enlarged or reduced on a photocopier without cropping. The main countries that still mostly use other sizes, such as Letter, are the United States and Canada.

ISO 216Read card
DriveDesign

A plug that fits only one way cannot be put in wrongly. Designing products and processes so that mistakes are impossible, or noticed at once, is called poka-yoke, Japanese for “mistake-proofing”.

The Japanese engineer Shigeo Shingo, who advised Toyota, developed the idea in the 1960s. In one factory, workers assembling a small switch sometimes forgot to fit one of its two springs. Shingo had them first put both springs in a small dish, then fit them from the dish; if a spring was left over, the mistake was obvious at once. He first called the method baka-yoke, “fool-proofing”, but changed it to poka-yoke, from poka, an inadvertent mistake, and yokeru, to avoid, because the old word seemed insulting to workers. Everyday examples include a memory card that goes in only one way and a microwave that stops when its door opens. Shingo argued that preventing a defect costs far less than finding it later.

Poka-yokeRead card
DriveTechnology

A QR code, the black-and-white square your phone scans, was invented in Japan in 1994 to track car parts in factories.

Masahiro Hara led the small team at the Japanese car-parts company Denso Wave that created the QR code. An ordinary barcode held only about 20 characters, and workers had to scan several of them on each box of parts, so the team wanted a code that held far more and could be read quickly from any angle. Hara has said the grid of black and white squares was inspired by the stones on a Go board. The three large squares in the corners use a pattern of black and white bands chosen because it almost never appears in print, so a scanner can find the code instantly and tell which way up it is. Denso Wave chose not to enforce its patent for standard codes, so anyone could use them, and phone cameras later carried them onto menus, tickets and payment screens.

DENSO WAVERead card
WonderTrade

Shipping containers, steel boxes built to standard sizes, let cargo move from ship to lorry to train without being unpacked. Since the first container voyage in 1956, they have cut loading costs so sharply that they helped create today's global trade.

Before containers, dockworkers loaded ships one sack, crate and barrel at a time, and loading a ship could take days or weeks. The American trucking entrepreneur Malcolm McLean changed that. On 26 April 1956 his converted tanker Ideal X sailed from Newark to Houston with 58 containers on deck. McLean calculated that loading cost about 16 cents a ton, against almost six dollars for cargo loaded piece by piece. International standards for container sizes and corner fittings followed in 1968–1970, so any box could fit any crane, ship or lorry. Ports changed, many dockworkers lost their jobs, and making goods far from where they are sold became cheap.

ContainerizationRead card
DriveBiography

Fazlur Rahman Khan, a Bangladeshi-American structural engineer, made very tall buildings cheaper to build with his 'tube' systems, in which a tower's outer walls work together to resist the wind. They shaped Chicago's John Hancock Center and the Sears Tower, now Willis Tower.

Before Khan, most skyscrapers relied on a rigid internal frame of steel columns and beams, and the taller they went, the more steel they needed to keep them from swaying in the wind. In Khan's framed tube, columns are set close together around the outside of the building and tied by deep beams called spandrels, so the whole outer wall acts like one stiff, hollow tube anchored in the ground. Working at the Chicago firm Skidmore, Owings & Merrill, he developed variations: the John Hancock Center (1969) braces its tube with giant diagonal X-shapes, and the Sears Tower (1973) bundles nine tubes together. Khan was born in Dhaka in 1929 and died in 1982.

Fazlur Rahman KhanRead card
Next card in the archiveThe Bessemer process, patented by Henry Bessemer in 1856, made steel by blowing air through molten iron to burn off excess carbon and other impurities. It made steel cheap enough to build railways, bridges and ships.Read next →