Dull Or Shiny?

The date of Charles and Julia Hall’s first production of aluminium by electrolysis, February 23, 1886, was significant because in France, Paul Héroult, using the same process to produce aluminium, was quicker off the mark in applying for a patent. When Hall applied for his patent on July 9, 1896, he was sued by Héroult for infringement of the patent granted him on April 23, 1886. Thanks in part to Julia’s testimony, Hall demonstrated to the court’s satisfaction that he had a prior claim.

With a patented process that produced aluminium cheaply and in large quantities, Hall established the Pittsburgh Aluminum Company, later to become Alcoa, which by 1890 was daily producing 250 kilogrammes of the metal. He bequeathed to Alcoa on his death in December 1914 what they regard as their crown jewels, a chest holding the small aluminium pellets produced from his first successful experiment.

The possibilities offered by this lighter, more flexible metal were quickly recognised by inventors and design pioneers. Le Migron, commissioned by Alfred Nobel in 1891, was the first passenger ship with an aluminium hull, while the Hartford Railway Company produced lightweight railway carriages with aluminium seats in 1894. Karl Benz exhibited the first sports car with an aluminium body in Berlin in 1899 and the Wright brothers finally got off the ground with an engine containing aluminium parts.

Manufacturers of household goods also caught the aluminium bug. In 1893 the first mass-produced aluminium kettles were marketed, soon to be followed by frying pans and saucepans, which were lighter and warmed up and cooled down more quickly than their copper and cast-iron predecessors. Aluminium was also seen as a possible alternative to tin foil which, although it had been used since the 18th century to wrap food in while cooking, was expensive to manufacture, rather stiff, and left a bitter, metallic taste.

Robert Victor Neher’s invention of a continuous rolling process to produce thin strips of aluminium foil encouraged him to open the world’s first aluminium rolling plant in the Swiss town of Kreuzlingen in 1910. Bern-based chocolate manufacturer, Tobler, was an early adopter, wrapping their confectionary, including the distinctive triangular Toblerone, in aluminium foil from 1911. Maggi followed suit, using it the next year to package soups and stock cubes.

Aluminium foil soon demonstrated its superiority. It was a much more effective conductor of heat and electricity than tin foil, able to withstand very high temperatures, thus preventing foodstuffs from drying out in the oven. Once the food had been cooked, foil extended its life by offering an effective barrier against light, oxygen, and moisture.

Outside the kitchen it is used by pharmaceutical companies to package drugs and by food manufacturers to produce aseptic packaging which allows perishable goods to be stored without refrigeration. By the mid-20th century aluminium foil, of which Britain is one the largest consumers in the world, had almost completely replaced tin, although, confusingly, it is sometimes still called tin foil.

One of aluminium foil’s most distinctive visual features is a consequence of its manufacturing process. To meet the standards of ISO 7271:2011, the sheets must be between 0.006 and 0.2 millimetres thick and are milled in layers, a process which involves the application of heat and tension to stretch the foil to the required thickness. As a single strip is likely to break during the process, two layers are milled together and then separated.

Where the sides of the two layers have been in contact with each other they develop a matt or dull finish while the outer layers retain a gloss or shiny appearance. However, the performance of the foil is the same, irrespective of which side forms the outside of the wrapping. It seems it is simply a question of aesthetics. When it comes to non-stick foil, though, only one side is treated with the non-stick coating and food must be placed on the side marked “non-stick”.

In future, I will wrap my food in foil to reflect my disposition; shiny side out if I am happy and dull side out if I am down. You never know, it might catch on.


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