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Secrets of Golden Aluminum Foil

2016-08-23

Do you know why is golden aluminum foil shiny on one side and not as much on the other? In what is called the Bayer Process, after pure molten aluminum is obtained from aluminum oxide, it is placed in furnaces with a small amount of other elements, thus typically, the final product will be between 99.8% and 99.9% aluminum. This liquid is then poured into chill casting devices where it cools into large slabs called "ingots". Next, the ingot will be treated with heat (annealed), and then rolled between heavy rollers.

This initial foil is sent through still more rollers, several times, until it reaches the desired thinness. For the type of foil that is bright on one side and matte on the other, it is so thin that during some of the last rollings, two sheets of the thin foil must be placed together lest they tear or crimp during the final rolling of the sheets.

One consequence of this is that while the sides that touch the highly polished rollers are burnished to a bright finish, the inner sides that touch the other golden aluminum foil remain matte.

As a matter of fact, before aluminum became cheap and readily available, during the last part of the 19th and early 20th centuries, a type of thin foil, used commercially, was actually made of tin (tin foil). Because of the popularity of this foil, today many people still call aluminum foil as tin foil.

More than just packaging, aluminum can also be used to polish silver. After lining a deep pan with foil, cover it with cold water and add a couple of teaspoons of salt and your silverware. Chemistry will remove the tarnish. A similar process can be used to clean jewelry, except exchange the cold water for hot, and the salt for a tablespoon of laundry detergent. Likewise, a sheet of golden aluminum foil underneath freshly polished silverware will deter tarnishing. Besides, scissors can be sharpened by cutting through several layers of golden aluminum foil a few times.

In practice, sixty-five percent of aluminum used all over the world is recycled, and this includes an average of 123,097 cans each minute. Most aluminum cans are made with at least 50% post-consumer recycled aluminum, and it takes about 90 days for the aluminum from a used can to be back on a store shelf. However, although golden aluminum foil can be recycled, most recyclers insist that it be cleaned in advance.