The History of Sodium Fluoride

Sodium Fluoride: The by-product of Aluminum manufacturing

1885: Pure Aluminum was so rare at this time that it was considered to be a precious metal. Charles Martin Hall's method of processing the metal ore was to pass an electric current through a non-metallic conductor (molten sodium fluoride compound was used) to separate the very conductive Aluminum. In 1889, Charles Martin Hull was awarded U.S. patent #400,666 for his process.

In 1888, together with financier Alfred E. Hunt, Charles Martin Hall founded the Pittsburgh Reduction Company now know as the Aluminum Company of America (ALCOA).

By 1914, Charles Martin Hall had brought the cost of Aluminum down to 18 cents a pound and it was no longer considered a precious metal.

Reference: http://inventors.about.com/library/inventors/blaluminum.htm