-Like olive amber discussed earlier, "old" amber is a color that is very uncommon in bottles made after 1890.
-In a related vein, when machine-made bottles dominated in the 1920s and glass making chemistry and techniques refined, amber became of a fairly standard tone and density. That is, the off color ambers like yellow, yellow amber, and black amber (so dark that light hardly penetrates) become increasingly uncommon and a medium to medium dark amber - like the bottle pictured to the left - became the dominate amber shade. The pictured machine-made beer bottle was produced by the American Bottle Company (Chicago, IL.) in the 1910s (Lockhart 2004).
-Amber was and still is the most common color for beer bottles as it provides the best light protection from the light wavelengths that are responsible for most photochemical reactions. Too much light (natural or artificial) causes beer to become "light struck" which is a distinctive "skunky" off-flavor which is associated with green and clear bottled beer (Papazian 1991,1994). Both of these latter colors provide little protection from the particular part of the spectrum which induce the off-flavor chemical reactions whereas amber glass provides a high level of protection (Dillon 1958).