Germany - Breweries

Zum Schlüssel (to the Key) Brewery is a brewery in Düsseldorf that was founded in 1850. It is the smallest of the four traditional Altbier breweries in Düsseldorf's old town.
In the mid 1990s the beer brand Gatzweilers Alt (Gatz) was sold off to the Carlsberg Group.
Some of the Brewery's Range
Gatzweilers Alt (Gatz) -
Schlüssel Alt -
-

Over the years the brand identity is updated and re-launched with subtle changes, a change of Logo or a new font.
Sometimes this brand update is done by the new owners after a brewery has been sold, other times just to give the brand a fresh new look on the ever growing market.

Below are some notes to help identify some of these changes and an aid to reference the year of the glass.