The founding of Dennert & Pape began in Hamburg ( present - day Germany ) in 1862. In that year, Johann Christian Dennert ( 1829 - 1920 ) bought a workshop for geodetic and mathematical instruments, especially theodolites, levelling instruments and planimeters, from his Master Mechanic Carl C. Plath.
In 1869, he moved his production to the then Prussian Altona in order to obtain government contracts for the land surveying of Schleswig - Holstein as well as the former Kingdom of Hanover. Due to the Franco - Prussian War ( 1870 - 1871 ), a gap in the market arose in 1872 as a result of the decline in imports of French slide rules, which Johann Dennert used to offer slide rules made of boxwood for the first time. However, these were replaced in 1888 by mahogany scales with celluloid veneer.
The trademark DUPA was introduced for all Dennert & Pape products in 1924. It was not until 1936 that production was switched from celluloid to the newly developed plastic Astralon, a mixed polimerisate that is particularly dimensionally stable and insensitive to moisture. These new slide rules were sold under the trademark Aristo, which was incorporated into the company name after the Second World War. Due to the war, parts of the production were relocated to Bludenz ( Vorarlberg, Austria ) in 1943. The establishment of a production facility in Austria began.
Between 1945 and 1948, the company was placed under public administration. After long negotiations with the Austrian Ministry of Finance, the former owners bought back the company in Hamburg in 1961. The company moved into new premises in Wörgl ( Tyrol, Austria ).
From 1956, both the parent company in Hamburg and the subsidiaries traded under the name Dennert & Pape Aristo - Werke KG. Due to the lack of a successor, Aristo in Hamburg, including its Austrian subsidiary, was taken over by Rotring in 1976. Finally, in 1998, the Wörgl production site - then Aristo - Rotring GmbH - together with the German Rotring went to the American group Sanford ( renamed Newell Custom Writing Instruments in 2019, owned by Newell Brands Inc. since 1992 ).
In 2003, Aristo products were distributed by the newly founded Geotec Zeichen - und Kunststofftechnik GmbH in Wörgl. The company was reorganised into the two companies Geotec Schul - und Bürowaren GmbH and Geotec Zeichen - und Kunststofftechnik GmbH in 2016. The two companies are now responsible for the production of drawing instruments and the entire area of plastics technology.
( source : Wikipedia )