Mroz Farbenfilm was an additive two-color process introduced by Josef Mroz in 1931, in Vienna, Austria. The process employed red and green filters during filming, and, after processing, the frames of the film print were stained alternately red and green. Rooted in the principles established by William Friese Greene’s 35mm Biocolor process, Mroz’s innovation lay not in the process itself, but in its adaptation for the 9.5mm format, with the aim of making color filmmaking accessible to the amateur and home markets. The anticipated commercial success failed to materialize and Mroz Farbenfilm remained a Viennese phenomenon. This limited impact is evident in the fact that we only know of three surviving 9.5mm films using this method.

Josef Mroz (1893–1945), a trained cinematographer, established several companies in Vienna in the 1920s aimed at amateur enthusiasts, spanning from radio to photography, and, eventually, small-gauge film. Under the name Mroz-Farben-Foto, he manufactured a patented three-color photo camera, laying the groundwork for subsequent developments in Mroz Farbenfilm. As early as 1923, Mroz had entertained the idea of developing a color process not only for photography, but also for moving images. The newspaper Prager Tagblatt reported on his endeavors to discover naturally exposed colored film, rather than B/W film that required colorization. Undeterred by slow progress, Mroz expressed confidence in eventually achieving a breakthrough (Prager Tagblatt, 1923). In 1925, Mroz announced that he had successfully solved the technical issues, but that greater financial resources were still required for the practical implementation of color motion picture film (Die Stunde, 1925).      

It was not until November 1931 that Mroz introduced his color film process to the Viennese amateur film scene. Hugo Fleischer, an amateur filmmaker and the press spokesperson of the cine club Klub der Kinoamateure Österreichs (KdKÖ) attended the lecture. Fleischer wrote a comprehensive report on the process, titled “Der 9½-Farbenfilm ist da!” [“9.5 color film is here!”]. The report highlighted the novelty of color film specifically for the 9.5mm format, providing a more cost-effective alternative to the significantly more expensive Kodacolor on 16mm. Hugo Fleischer pointed out a limitation in the system: the absence of blues, which were unachievable in the additive two-color process. However, he also argued that the absence of blues was only slightly disturbing, and it would be up to the amateur to avoid filming radiant blue subjects (Fleischer, 1931).

Until 1931, 9.5mm filmmakers were confronted with limited availability of film stock, having only Pathé’s orthochromatic film stock at their disposal – a B/W film which was sensitive to green and blue light, but less sensitive to red. There was a growing demand for greater versatility, particularly a panchromatic film stock – B/W film, sensitive to a wider range of colors – allowing for more accurately represented and detailed B/W images. Although Perutz, Mimosa and Pathé all announced panchromatic film stock for the 9.5mm format during the late 1920s, no products were brought to market until the early 1930s (Der Kino-Amateur, 1931). Josef Mroz hoped to capitalize on the hiatus and supply color-sensitive film for 9.5mm filmmakers – at least in Vienna by custom-cutting 16mm panchromatic stock down to size. The June 1931 issue of Der Kino-Amateur, the cine club’s monthly magazine, informed KdKÖ members that Josef Mroz´s business now offered panchromatic 9.5mm film ( Der Kino-Amateur, 1931). The introduction of an alternative 9.5mm film stock was met with enthusiasm – despite occasional complaints about perforation misalignment, Mroz’s custom-cut 9.5mm film garnered interest and demand, even though the sales organization was not fully established and the product was not actively advertised (Fleischer, 1931: pp. 288–9). During 1931, this panchromatic film planted the seed for the realization of Mroz Farbenfilm, as it allowed for the capture of red light, a critical element in the additive color process. However, by 1935, Mroz Farbenfilm was no longer present in the company’s price lists – its decline likely due to a lack of demand alongside the introduction of subtractive film stocks such as Kodachrome and Agfacolor Neu.

The location of Mroz’s business had served as a photographic studio since 1881, situated in the courtyard of the Ägidihof, Gumpendorfer Straße 96, Vienna – it included an atelier and a photographic garden. In late 1927, Josef and Ida Mroz took over the photo studio, incorporating a small-gauge film lab. The premises served as a film lab until 2009 – establishing a pivotal place in Vienna’s analog film landscape for both amateur and independent filmmakers. It was by chance that in the company archives an original film by Josef Mroz was discovered — a demonstration film titled Testfilm from 1930, which is one of the three remaining films on Mroz Farbenfilm. The other two films that survive were created by Josip Slišković and Friedrich Apfelthaler, both of whom were within the KdKÖ cine club’s circle – they are preserved at the Austrian Film Museum,Vienna. 

Records document Josef Mroz’s close ties to Nazi ideology. Documents at the Federal Archive in Germany indicate that he became a member of the NSDAP as early as 1932. During the prohibition era, Mroz facilitated gatherings for party members in his business, capturing various National Socialist events on film and screening them for party members (Bundesarchiv Deutschland, 1938). Between 1943 and 1945, he participated in the Führerauftrag Monumentalmalerei (“The Führer’s Monumental Painting Assignment”), a campaign commissioned by Adolf Hitler to photograph endangered paintings and interiors of historical and artistic importance in color. Josef Mroz, along with his son Thaddäus, is mentioned in the roster of official color photographers (Fuhrmeister et al., 2006).