Most of the documentary material at the INDOK Centre is classified as archival material due to its content, age and uniqueness. Its storage in physical form complies with the legal principles of preservation and usability, durability, integrity, accessibility, and the principle of protecting archival materials as cultural monuments (Protection of Documents and Archives and Archival Institutions Act, Official Gazette of the Republic of Slovenia, No 30/2006).
Archival material is kept in special rooms protected against mechanical damage, dust and soiling, light and sudden changes in temperature and relative humidity (RH). The material is divided into several collections, which dictate the choice of equipment of the archival room: everything is made of stainless steel with a calcined protective layer.
The photograph collection consists of negatives, diapositives, positives from the archives of the Vienna Central Commission, and some original older photographs without corresponding negatives. The negatives are black and white; gelatine negatives on glass plates and negatives on flexible carriers (cellulose nitrate and acetate and polyester films) are kept separately. Each negative is protected by a photo-activity tested (PAT) paper envelope and kept in a drawer; glass plates are additionally placed in cartons of non-bleached cardboard. Diapositives are kept separately from negatives; the primary packaging of medium-size colour diapositives (6 x 6, 6 x 7 cm) and Leica format is plastic, without polyvinylchloride or plasticisers. Positives are kept in archival boxes, similarly to conventional archives, except that they lie flat on shelves of movable cases. Archival material from the plan collection (e.g. original technical plans, watercolours, maps) is protected with folders and stored flat in dedicated drawers.
The temperature (18°C) and RH (40%) stability of the archives is provided by airconditioning controlled by air humidity and temperature sensors.
The documentary material at the INDOK Centre is publicly available (every working day between 9 a.m. and noon, and on Wednesdays also in the afternoon); approximately 200 additional extensive requests for material inquiries are met for users each year.