This paper presents experiments done in order to build a functional OCR model for the Unified Northern Alphabet. This writing system was used between 1931 and 1937 for 16 (Uralic and non-Uralic) minority languages spoken in the Soviet Union. The character accuracy of the developed model reaches more than 98% and clearly shows cross-linguistic applicability. The tests described here therefore also include general guidelines for the amount of training data needed to boot-strap an OCR system under similar conditions.