This series contains writings by Bluemner which he called "Painting Diaries" and "Theory Diaries". All of the diaries dated after 1918 are unbound and consist of loose pages of notes which were often compiled by Bluemner into "diaries" at a later date. Diaries contain very little discussion Bluemner's everyday life. Portions of the diaries are written in German.

The Painting Diaries generally contain notes on Bluemner's newly-finished paintings or current work. The notes are illustrated and include technical discussions of his work. Bluemner's Theory Diaries include notes on art theory, such as color, form, line, and space. Many are illustrated in color. They address what he referred to as the painting "problem." The Theory Diaries date only from 1919 to 1925. Additional similar writings dating after 1925 are found in Series 4: Writings & Notes.

Diaries are arranged chronologically. Most of the diaries are preceded by a large manilla envelope, originally containing the diary, on which Bluemner wrote the subject of the diary, dates, and additional notes. Some of the envelopes were separated at an earlier date and are not matched to any particular diary. Portions of the diaries are not numbered and every attempt has been made to keep the pages in Bluemner's original order. Additional writings are found in Series 4: Writings & Notes. The diaries have been separated because of their special designation by Bluemner. In reality, there is little difference between the "diaries" and some of the additional writings in the other series.

This series has been scanned in its entirety.