Numerous written sources, such as personal letters from the artist to acquaintances and friends, diary entries, and invoices from paint manufacturers provide valuable insights into the practical and creative decisions Baumeister had to make during the war.

From these documents, we can learn about the reasons for choosing certain materials, their origin, and the difficulties encountered in obtaining them.

Letters document the daily challenges Baumeister faced, such as obtaining good-quality clothing and shoes. Historical invoices contain information indicating who supplied him with which materials.

These included artists' paints, such as the Mussini resin oil paints from Schmincke listed on this invoice. On the basis of such invoices, we can research what these materials consisted of in Baumeister's time, and try to find in manufacturers’ archives historical reference materials that can be analyzed.

Baumeister also ordered large quantities of a white "putty" (“Spachtelmasse”) and a colorless "Durapon topcoat" (“Durapon-Überzugslack”) from the Lechler company – materials that were not originally intended for use on easel paintings, but rather for house painting. Thus, written sources such as invoices contain important information. Sometimes, however, new questions arise when they are examined: For example, it is unclear what "special white" (“Spezialweiß”) and "special black" (“Spezialschwarz”) consisted of, what was so special about them, and whether we can find these materials in his paintings.

Image and audio sources

Baumeister's estate contains many photographs that show him at work and provide important insights into his working process. There is also a film which enables you to literally look over the artist's shoulder as he works. 

Discarded paintings 

As researchers, we are very fortunate to have access to paintings that Baumeister himself created, but which he rejected, because he was not satisfied with them. Although he did not treat them as original works, he kept them and specially marked them in various ways.

Palettes provide an intimate insight into the painting process: They reveal exactly how Baumeister mixed his colors. Two palettes from his final creative years have been preserved in his estate and can be compared with the materials used in his paintings.

Baumeister often used old cardboard boxes as palettes on which to mix his colors.

Tools such as brushes and metal combs provide a direct insight into how he applied his paints and worked them into the surface.

Historical material samples 

The artist's estate, the historical material collection of the ABK Stuttgart, and the archives of the artists’ paint manufacturers Schmincke (from Erkrath near Düsseldorf, Germany) and LUKAS (formerly called Fr. Schoenfeld) at the Conservation Center (RED) in Düsseldorf, contain historical tube paints, varnish bottles, and similar items that can provide crucial clues to the original composition of the painting materials used in the paintings. They are therefore important reference materials for our investigations of paintings.