Here are some - in German - regualations about interiors of ships and submarine.
From the General Regulations No. 31, March 1940 edition, regulation for applying paint to ships and vehicles of the Kriegsmarine D. Paints for submarines:
http://www.u-boote-online.de/dieboot...aerz_1940.html
From the General Regulations No. 31, July 1944 edition, regulation for the application of paint on ships and vehicles of the Kriegsmarine D. Paints for submarines:
http://www.u-boote-online.de/dieboot...juli_1944.html