A color system of a rotary printing press includes a doctor blade device with a doctor blade chamber containing ink for a printing process, an ink reservoir from which ink is supplied to the doctor blade chamber, and a supply system which allows ink to be supplied inside the color system. The color system is connected to a storage reservoir into which ink from the color system is introduced, to a solvent reservoir containing solvent for cleaning the color system, and to a refuse container into which ink soiled by the solvent is introduced. The supply system cleans the color system by automatically pumping off ink to the storage reservoir, and automatically cleaning with the solvent, by collecting the ink in the ink reservoir and supplying the solvent to the refuse container.