In a cleaning device, a head of the device in which a brush is arranged, can get contaminated by particles and/or droplets picked up by the brush during one or more cleaning actions. In order to clean the head, the cleaning device is placed on a tray filled with an amount of cleaning liquid, and the cleaning device is operated for a period of time. During that time, the head is flushed with the cleaning liquid, where the brush serves for picking up the liquid from the tray and releasing the liquid in the direction of components of the head. The tray has an elevated portion, and the brush is positioned on that elevated portion to allow for gradual wetting of the brush.