A printer cartridge is disclosed that is under negative pressure to retain liquid and allows controlled ingress of atmospheric air to release liquid from the printer cartridge. A labyrinth on a surface of the printer ink cartridge provides controlled ingress of atmospheric air having an entrance chamber to allow entry of atmospheric air, an exit chamber in communication with the liquid, and an elongate channel extending between the entrance chamber and the exit chamber. The elongate channel having a raised track formed on the surface and extending along each side of the elongate channel.