Yes! An aerosol is composed of a gaseous propellant and a liquid portion. An aerosol functions when the propellant forces the liquid out of the can. If there is no propellant, there is nothing to “activate” the aerosol. When a WD-40 can is held upright, the propellant is at the top, and the liquid at the bottom of the can. The inner dip tube extends down into the fluid. There is also a small opening (a tap hole) at the very bottom of the valve. In the valve is a small ball bearing. When the can is in the upright position, the ball bearing blocks the path to the small hole in the valve. This way, the only exit is through the bottom of the dip tube, which lets out only the liquid product. When the can is held upside down, the positions of the propellant and liquid are reversed. But in this position, the ball bearing blocks the path to the bottom of the dip tube, and the opening at the bottom of the valve, in contact with the liquid, is now open. The worst position to hold a can of WD-40® is sideways. Here the ball bearing blocks neither hole, and you lose propellant and liquid together. When all the propellant is gone, the aerosol will no longer function.