what's inside a spray can
With less pressure, it can begin to boil. Particles break free, forming a gas layer at the top of the can. This pressurized gas layer pushes the liquid product, as well as some of the liquid propellant, up the tube to the nozzle. Some cans, such as spray-paint cans, have a ball bearing inside. If you shake the can, the rattling ball bearing helps to mix up the propellant and the product, so the product is pushed out in a fine mist. When the liquid flows through the nozzle, the propellant rapidly expands into gas.