Beginning of Essay
Spray cans produce an aerosol, the technical term for a very fine spray. They do this by means of a pressurized propellant, which is a liquid that boils at everyday temperatures. Inside the can, a layer of gaseous pressure increased, and eventually it becomes so h ....

Middle of Essay
.... the can, and by the coil spring directly below the valve stem. When the push button is pressed, it forces the valve stem down in its housing, uncovering a small a small hole which leads up through the stem to the nozzle in the button. This allows the product to be forced up the dip tube by the gas pressure in the can. The nozzle is shaped to give a spray or a continuous stream. To produce a fine mist, a propellant is used which mixes with the product. The two leave the nozzle together and the propellant evaporates a soon as it reaches the air, breaking the product in to tiny droplets. The same technique used with a more viscous liquid and a wider n ....