What makes it spray?
Aerosols
The paint is mixed with a solution of propellant, much the same as you would mix paint and thinner. The propellant creates a pressure of about 80 P.S.I., at room temperature, by creating a vapour in the head space of the container. As the product is used, the head space increases, creating more vapour and thus giving a constant pressure down to the last ounce of product. The paint product is filled into the aerosol can, and the can is placed under a pressure loader where the propellant is injected through the valve.