Aerosols are essentially fog. They’re water-based micro-drops suspended in a gas, which is usually air.
In 1926, Norwegian Erik Rotheim developed the first aerosol sprayer. Eventually, he applied for Norwegian and US patents and worked towards commercialization.
First, he worked towards aerosolizing paints and varnishes but customers showed no interest. Subsequently, he continued looking for commercial applications but died in 1938, at age 40.
Rotheim’s estate sold the patent to a US company where the technology lay largely dormant until the 1940s. Eventually, the military realized the usefulness of an aerosol bug spray during WWII, the “bug bomb.”
Rotheim used a pressurized gas that kept a steady pressure inside the can, releasing a set amount of liquid and gas. In 1949, American Robert Abplanalp invented the aerosol spray valve, that enabled aerosolization without a pressurized gas … the spray pump.
Aerosols became popular in the 1950s with countless uses. Women sprayed products in their hair, people painted with airbrushes, car finishes became smoother, window washing solutions sprayed evenly. Common uses include medicine, spraying pesticides and insecticides, and for fuel injection systems. These products are so common today it’s hard to fathom that the innovation is relatively recent.