We are almost conditioned to shaking aerosol canisters before we spray them, right? It doesn’t matter if it is paint or anything else. The habit has become so natural that even when we pick up a canister of compressed air for cleaning a keyboard, we tend to shake the can. We do this even when the can has a clear warning stating, ‘Do Not Shake’! Is this habit of our harmful? You bet it is!
Well, as it happens, compressed air canisters do not actually just contain canned air. These canisters have a compressed, liquefied gas that propels its vapors through the nozzle. The liquefied gas, most of the times, is of two types; difluoroethane or 152a or tetrafluoroethane or 134a. 152a is found in canisters that are intended for computer or electronic equipment and is also known as Freon. It is also used for keeping the car air conditioner and refrigerators cool. Whereas, the 134a is used when flammability becomes a concern such as for hot surfaces or equipment that might produce sparks. Some compressed air canisters can, however, contain butane – the liquefied gas that is used in cigarette lighters.
As per 3M, the company that produces and sells compressed air canisters for the purpose of dust removal, shaking or even tilting the can may cause the liquid to come out rather than the vapor. If this happens, warns 3M, the user might experience frostbite given that the liquid makes contact with skin or eyes. Medical attention is warranted in such scenarios. Meanwhile, you can wash the affected area with soap and water and make sure to flush eyes using large amounts of water.
What about the aerosol canisters that do recommend shaking before use? The product inside gets separated into layers, and that is why shaking is required to counter any segregation that might have happened. By shaking, you make sure that the product is coming out along with the propellant as well.