explain xkcd:Editor FAQ
I asked her how long ago she had Secret Death Touches Review graduated from college. She told me it had been 9 years. I did not want to rain on her parade. She was so proud of the fact that she was smart enough to carry pepper spray for self defense. But I could not let her or the rest of the audience go without telling them that defense sprays have an expiration date.As tactfully as I could, I congratulated her for understanding the need to have a self defense weapon available. Then I told the audience that most pepper sprays have a shelf life of 2-4 years.
The active ingredient in pepper spray is capsaicin - a chemical derived from the fruit of plants in the Capsicum genus. The extracted oleoresin capsicum is a wax like resin. This is what causes the burning sensation and the inflammatory effects. An emulsifier such as propylene glycol is used to suspend the OC in water. This compound is then pressurized to make it an aerosol.It is the aerosol component of the pepper spray that can and will break down over time. The "pepper" component will still be hot, hot, hot, but it may not spray out as far as necessary to be effective against an attacker.
Most pepper sprays larger than a key chain sized unit will have an expiration date stamped on the bottom of the container. Key chain models should be replaced after two years, even if there is an expiration date that indicates it would last longer. Pepper spray should be kept at room temperature. The very fact that they are kept on key chains makes them more susceptible to being left in hot vehicles. This exposure to heat can accelerate the break down of the propellant. The last thing you want to happen is to find yourself facing an attacker and pull out your self defense spray only to find that it just dribbles out of the container instead of shooting a stream into their face.
