Bear spray is NOT a repellant
Do not spray clothing, tents, backpacks or any other objects in an effort to deter bears from you or your campsite. In fact, if the can is sprayed the oily, resin-like substance that is released may actually attract bears in the same way food might.
Bear spray is only effective if you can reach it
Bears look big and slow, but they can run about 50 ft/sec (more than twice as fast as we can run). This means that you may only have a few seconds to grab the can and spray it. It is recommended that you wear the spray on your right or left hip depending which hand you rely on.
Only use the spray if a bear approaches within 30 feet
Bear spray is designed to create an atomized fog, which produces a pepper cloud that slowly dissipates. The fog will not affect the bear until it gets within 30 feet of you.
Using bear spray is not as intuitive as you might think
You need to consider wind direction and then try position yourself upwind if possible, to avoid cross-exposure. You also need to aim low at the head and face of the bear so it runs into the spray—it is possible for a charging animal to run under the fog if it is sprayed too high. It is also a good idea to practice removing the safety clip on the can with the same hand you’re holding it with. You may only have one hand available to grab and use the spray, so you want to feel confident that you will be able to do so in a matter of seconds. The safest way to practice using bear spray is to buy an inert can of bear spray (canister contains propellent only) and really get a feel for how it works.
Bear spray must be stored properly to avoid accidental exposure
The inside of a car with the windows closed can reach temperatures over 181 °F. Bear spray can explode at a temperature of about 120 degrees. Get in the habit of always transporting the bear spray in the bed of your truck or in a trunk, not in the cab of the vehicle.
Bear spray does expire
Check the date on your cans and properly dispose of any expired cans of bear spray. Most cans expire after 2 years.
When purchasing bear spray it is important to note that self defense sprays like mace are not the same as bear spray. The EPA (Environmental Protection Agency) regulates bear sprays, so look for the EPA registration and establishment numbers found on the front of the label.