The bobby pin is a ubiquitous hair accessory that has stood the test of time. The bobby pin was invented in 1922 to manage the en-vogue bob hairstyles. It is also from that hairstyle that bobby pins get their name. Today, bobby pins play as central a role in the maintenance of women's hairstyles as they always have. However, with continual use, bobby pins begin to stretch and no longer hold hair in place. There is no need to discard them as they can easily be made tighter.
Clasp the bobby pin tightly between the thumb and forefinger of your left hand. Hold it up vertically at the open end, the same way you would slide it into your hair.
Take the pliers in your right hand and place the jaws over the bend at the other end of the pin.
Close the pliers slowly so that it gently presses on the bobby pin bend. This will force the two open ends together and tighten the clip. Be careful not to press too hard or you won't be able to open the clip to slide it into your hair.