The Complete Handbook of Safety Pins

Chapter 1: Understanding Safety Pins

The safety pin is a coiled spring with a pointed wire that returns to a protective guard. That is the entire mechanical description, and it has not changed in any fundamental way since Walter Hunt patented the device in 1849. Hunt's original design solved a simple problem: he owed a friend fifteen dollars and needed to invent something to sell the patent rights for. He twisted a piece of brass wire into a coil, added a clasp at one end and a point at the other, and sold the rights for four hundred dollars. The buyer, W.R. Grace and Company, made a fortune from it. The mechanical logic of that first pin is identical to the logic of the pins you buy today, a century and three-quarters later. A coil of wire stores elastic energy. When you open the pin, you deform the coil. When you release it, the coil wants to return to its original shape, and that returning force pushes the point into the guard and holds it there with a specific, measurable clamping pressure.

Understanding that the pin is a spring and not just a bent wire changes how you evaluate one. The coil is not decorative. It is the engine. Its diameter, the number of turns, the wire gauge, and the alloy from which it is drawn all determine how much force the pin exerts and how many open-close cycles it can survive before the metal fatigues. A cheap pin with