The magnetism of a safety pin depends entirely on the material from which it is manufactured. Most common, modern safety pins are strongly attracted to a magnet, but they are not permanent magnets themselves. This attraction occurs because the metal contains iron, a substance that responds powerfully to a magnetic field. The specific composition of the pin dictates its magnetic behavior, which can range from a strong pull to no reaction.
Safety Pin Composition
The majority of safety pins are fabricated from steel, an alloy of iron and carbon. Iron is the element responsible for magnetic attraction, meaning a standard steel safety pin will readily stick to a magnet. This material is chosen for its strength and cost-effectiveness.
Some manufacturers use different materials, such as brass or specific grades of stainless steel, to prevent corrosion or for specialized uses. Brass does not contain iron and is therefore not attracted to a magnet. Stainless steel is an alloy that contains iron, but elements like chromium and nickel can alter its internal structure. Certain high-grade stainless steels, such as the 300 series, are non-magnetic despite containing iron.
The Science of Attraction
The property that causes attraction to a magnet is called ferromagnetism, derived from the Latin word for iron, ferrum. Materials like iron, nickel, and cobalt possess this property because of how their electron spins align. Within the steel, there are microscopic regions called magnetic domains, where the magnetic fields of individual atoms are aligned.
In an unmagnetized safety pin, these domains point in random directions, canceling out their magnetic influence. When the pin is brought near an external magnet, the strong field forces these internal domains to rotate and align. This alignment creates a temporary magnetic field within the safety pin, causing the attraction. The pin is drawn toward the external magnet because the newly aligned domains generate a field that interacts with the magnet’s field.
Testing and Induced Magnetism
The easiest way to determine a safety pin’s magnetic nature is to place it near a common magnet. If the pin is made of standard steel, it will be pulled toward the magnet with noticeable force. This test reveals that the pin is not permanently magnetic but is susceptible to an external magnetic field.
A safety pin made from a ferromagnetic material can exhibit a temporary magnetic effect through induced magnetism. By repeatedly stroking a permanent magnet across the pin in the same direction, a person can temporarily align some of the pin’s internal magnetic domains. This process briefly turns the safety pin into a weak magnet, allowing it to pick up small metal objects like paperclips for a short time.