Nail (fastener)

A nail is a small but essential fastener used in woodworking and construction. These objects can hold materials together, serve as pegs for hanging items, or act as decorations.

Most nails feature a sharp point on one end and a flattened head on the other. However, some versions are headless. Nails work through two main physical principles. They use friction in the axial direction to stay in place. They also provide shear strength to resist lateral movement.

In some cases, a worker might bend the point over, a process called clinching, to prevent the nail from pulling out.

Historically, the production of nails has moved through three distinct periods. The first was the hand-wrought or forged era, which lasted from pre-history until the 19th century. The second was the era of the cut nail, occurring roughly from 1800 to 1914. The third is the wire nail era, which began around 1860 and continues today.

During the hand-wrought period, a smith worked an iron pin into a conical shape. They would insert the broad end into a nail-header, which is an iron plate with a small hole. By hammering the pin against the plate, the metal flattened to form a head. This manual process was slow and required great skill.

The transition to mechanization began with the introduction of the slitting mill in 1590. This machine helped produce nail rods by cutting iron bars into even cross-sections. Between 1790 and 1820, inventors began automating the nail-making process itself. This led to the rise of the cut nail, also known as the square nail. These nails were produced by cutting iron bars into rods, resulting in a rectangular cross-section. Jacob Perkins patented this process in the United States in 1795. Joseph Dyer also established similar machinery in Birmingham, England.

Cut nails changed how buildings were constructed. Their availability helped increase balloon framing starting in the 1830s. This shift led to the decline of traditional timber framing that relied on wooden joints. However, cut nails eventually lost popularity to the wire nail. Wire nails are made from coils of wire drawn through dies to reach a specific diameter. A machine then cuts these into short rods. A blade cuts the tip, and high pressure forms the head.

By 1913, wire nails accounted for 90 percent of all manufactured nails.

Nails have often been treated as valuable commodities. In the American colonies, they were so expensive that people sometimes burned abandoned houses. They did this to recover used nails from the ashes. In Virginia, laws were even created to prevent people from burning houses just to collect metal. Families sometimes worked at home at night to make nails for barter. Even Thomas Jefferson noted that he was a nail maker. In medieval England, the term "penny" was used to describe the price of one hundred nails.

There is a massive variety of nail types designed for specific tasks. Common types include brads, which are small and thin, and tacks, which are short and sharp. Oval brads are specialized to prevent wood from splitting by cutting fibers rather than wedging them apart. Other examples include roofing nails, aluminum nails for architectural metals, and concrete nails. Some nails are even made of wood or copper, such as those used by the Salish people.

You can also find heavy-duty versions like railroad spikes or horseshoe nails.

Today, most nails are made of steel. Ordinary wood nails use mild steel, which has about 0.1% carbon. Nails for masonry are tempered and contain a higher carbon content to handle tougher materials. Modern rotary principle nail machines allow for a continuous process. These machines handle wire feeding, cutting, and head forming in one rotating movement. This technology has turned the nail from a precious, hand-crafted item into a cheap, mass-produced commodity used globally.