Most of us are familiar with the old square nails used centuries ago. We’ve seen them on display at museum homes, or historical society exhibits, or perhaps being hammered out by blacksmiths in places like Plimoth Plantation or Colonial Williamsburg.

What many of us are unaware of, however, is that those old nails were actually superior in design to modern wire nails. They have several times the holding power, and are less likely to cause wood to split. And perhaps even less well known is the fact that square nails are still manufactured today. They are even available in bulk quantities.

Hand forged 17th century iron nails and spike in the roof system of the Old Hawkins house, Derby, Connecticut

Two 2.5" (8d) square-cut iron nails I extracted from a door jamb, causing an oyster shell to break free from surrounding plaster

Top: Hand forged 17th century iron nails and spike in the roof system of the Old Hawkins house, Derby, Connecticut. Bottom: Two 2.5″ (8d) square-cut iron nails I extracted from a door jamb, causing an oyster shell to break free from surrounding plaster (oyster shells were used as thickeners in early plaster walls).

Old Square Nails are Old

Hand-forged iron nails predate the ancient Romans. The basic form of the modern wrought square nail was developed in sixteenth century Europe. When the first settlers began arriving in the New World in the early seventeenth century, they brought large quantities of wrought nails with them. Nail making was never done on a very large scale in the American colonies. Nails primarily imported from England, right up until the Revolution.

Around the 1790’s, American inventors had prototyped the first nail making machines. These produced square-cut nails by cutting them from iron rods. By the early 1820’s, nail-making machines had become so efficient that America soon became the world’s leading manufacturer and exporter of nails.

Modern square-cut steel nails by Tremont Nail Company

Modern square-cut steel nails by Tremont Nail Company. From left to right: 4″ (20d) cut-spike (HDG), 3.5″ (16d) cut-spike (HDG), 3.5″ common, 2.5″ (8d) fireboard clinch (HDG), 2″ (6d) rosehead common, 2″ wrought nail, 1.5″ (4d) wrought nail, 1″ (2d) wrought nail, 1″ brad, and 1″ headless brad (for fine finishing) (HDG=hot dip galvanized)

Square Cut Nails are Superior

Square-cut nails are fundamentally superior to modern wire nails because of their superior holding power. If you’ve ever attempted to extract a square-cut nail from a board, you know what I’m talking about. They hold so tenaciously that you’ll often break the board or the nail itself before removing it. The reason for this is the shape of the shank. It usually tapers on two opposite sides from head to tip, resulting in a chisel-shaped point. The four edges of the shank also tend to be very sharp.

When driven with the correct orientation (non-tapered sides parallel to the grain), the tip and edges shear the wood fibers rather than push them apart as wire nails do. Then, the shank finally wedges itself tightly into the wood. Because of their shearing ability, square-cut nails tend not to split wood. They can be used closer to the edge or end of a board than a wire nail.

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A 3.5" (16 penny, or 16d) square-cut bright common nail and it's equivalent wire nail cousin

A 3.5″ (16 penny, or 16d) square-cut bright common nail and it’s equivalent wire nail cousin. This 16d square-cut common nail costs about 17 cents. The wire nail goes for about 7 cents, based on the Tremont catalog and my local Home Depot, respectively. The square nail is about 2.4 times as expensive as the wire nail. But they have about 4 times the holding power. Interestingly enough, in terms of the old penny weight costing system, either nail would’ve cost about 0.2 cents a piece back in the old days. Albeit in Colonial pennies, not modern U.S. pennies.

Modern Nails Squeeze In

Modern wire nails were invented in the late nineteenth century. Improved industrial processes simplified the formation of round wire rods from soft steel. Nailing machines then retooled to cut nails from less expensive round wire. The cheaper, mass produced cut-wire nail met with instant market success during America’s westward expansion, and it forced the manufacturing of square-cut iron nails into eclipse.

Today, wrought square nails are still used in historical restoration projects. Obtained directly from blacksmiths or ordered through vintage hardware suppliers. Also, many of the larger living history museums, such as Colonial Willamsburg, maintain their own blacksmith shops that supply their sites with historically accurate, forged nails.

Simple wood floor mock-up I created using 2x4s and oak scants of different widths.

Simple wood floor mock-up I created using 2x4s and oak scants of different widths. I’ll often build simple prototypes like this to experiment with different combinations of wood species, stain, and nail types. In this particular one, I am comparing common rosehead nails (first three boards, left to right) and wrought nails (fourth and fifth boards on the right). (I have yet to apply any stain to these boards). I’m not sure I like the look of the roseheads when face nailed. I think they would look better counter sunk. We’ll try that next…

Square Cut Nails are Still Available

Square-cut nails, on the other hand, are still available from the Tremont Nail Company, of Mansfield, Massachusetts. Tremont, which today is a division of Acorn Manufacturing. (You might remember them from our post on Wood Window Shutters.) The company was founded in 1819 in response to the Federal Period demand for low-cost nail production. It is the only remaining American nail company producing square-cut nails. Today, Tremont makes square-cut nails out of steel, rather than iron. Their common nails made from hardened, high-carbon steel.

Editor’s Note: Bob Vila toured Tremont Nail back in 2011.

They even offer hot-dipped galvanized versions for outdoor applications. But the truly amazing thing about Tremont is that they still use their own vintage nail-cutting machines. These date back to the 1850s. Over the years, they’ve managed to keep these machines running by fabricating replacement parts when necessary. So these reproduction nails are hardly reproductions at all. Harder and stronger than iron, they are more of a generational advancement in square-cut nail technology, rather than simple copies of historic artifacts.

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The wrought nails look much better for face nailing in oak,

The wrought nails look much better for face nailing in oak, in my opinion. We’ll have to see how they look with different stains and a polyurethane overcoat.

So, the next time you’re touring an historic home or colonial settlement museum, keep in mind the old adage that a wooden structure is only as strong as its fasteners. And you may more fully understand just why some of these old buildings are still standing. The construction techniques of our forebears were not necessarily inferior to our own. Some were actually better, only succumbing in the end to that ages-old practice of trading utility off in favor of reducing costs.


Note from the hosts: Thanks for visiting. The perfect blend here – we’re Old House fanatics that love to geek on both Building History and Building Science. We welcome you to stick and click. Cheers. ~jb