Until about 1800, nails were hand-forged – tapered square shafts and hand-hammered heads. During the 1800s, cut nails have tapered rectangular shafts and rectangular heads. In the 1900s, the round wire nail with straight sides and a round head are the standard.

When did square nails stop being used?

Square-head nails were made from the late 1700s until about 1830. Most were machine-cut and finished off by a blacksmith who squared the heads. From 1830 to 1890, cabinetmakers used headless, machine-cut nails that are a tapered, rectangular shape.

When did they switch from square nails to round?

These machine/handmade nails were used up to the end of the 19th century. By the 1890s, the entire nail was completely machine formed producing the rounded shank or wire nail that continues in use today.