Just as technology has changed over the years, so have nails. They were not always round like we see today. In fact the type of nail used can help you in identifying the time period a piece of an antique piece of furniture or a picture frame was made.
The current type of nails that we use are called wire nails. These have been with us since the 1900′s. Of course there are many different types of nails today but hisorically, there were much fewer.
Up until the late 1700′s nails were made by Nailers. Each one painstakingly done by hand. They were expensive for the time and many people made their own nails using their fireplace. In fact, when a family moved, often they burned their home to the ground so that they could take the nails with them to be used on their next home.
Flat cut nails were first introduced to the United States in the early 1800′s. Originally made of iron they were finally able to mass-produce them. They are often called square nails because the cross section is basically rectangular. By 1900 the wire nail was taking hold although flat cut nails made by iron smith’s were made as late as the end of the 20th century, albeit, in the more populated areas, mass produced nails were used.
Although the type of nail used will not absolutely pinpoint the timeframe, it can give you clues into the history and the story of the piece.