Dating square cut nails
Hand-hammered nails, dating from the 1700s or earlier, leave a square hole with an irregular impression at the top from a hammered head.
Cut nails leave a more rectangular hole and around or rectangular head.
(1) A dating nail should be driven in the upper side of every treated tie ten inches inside of the rail, and on the line side of the track. While nails are being tested, the temperature shall be at no time less than 60° F. Design The shank of nail shall be one-fourth inch in diameter and 2½ inches long; the head of nail shall be five-eighths inch in diameter and one-sixteenth inch thick, and shall bear two raised figures designating the year, the figures to be three-eighths inch long and raised one-sixteenth inch, and of the following type.
The tie should be laid with the end having the year stamped on it on the line side of the track. Any specimen shall be capable of withstanding the following test: The sample shall be immersed in a standard solution of copper sulphate for one minute and then removed, immediately washed in water thoroughly, and wiped dry; this process shall be repeated.
The nail has a tapered rectangular shaft but straight on two sides, and the shaft is smoother than that of the hand-hammered nail.
The head is usually round or rectangular but sometimes has an off-center notch.
Later, machine did the cutting, but nails were still made one at a time.
Iron ore and carbon heated together and then cooled created wrought iron, from which a nail length piece was cut and hammered on four sides to create a point. The two numerals on their heads are the last two numerals in a year. Chicago: American Railway Engineering Association, . DATING NAILS Material The nails shall be made of iron or steel, galvanized with a coating of zinc (prime western, or equal) Figure 322 evenly and uniformly applied by the hot-dip process so that it will adhere firmly to the surface of the iron or steel. They came into use when railways began to treat ties with preservative, as a way of monitoring which treatments worked best, and gradually went into disuse as wood preservative technology matured and other means of marking dates were introduced.¹ Still, some were driven as late as . Chemical Requirements (a) The sample shall be immersed in a standard solution of copper sulphate for one minute and then immediately washed in water thoroughly and wiped dry. If after the fourth immersion there is a copper-colored deposit on the sample, or the zinc has been removed, the lot from which the sample was taken shall be rejected. 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.