top of page

Answers to Your Questions

Ask a Question about Our Exhibits

Do you have a question about one of our exhibits that you can't find an answer to? Ask your question here and we will do our best to find an answer. Your name and email address are used for responding to you personally and will not be posted on the website.

Thank you for your question!

Answers

What are the nails with the numbers on the heads in the railroad exhibit?

May 4, 2024. The nails are railroad date nails. Date nails were a quality-control measure that allowed railroads and tie manufacturers to determine the lifespan of wooden cross ties and other wooden structures. Railroad date nails were first introduced in 1897 by the Mississippi River & Bonne Terre Railroad, and were common in the US from 1900 to 1969. A two-digit number indicated the year the cross tie, bridge timber, utility pole, or other wooden structure was manufactured.


Date nails came in round, square, diamond, and pentagon shapes. The numbers were both raised and inset, depending on railroad and/or nail manufacturer. Neither one was better than the other. Raised numbers could deform while being hammered into the wood, but inset numbers could fill with dirt and soot making them hard to read.


Two-digit numbers indicated the year and make up the vast majority on date nails. A "24" on the head of a date nail indicated 1924. Other nails were called code nails. Single-digit nails were often used for numbering switches or other structural elements. Letters often referred to the tie condition or treatment method.

Steel was, by far, the most common material date nails were made from. Copper, iron, aluminum, and brass were also used. The heads were typically 1/2 to 5/8 inches in diameter with a shank 2 to 3 inches in length.


For Santa Fe, a date nail with a round head shape was used in treated ties and timbers. A square or a diamond (considered a square) head shape was used in untreated ties and timbers. A pentagon head shape was used in second-hand ties and timbers. When a tie was reused, the pentagon-headed nail showed the year the tie or timber was reused.


For Santa Fe, code nails had “ST” for Special Treatment or possibly Steam Treatment. “OZ” indicated Oil-Zinc treated. “ZM” indicated Zinc and creosote-petroleum Mixture treated. “X” indicated a Substandard tie.

How does a cream separator work?

May 31, 2024. The answer will go here.

bottom of page