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What does "basis weight" really mean? What is the difference between poster board and railroad board? With so many paper terms, it's hard to keep everything straight. Even for us Pacon folks.

Luckily we work with Steve Spangenberg, our appointed in-house paper expert. He has been with Pacon for 15 years, and frequently gives "Paper 101" presentations to both customers and Pacon employees. We're very lucky to have him on our team, because the paper business can be very confusing.

"The differences between all the board types is what I get the most questions on," Steve said.

Pacon offers railroad board, poster board, tagboard, foam board, presentation board and display board. People are most confused about what the differences are between railroad board and poster board. A lot of people think that the terms are interchangeable, but that's not the case.

"What makes poster board and railroad board different is mostly the way they are made," Steve explains. "Colored railroad board uses dyed fibers, and is made in layers or plies. Poster board uses a base stock, and then colors are coated on the top and bottom of the base stock."

Why is it called railroad board? There are a few theories on how board was used. 

  1. Train station attendants would hand write signs to slide into wooden frames that would tell which platform a train was on. 
  2. Colored railroad board was used to show railroad switchmen where to put various railroad cars. Many spoke different languages so color coding was necessary.
  3. Immigrants at Ellis Island were given colored cards to direct them to the coordinating train, which would take them to their destination.

When choosing which board is best for your project, consider such things as size and fade-resistance. The below chart helps to quickly show the differences between the two types of boards. 

  Railroad Board Poster Board
Manufacturing Process Fibers are dyed into the sheet and it is made in layers or plies (Uncoated) Colors are coated on top and bottom of a base stock
Fade Resistant No Yes
Available Sizes 22" x 28" 11” x 14”, 14” x 22”, 22” x 28”
Caliper (Thickness) 4-Ply (14 pt.) & 6-Ply (20 pt.) 12 pt. & 18 pt.
Railroad board is measured in plies (or layers). Depending on how many layers are created in the manufacturing process determines the thickness or ply of the finished board. As each ply is added together, the increased thickness (caliper) is described by the total number of plies.
Because poster board is made different than railroad board, caliper is measured by point (pt.). Each point is equivalent to .001 inch.
"Basis weight is another topic I get asked about," Steve said. "The tricky thing about basis weight is that each type of paper uses a different scale."
Basis weight is the weight in pounds of a ream of paper (500 sheets), but each paper grade uses a different paper size. The below chart provides a comparison between the paper types, sheet size and the weight in pounds. For a universal comparison, grams per square meter (gsm) is a good comparative measure because it does not vary with sheet size.
For those who don't have a resident "Steve" to provide definitions and explanations on demand, we include a few different resources on our website, including a paper glossary, an easy-to-follow board identification chart and more.

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