Choosing Paper for Your Printing Project... Part 1
Caliper is the actual thickness measured in mils (1/1000”) or points. Paper that measures 0.010” thick is 10pt, 0.014” thick is 14pt, and so on.
Weight is the “basis weight,” which is how much 500 sheets weigh at a specific sheet size: 25” x 38” for text weights, and 20” x 26” for cover weights. If 500 sheets of 25”x38” paper weighs 80 lbs, that would be 80lb text and 500 sheets of 20”x26” cover weighing 100 lbs. would be 100lb cover. Often “lbs” is replaced with the “#” symbol, so 100 lbs = 100#. Get the idea? Good! Let’s move on.
Bulk is the overall density of the paper. Like how the metric system measures “mass” instead of weight (on the moon you would weigh less, but your mass still takes up the same amount of space.) It’s a formula that considers Caliper and Weight. In simple terms, thicker sheets have more bulk. Also, coated sheets have less bulk then uncoated sheets, which helps explain why 100# coated cover feels much thinner and less stable than 100# uncoated cover.
Next, paper is classified into two categories: Text and Bond. Cardstock has more categories: Bristol, Index, Cover and Board. Bond or Writing is your general multipurpose paper. It ranges from copier-grade 20# bond all the way up to nice fancy resume-type papers like 28# writing. Text is what’s often used for books, newsletters, flyers, etc. Here’s where confusion starts… in terms of thickness 50# text is equal to 20# bond, 60# text equals 24# bond, 70# text equals 28# bond, and so on.
Bristol, also called Vellum Bristol, is a lightweight cardstock. The surface is a little rougher since it isn’t compressed when it gets made. It feels a little thicker, even though it’s not as dense. This makes it less expensive and is often used for mailers and single-use pieces. Index is smoother and feels thinner and is often used for tabs, file folders – and you guessed it – Index Cards!