Answered by Amy Kearns, Manager of Worldwide Product Planning and Marketing Strategy, Supplies Business Group, Xerox Corporation

Question:
What is the difference between a text stock and a cover stock of the same weight (i.e.: 60 lb. text stock and a 60 lb. cover stock)? I know that the cover stock is stiffer, but what creates that difference? Also, are there any quantifiable characteristics that determine whether a stock is bond, book, text or cover, or is it just at the paper supplier's discretion?

Answer:
To answer your question completely involves explaining several facets of the art and science of paper making. The key facets, for this discussion, include size, weight and grade. These aren’t the only factors but if you are interested in learning more, a number of books describe the history of paper making and current processes.

First, paper is categorized by the size of the sheets as it has been traditionally manufactured, addressing the science of paper making.

Size and Weight:

• Business and related papers
  • Basic Size 17” x 22” (types of paper)
    • Bond
    • Carbonless paper
    • Copy paper
    • Envelope
    • Form bond
    • Safety (for checks, secure documents)
    • Laser bond
    • Ledger
    • Tablet
    • Translucent bond
    • Xerographic bond

• Advertising and related papers – coated and uncoated
  • Basic Size 25” x 38” (types of paper)
    • Book
    • Gravure
    • Label
    • Offset
    • Opaque
    • Text
    • Vellum

  • 20” x 26” - types of paper: Cover

  • 25 ½” x 30 ½” - types of paper: Index Bristol

  • 22 ½” x 28 ½” - types of paper: Printing Bristol

  • 24” x 36” - types of paper: Tag stock

The basic size is used to establish the basis weight of the respective grades. The basis weight represents the weight of 500 sheets in the dimension shown.

That means basis weights for any two kinds of paper can be difficult to compare if their standard sizes differ. This is often where confusion arises when you are comparing a 60 pound (usually abbreviated to lb. or #) text (basic size 25” x 38”) and a 60# cover (basic size 20” x 26”).

Therefore, part of the difference between 60 pound cover and text weight papers is how they are sheeted and measured. This is also one of the most quantifiable characteristics separating bond, book, cover and text classifications from one another.

Based on production process – it is more correct to see certain weights referenced by different segments of the market. Text and Cover weights are commonly used in the commercial print and design communities, while Bond weights are more commonly used in office environments. This is based on the historic origins of where the grades have been most commonly used. The metric system of grammages, which is starting to be seen in some paper marketing materials, helps avoid some of the confusion generated by the historic and confusing basis weight structure.

Grade
Grade relates to a type of paper distinguished from other papers by its characteristics such as its raw material content (fibers obtained from softwoods or hardwoods and so on), physical characteristics, types of printing process the paper will be used in, end use, etc. Grade represents the broad classification for a common set of paper characteristics and determines – how it feels, looks and performs. This brings in some of the art of paper making as it is much more subjective rather than objective.

All types of paper, pulp, paperboard and converted paper products are classified and subclassified using the U.S. Department of Commerce, Bureau of Census’ Standard Industrial Classification System (SIC). The extensive classification of grades used by the American Forest & Paper Association (AF&PA, www.afandpa.org) closely parallel the S.I.C. system and provides a more detailed breakdown for some grades.

The same grade of paper may come in different weights too. Common weights for bond, for example, are 20# and 24#. This refers to paper manufactured using the same recipe, raw materials and basic size though the 24# sheets are slightly heavier -- making a stack of 500 sheets four pounds heavier than a corresponding stack of the 20# sheets.

Going back to the 60# text and cover examples, a paper company may make a group of matching papers where the grade characteristics are the same but the sheeted size and, weight are different. In this way, a manufacturer may offer the same paper in several text and cover weights so you can create a uniform, pleasing appearance in a single printed piece.

Commonly used Bond/Text Conversions are:

• 20# = 50#
• 24# = 60#
• 28# = 70#
• 32# = 80#

Part of the information used in this answer was sourced from Walden’s Paper Handbook, Third Edition, ©1995 Walden-Mott Corporation.