All About Those Grades & Weights of Papers

And why they do not make sense

Printing is More than Reproducing Words and Images on Paper

IT IS THE PHYSICAL EXPERIENCE ITSELF.
It is not just ink on paper, it is about holding the paper, feeling the paper, the texture, the weight, the interplay of ink on the stock — all can tell an emotional story. As such, paper — the vehicle of the message — represents a substantial cost item in a printed job. Understanding paper and picking the right sheet for your job can make or break your project. So, when helping our clients pick out papers, it is often very confusing because the specification of the paper may be the same, but the physical weights are very different. So what’s up with that?

Papers are defined by grade and basis weight. Understanding these two concepts is the key to specifying the right paper. We often get asked how can a 65# cover stock be heavier than 100# text, well, we hope this will help explain that mind-boggling question.

Basis Weight

Getting more specific, people identify papers in terms of their basis weights. Since coated papers are more compressed (calendered), you can’t necessarily keep the same weight when you switch grades. For instance; you may go from a 60# uncoated to a 70# coated sheet to keep the same thickness. That’s why papers are usually referred to by weight and grade (70# coated).

What is basis weight, exactly? It is the weight of 500 sheets of paper cut to a basis size. So, 500 sheets of 25" x 38", 60# offset weighs 60 lbs. The basis size for bond is 17" x 22"; for text, offset, and coated 25" x 38"; and for cover 20" x 26". That’s why two similar sheets of different grades may have very different basis weights, for instance, 24# bond and 50# offset.

Grades of Paper

There are seven basic grades (or types) of commercial printing papers.

• BOND OR WRITING = Usually used for letterheads, business forms, and copiers.
• BOOK = The most commonly used coated and uncoated papers for printing.
• TEXT = High-quality sheets in a variety of surfaces and colors.
• COVER = Used when greater bulk is required such as book covers, postcards, business cards, or inserts. Available in a wide variety of surfaces and colors.
• TAG, BRISTOL, AND INDEX = Smooth surface papers mostly uncoated, except for bristols. Uses include displays, file folders, and tickets.

Within each grade there are other distinctions based on brightness, opacity, and fiber content. For instance, there are matte, premium, and ultra gloss finishes to coated paper. In uncoated book, there is #1 Offset, #3 Offset, Opaque, and Lightweights. Text papers are distinguished by finishes like smooth/vellum, felt/embossed, laid, and linen.

Recycled Papers

Our national waste disposal challenge has led to the increasing use of recycled papers. Paper companies have answered increasing demand with offerings in all paper grades. While recycled sheets still command a premium over virgin stock, they are more widely available than in previous years.

At this time there are still differences in definitions associated with recycled papers, and concerned buyers need to consult the EPA (Environmental Protection Agency) guidelines, State of California and Federal definitions, and paper companies’ literature to make informed judgments.

Digital Papers

High-speed laser printing, in black and white or full color, lays toner on a substrate. Whether the output equipment is a digital copier, or sheetfed or web digital press, the process requires papers that will stand up to the heat employed in the fusing process in these machines. In the case of inkjet output, compatible papers are also required.

Today, paper mills are developing full lines that work for these processes, as well as offset lithography, so that designers can coordinate campaigns that encompass everything from large-format to short-run personalized print to long offset runs. Be sure that the paper you specify is right for the process that will produce your job.

The same caveats apply to inks

Inks containing certain waxes and some other ingredients will soften as a result of the heat generated in a laser printer or copying machine, which can transfer to the rollers of your machine and make a faint copy of the image down your sheet. Again, let the printer know how your printed piece will be used.

We hope this was useful for you! This information was provided through our membership of Pacific Printers Association.