Tuesday, April 6, 2010
The Yellowing of National Geographic: Will Today's Copies Age Faster Than That Stack in Your Gramma's Attic?
The National Geographic Society recently revealed that the interior pages of its iconic magazine are printed (in the U.S., at least) on coated groundwood (CGW) paper, which means it contains a natural substance called lignin that is associated with yellowing and degradation of paper. For decades, the magazine was printed on coated freesheet paper, which ages much more slowly because it contains only lignin-free pulp.
Rumors of the magazine’s switch to less costly CGW, which had circulated for a couple of years, were confirmed in a recent Gravure Magazine article (available only to members of the Gravure Association of America) about the society working with Verso Paper to document the carbon footprint of National Geographic's U.S. edition.
“We estimated the forest-to-gate carbon footprint for 50-pound National Geographic Gloss paper with and without recycled content," said Craig Liska, Verso vice president for sustainability, in the article. “The assessment of this coated groundwood product manufactured at our Androscoggin (Maine) mill began with the acquisition of raw materials and ended with the product ready to ship.”
The term “coated groundwood” usually refers to paper consisting of at least 10% mechanical pulp (also called groundwood pulp), which still contains lignin. In wood, lignin acts as a sort of glue that binds wood fibers together. In paper, it leads to yellowing when exposed to oxygen and light.
The article indicates that the paper uses a combination of kraft pulp (from which the lignin has been removed), mechanical pulp, and a small amount of recycled pulp (which may or may not contain lignin). Other ingredients include calcium and carbonate, suggesting that the paper is “acid free” and therefore not as prone to yellowing and degradation as groundwood papers using an acid process.
When it comes to aging, not all groundwood papers are equal. A 30-year-old paperback might crumble in your hands because the paper contains only mechanical pulp. But the paper in a 1980 copy of Sports Illustrated, which (like current copies of National Geographic) contains both kraft and mechanical pulp as well as coating, probably just looks a bit dingy and tattered.
National Geographic’s paper is still extremely bright and white by U.S. magazine standards. Because lignin tends to darken paper, achieving such quality with coated groundwood paper was not possible until recent advances in paper-making technology.
And what about that carbon footprint? It’s just over 29 ounces for a typical copy weighing 12.3 ounces, the article reports; using more recycled pulp had minimal impact on reducing that number. About 70% of the total is from paper manufacturing (mostly from electricity generation and the burning of fossil fuels at the mill), 26% from printing and distribution, and 4% from such other activities as packaging and landfilling. The society plans to conduct similar studies of its other products, then use the data to set goals for reducing greenhouse-gas emissions.
Trying to reduce greenhouse gases could leave the society with a difficult environmental choice. The manufacture of kraft pulp has a low, sometimes no, carbon footprint because black liquor extracted from the wood is burned to generate electricity. But most environmentalists say that mechanical pulp is more environmentally friendly because it uses fewer trees per pound of pulp.
For more information about how some other magazine publishers are reducing their carbon footprint, please see Three, or Maybe Four, Green Magazine Pioneers.