If you look at old newspaper clippings, aging paper documents and books that are past their prime, you’ll notice that they likely have a yellow tinge. But why do old paper products turn this golden hue?
It’s not that books would rather be blond, but rather that paper is made from components that yellow over time — at least when they’re exposed to oxygen, Susan Richardson, a chemistry professor at the University of South Carolina, told Live Science.
Most paper is made from wood, which largely consists of cellulose and a natural wood component called lignin that gives land plant cell walls their rigidity and makes wood stiff and strong.
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