Within thirty years, wood pulp paper was all the rage on both sides of the pond. While wood pulp paper was cheaper and just as durable as cotton or other linen papers, there were drawbacks. Most significantly, wood pulp paper is much more prone to being effected by oxygen and sunlight.
Wood is primarily made up of two polymer substances — cellulose and lignin. Cellulose is the most abundant organic material in nature. It is also technically colorless and reflects light extremely well rather than absorbs it which makes it opaque ; therefore humans see cellulose as white. However, cellulose is also somewhat susceptible to oxidation, although not nearly as much as lignin. Oxidation causes a loss of electron s and weakens the material.
Lignin is the other prominent substance found in paper, newspaper in particular. Lignin is a compound found in wood that actually makes the wood stronger and harder. In fact, according to Dr. Hou-Min Chang of N. Lignin is also highly susceptible to oxidation.
Exposure to oxygen especially when combined with sunlight alters the molecular structure of lignin, causing a change in how the compound absorbs and reflects light, resulting in the substance containing oxidized lignin turning a yellow-brown color in the human visual spectrum.
Since the paper used in newspapers tends to be made with a less intensive and more cost-efficient process since a lot of the wood pulp paper is needed , there tends to be significantly more lignin in newspapers than in, say, paper made for books, where a bleaching process is used to remove much of the lignin.
The net result is that, as newspapers get older and are exposed to more oxygen, they turn a yellowish-brown color relatively quickly. However, the chemicals used in the bleaching process to make white paper can result in the cellulose being more susceptible to oxidation than it would otherwise be, contributing slightly to the discolorization of the pages in the long run.
Today, to combat this, many important documents are now written on acid-free paper with a limited amount of lignin, to prevent it from deteriorating as quickly. It is important to store the documents or newspaper in a cool, dry, dark place, just like how museums store historic documents in a temperature-controlled room with low-lighting.
Additionally, do not store them in an attic or basement; those places can get humid and can have significant temperature swings. This special paper absorbs damaging acid from the pages, keeping them in top condition.
Some general tips and common knowledge go a long way: handle your books with clean hands; don't place them on dirty or wet surfaces; use plastic covers for added protection; dust and clean your library regularly; and make sure your books won't get bent or wrinkled if you're taking them with you in your bag.
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Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Physical Science. Chemical Processes and Tests. Why do newspapers turn yellow over time? Lignin makes wood stiff and trees stand upright.
It eventually turns paper yellow because of oxidation. Why doesn't paper money disintegrate when it gets washed in the washing machine?
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