The yellowing of newspaper paper over time is due to the oxidation of the chemical compounds present in the paper, mainly lignin. This reaction is accelerated by light, heat, and humidity, which causes the degradation of the paper and its change in color.
Newsprint is generally made from mechanical pulp, primarily derived from softwood fibers such as spruce or pine. Unlike the smooth, high-quality white sheets of premium books, mechanical pulp retains a lot of lignin, a kind of natural "glue" that holds the wood fibers together. This lignin, which is cheap and easy to produce, explains the low cost of newsprint, but it also makes it fragile and sensitive to the elements. During manufacturing, the wood fibers are mechanically ground, mixed with water, and spread into thin layers to form the final sheet you hold between your fingers each morning.
Newspaper yellowing is primarily due to oxidation and hydrolysis. Oxidation is similar to when a cut apple browns when exposed to air: oxygen reacts with chemical compounds present in the paper, particularly lignin. This lignin, naturally found in the wood used to make newspaper, is very sensitive to these reactions. Over time, it degrades and changes structure, forming yellowish to brownish compounds. Hydrolysis, on the other hand, is the chemical reaction where the molecules of the paper react with moisture in the air, further weakening the fibers and promoting this characteristic yellowing. These two combined phenomena alter the molecular structure of the paper, which is what gives that distinctly aged color to newspapers left too long on the coffee table.
Light significantly accelerates the yellowing of newspaper, especially due to UV rays that break down its fibers and oxidize its components, such as lignin. Likewise, when exposed to heat for a long time, paper degrades more quickly, promoting the chemical reaction responsible for oxidation. And when humidity joins the mix, it combines with these factors to worsen the damage: it facilitates the formation of acids that make the paper brittle and even yellower. A not-so-friendly combo, which explains why those old newspapers stored in the attic all end up taking on an ugly yellowish tint.
Newsprint is generally made from mechanical pulp, which leaves a significant amount of acidic compounds in it, notably lignin. These acidic substances react over time with the paper fibers, causing their gradual degradation. Little by little, the paper becomes brittle, fragile, and yellows: this is called acidification. The more acidic compounds accumulate, the faster the degradation of the paper accelerates, significantly reducing its lifespan. In contrast, papers made with fewer acids age much better, maintaining their appearance for longer.
Papers made from mechanical pulp, such as classic newsprint, yellow quickly due to the significant presence of lignin. This reacts easily with air and light, resulting in a yellowish color after a few months or years. In contrast, paper made from chemical pulp (like letter or printer paper) is stripped of a good portion of lignin during its production. As a result, it stays white longer. Specially treated papers, referred to as "acid-free" or "long-term archival", resist aging even better thanks to processes that eliminate the compounds responsible for yellowing. Therefore, they last much longer, even when exposed to light or a bit of humidity.
To preserve your favorite magazine for a longer time, store it in a cool, dark, and dry place to limit yellowing caused by prolonged exposure to light and moisture.
The term 'acid-free paper' refers to paper whose manufacturing process reduces or eliminates the presence of acids, significantly improving its longevity compared to traditional paper.
The cellulose naturally present in paper turns yellow due to the oxidation reaction: this same phenomenon is responsible for the browning of fruit pieces exposed to air!
Did you know that very old newspapers, printed before the 20th century, are often better preserved? At that time, the industrial process often involved higher quality fibers and fewer acids.
No, different types of paper yellow at varying speeds depending on their composition. Papers made from wood (newsprint, recycled paper) generally yellow more quickly than those made from chemical pulp without lignin (archival or high-quality paper), as they contain more reactive compounds such as lignin.
Sure! Here’s the translation: "Yes, often yellowing indicates that the fibers are degrading, making the paper more fragile and brittle. It is the oxidative and acidic chemical processes responsible for this yellowing that lead to structural deterioration of the paper over time."
To better preserve your old newspapers, store them under suitable conditions: away from direct light, in a cool place (ideally 18-20°C), dry, and protected from significant fluctuations in temperature and humidity. Also, consider using acid-free sleeves or boxes for optimal archiving.
It mainly depends on the manufacturing process, particularly the type and proportions of mechanical pulp fibers, as well as the amount of residual chemical compounds such as lignin and acids present in the paper. Environmental factors such as humidity, heat, or exposure to light can also accelerate yellowing.
Unfortunately, it is not possible to completely stop the yellowing of newsprint. However, storing the paper in a cool, dry, dark place and protecting it from moisture will significantly slow down the process by limiting oxidation and acidic reactions.
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