雙語：爲什麼報紙放久了會變黃

This Is Why NewsPapers Turn Yellow Over Time

爲什麼報紙放久了會變黃

If you’ve ever stumbled across old newspapers, you might have noticed an interesting trend: Most of them are yellow—and no, they weren’t always that way. In short, this color-changing phenomenon is due to the process of oxidation. (In other words, the same process that turns a half-eaten apple brown.)

如果你偶然翻看舊報紙，你可能會注意到一個有趣的情形：大多數報紙都是黃色的，當然，它們並非一直如此。簡而言之，這種變色現象是緣於氧化過程。（換句話說，這和只吃了一半的蘋果會變成褐色是同樣的過程。）

To break down this scientific process, let’s start with the basics. Paper is made from wood, and wood contains two substances called cellulose and lignin. When the chromophores (molecules responsible for color) found in lignin are exposed to air and sunlight, the lignin’s molecules become less stable and absorb a greater amount of light. In turn, the newspaper’s hue gradually darkens from white to yellow.

我們從其基礎開始，來分解這個科學過程。紙是由木材製成的，木材含有兩種物質，分別叫做纖維素和木質素。當木質素中發現的髮色團（用於顯色的分子）暴露在空氣和陽光下時，木質素的分子就會變得不那麼穩定，並吸收更多的光。緊接着，報紙的色調逐漸從白色變爲黃色。

The reason newspapers are more prone to this color change, in comparison with other types of papers, is because the wood’s lignin isn’t typically filtered out. This both saves on the costs of mass daily printing and leaves the papers more prone to oxidation. (A chemical process called conservation bleaching can be used to produce yellow-resistant papers to avoid discoloration over time.)

與其他類型的紙張相比，報紙更容易出現這種顏色變化的原因是因爲木材的木質素通常沒有被過濾掉。這既節省了大量日常印刷的成本，又使紙張更容易氧化。（一種名爲保護性漂白的化學過程可用於生產防氧化紙，以避免紙張隨着時間的推移而變色。）

Fortunately, the lifespan of newspapers can be lengthened if they’re stored properly. The best way to preserve newspapers is to keep them out of sunlight and store them in acid-free and buffered boxes. Doing this allows the acids released by the papers to be neutralized by the alkaline buffers, helping the papers retain their white color.

當然有幸的是，如果報紙存放得當，它的使用壽命可以延長。保存報紙的最佳方法是讓它們遠離陽光，並將它們存放在無酸並有緩衝的盒子裏。這樣能使紙張釋放的酸被鹼性緩衝液中和，使紙張保持白色。

（翻譯：MS小冰晶）