Why do newspapers and old books turn yellow with age, and is there anything we can do to prevent or preserve important clippings?

-Karthik Gurumurthy

Newsprint paper contains a lot of acid and lignin. The acid causes the paper to disintegrate, while lignin is what turns paper yellow or brown over time. Lignin is essentially a polymer that acts as a binder or glue holding the wood fibers (cellulose) together. When paper mills want to make fine white paper, they put the wood through a chemical solvent process that dissolves the lignin. Pure cellulose is white, and paper made from it stays white and resists yellowing.

Newspaper publishers don’t really care if their newsprint turns yellow with time. Their priority is cheap paper, which they achieve by skipping the chemical treatment. Newsprint is designed as a temporary medium, meant to be used for just a few days and then discarded.

The yellowing occurs because lignin molecules become less stable when exposed to oxygen. The lignin absorbs more light, giving off a darker color. If newsprint were completely protected from light and air, it would stay white – though that would make it rather difficult to read!

In some cases, lignin in paper is actually desirable. Brown grocery bags and cardboard are good examples. The lignin makes them strong and sturdy, and they don’t typically need to be printed on extensively anyway.

I’ve noticed people often cut newspaper clippings for scrapbooks – perhaps an obituary, award announcement, or event they attended. After several years, they discover the newspaper article has badly deteriorated. The best solution is to make a copy of important newspaper articles using acid-free, lignin-free white paper.