Nugget of Knowledge: Why paper turns yellow

Lignin in paper causes the yellow discoloration

Nugget of Knowledge

YOUNGSTOWN, Ohio (WYTV) – Why does paper turn yellow?

We make paper from wood pulp, and wood pulp contains a protein called lignin.

Lignin is what gives wood its strength, but when exposed to air and light, lignin starts to turn yellow or brown.

Newsprint contains a lot of lignin and so it goes yellow fast.

We chemically treat higher grade paper — the kind we find in books– to remove most of the lignin, and we also bleach book paper, but a little lignin usually remains.

If you want to keep old newspapers, store them in a cool, dry, dark place.

Don’t put them in an attic or your basement. Those places can get humid and have big temperature swings.

If you want to display the newspaper or document in the open, put it behind UV protected glass.

Most importantly, try not handling it. Nothing destroys a valuable piece of paper like touching it all the time.

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