Why Book Paper Turns Yellow?

Book paper turns yellow primarily because oxidation of lignin. Lignin is a natural polymer that can be found in plants (polymer is a large molecules that made by bonding). It breaks down cellulose when exposed to air and light and caused the paper to discolor.

Why some paper are slower to yellowing?

Higher quality paper has more lignin removed, so it will yellows slower than cheaper paper. This is why newspaper yellows faster.

There is a paper which is lignin-free that has pH 7 (neutral). The only downside of this paper is expensive. Wood-free paper is still using wood btw.

How to make paper yellow slower?

We can’t stop it from yellowing.

Avoid UV ray. Humidity is as bad as sunlight. The ideal is 30-50%. Direct exposure to AC can be damaging because the temperature changes.