Have you ever wondered why a brand new white sheet takes on a characteristic caramel or deep ocher hue after a couple of decades? This is not just “dust of centuries,” but a complex chemical process that turns a home library into a living monument to organic chemistry.
The main culprit of aging
The main reason for the color change lies in the composition of the wood from which most modern paper products are made. The key component here is lignin – a complex polymer compound that in a living tree is responsible for the rigidity of the trunk and allows plants to grow tall and strong.
When wood is processed into paper pulp, lignin is often retained within the fibers. Under the influence oxygen And sunlight there is a process going on oxidation. Lignin molecules change their structure and begin to absorb more light waves, which our eyes perceive as yellowing or even browning of the material.
Environmental influence
The speed at which pages lose their whiteness directly depends on storage conditions. There are several external factors that accelerate the destruction of cellulose:
-
Ultraviolet radiation. Direct sunlight acts as a catalyst, triggering irreversible photochemical reactions.
-
High humidity. Water promotes the development of microscopic fungi and accelerates acid hydrolysis.
-
Air pollution. Ozone and sulfur dioxide in the urban environment actively attack the leaf structure.
-
Acidity. In cheap types of paper, acids form over time, which literally “burn” the sheet from the inside, making it brittle and brittle.
The difference between a newspaper and an expensive book
You’ve probably noticed that the usual newsprint turns yellow literally in a matter of days in the sun, while high-quality collector’s editions remain white for decades. The secret lies in the degree of purification. When producing budget paper, lignin is not completely removed to save resources. At the same time, for archival documents it is used acid free paperwhich has undergone thorough chemical cleaning, where the lignin content is minimized.
Modern technologies make it possible to create paper with the addition of an alkaline buffer, for example, calcium carbonate. This allows you to neutralize harmful acids and significantly extend the life of the printed word.
Proper storage of books in a dark, dry and cool place helps slow down the natural breakdown of organic fibers.
About the Author
