What method is typically used for valuable saturated books and documents to prevent damage?

Freeze-drying is an effective method for preserving valuable saturated books and documents because it minimizes damage that can occur from moisture. When a document or book is saturated, it is at risk of mold growth, ink bleeding, and cellulose degradation. Freeze-drying works by initially freezing the item, which solidifies the water content. Then, through a process called sublimation, the ice is removed under vacuum conditions without passing through the liquid phase. This method ensures that the delicate materials are not subjected to the physical stresses and potential tearing that can come from air drying or heat drying processes. Moreover, freeze-drying helps to stabilize the structure of the paper and maintain the integrity of the ink and other materials used in the documents, making it the preferred choice for valuable texts.