Acid-free tissues are paper tissues that are manufactured without the use of acidic chemicals, which can cause deterioration and discoloration over time. These tissues are commonly used for preserving delicate items such as photographs, documents, artwork, and textiles. The acid-free quality helps to protect these items from yellowing, fading, and becoming brittle, ensuring their longevity. Acid-free tissues are also used in archival and conservation settings to protect valuable or historical artifacts from damage caused by acid exposure. They provide a safe and stable environment for storing and handling sensitive materials.