säurefrei

Säurefrei refers to materials that are free from acids or designed to resist acid-induced degradation. In practice, the term is widely used in archival and preservation contexts for paper, cardboard, envelopes, protective sleeves, and other storage materials that aim to slow down deterioration over time. Säurefreie products are intended to prevent acid migration to stored objects, thereby reducing yellowing, embrittlement, and loss of readability.

Typical characteristics and production approaches include using alkaline or neutral processing rather than acidic pulps, removing or limiting lignin content, and often buffering the material with alkaline substances such as calcium carbonate to create an alkaline reserve. Many säurefrei items carry a label indicating a pH-neutral (around pH 7) or slightly alkaline environment. The emphasis on buffering helps maintain stability even if minor acid exposure occurs later.

Standards and testing vary by country and application. In general, the designation implies low acidity as determined by pH measurements of aqueous extracts, often with additional criteria related to lignin content and absence of residual acid-forming substances. For archival needs, stricter criteria may apply, including long-term stability under typical storage conditions.

Applications and limitations include use in libraries, museums, and private archives for paper, photographs, books, storage boxes, tissue paper, and protective sleeves. It is important to note that säurefrei does not guarantee immortality; environmental factors such as light, humidity, and temperature, as well as the presence of acidic adhesives or coatings, can still affect preservation.