Properties of lignocellulosic packaging materials for the long-term storage of diazotype records in depositories

Abstract This study evaluates the suitability of selected lignocellulosic papers as packaging materials for the long-term preservation of diazotype records. To assess possible packaging materials, five types of paper were tested under artificial ageing conditions that simulate long-term storage. Their optical, chemical, and mechanical properties were systematically analysed. The results revealed that two tested alkaline papers exhibited high optical and mechanical stability, alkaline pH values, and limited release of harmful volatile organic compounds. Whatman No. 1 unsized paper showed good optical stability and chemical neutrality. Two types of acidic paper sized with rosin performed poorly, releasing volatile acids and displaying low mechanical resistance. In general, both alkaline papers are recommended as packaging materials for the preservation of the diazotype, while Whatman No. 1 represents a possible compromise. Acidic papers are unsuitable because of their acidity, the emission of harmful degradation products, and their insufficient durability.