Model predicts ’shelf life’ for library and archival collections

Heritage scientists at UCL have developed demographic models of decay and loss to predict when a large library or archival collection might age beyond repair. Lead author, Professor Matija Strlic (UCL Institute for Sustainable Heritage) explained: "Although some library materials might easily survive thousands of years some have internal clocks triggering faster decay. Using the demographic models we can now easily predict how much more degradation will be induced by a hotter and more humid climate in the future, and perhaps more importantly, how this can be mitigated." The three part report 'Damage Function for Historic Paper' published today in Heritage Science explores what makes an historical paper unfit for use, the degradation of historical documents due to handling, and how heritage resources can be managed and stored with more economical and environmental sustainability. The team developed an equation describing how the length of cellulose, the dominant macromolecule in paper, decreases with time depending on the acidity of paper and the environmental conditions during storage. Another model described how wear and tear accumulates with instances of reading of a book or an archival folder. The scientists looked at more than 600 historic documents from all over Europe to arrive at a general demographic model describing how ageing progresses and fitness is lost. Professor Strlic said: "We considered a heritage collection as a population of people and used census methods and ageing models to predict how a large library or archival collection might age beyond repair.