15 March 2025
The preservation of historic paper is a critical aspect of cultural heritage conservation. A new study, recently published on the GREENART website, delves into the chemical processes that drive the degradation of cellulose in historic paper, offering valuable insights for conservators worldwide.
The research reveals that the acidity of historic paper, a key factor in its preservation, is largely influenced by the accumulation of non-volatile carboxylic acids during degradation—most notably oxalic acid. This acid plays a dominant role in accelerating acid-catalyzed hydrolysis, a process that compromises the paper’s structural integrity.
By analyzing 89 European paper samples dated between 1844 and 1990, the study establishes a clear link between paper composition, particularly lignin content, and the production of oxalic and formic acids. Multivariate data analysis demonstrates that lignin significantly contributes to acid formation, highlighting the importance of paper composition in understanding degradation processes.
Key findings from the research include:
- Oxalic Acid’s Influence: Identified as the acid with the highest concentrations and the strongest impact on paper pH.
- Rate of Degradation: The content of oxalic acid increases by approximately 0.01 mmol/g per year, resulting in a pH decrease of 0.008 per year (assuming other variables remain constant).
- Innovative Tools: The development of a portable, non-invasive Raman spectroscopic method to determine lignin content in historic paper.
These results advance our understanding of the chemical dynamics behind paper degradation and provide practical tools for conservators to assess and mitigate these effects.
