Under the spotlight: A new tool (artificial light radiation) to bleach paper documents

• Published in: Journal of cultural heritage 2021-11, Vol.52, p.184-191
• Main Authors: Pérez, Ana Reyes, Arias, Teresa Espejo, García, María Rosario Blanc, Escolano, Amparo, Hernández, Nuria Gómez
• Format: Article
• Language: English
• Subjects: Artificial light radiation; Bleaching; Calcium hydroxide; Hydrogen peroxide
• ISSN: 1296-2074
• DOI: 10.1016/j.culher.2021.10.005

•Artificial light radiation is a viable tool for paper documents bleaching.•Artificial light bleaching does not produce any physico-chemical change in paper.•Artificial light bleaching reduces the yellowing of paper in short and long term.•Paper is physico-chemical and optically deteriorated by hydrogen peroxide. This study offers a new tool to restorers to bleach paper documents: artificial light radiation (ALR). It is a controlled method that is an alternative to other highly aggressive procedures that have been applied to cellulose based media. Its main novelty is its intrinsic lighting characteristics which guarantee uniformity and avoid heating the paper. The results of testing this new tool were compared to those of bleaching with hydrogen peroxide (H2O2). Each of the two methods was applied to five different types of widely used paper: Arches and Somerset (brands serving for engraving and digital printing), Ingres (drawing), press-type (magazines and newspapers) and Bible-type (historical documents). Once characterised by physico-mechanical, chemical and optical parameters (grammage, thickness, specular gloss, optical properties, air permeance, tensile properties, determining the pH of both surface and aqueous extracts), the different papers were bleached by the two methods according to pre-established criteria. Finally, to determine the evolution and effects of the two treatments, the papers were subjected to accelerated ageing.