Klucel Hydroxypropylcellulose : (Its Impact on Artificial Ageing and Consequences for Conservation Usage – A Case Study)

Hydroxypropylcellulose (HPC) was classified as an unstable polymer in the 1990s, but it has been used as an adhesive, consolidant, poultice and coating for more than 50 years without major negative effects. This leads to questions regarding the design of artificial testing protocols and the interpretation of their results. In this study, Klucel G was dissolved in water and organic solvents such as ethanol and butanol. The film sheet samples were heat aged for 30 days at 40°C, 70°C, 90°C and 110°C. Visual assessment, light microscopy and scanning electron microscopy as well as colour measurements were performed weekly. The film sheets from HPC dissolved in organic solvents were less resistant to thermal degradation than were the film sheets from HPC dissolved in water. At temperatures < 100°C, the sensitivity to thermal degradation was low. Key factors included the solvent used for the preparation and the established temperature. The final concentration applied for conservation treatment must also be considered and should be as low as possible.