Moisture dynamics in wall paintings monitored by single-sided NMR

Area of Science:

• Art Conservation Science
• Materials Science
• Geophysics

Background:

• Historic wall paintings face degradation from environmental factors like moisture and salt.
• Understanding dynamic transport processes is crucial for effective conservation.
• Non-invasive techniques are needed to assess the condition of delicate cultural heritage.

Purpose of the Study:

• To evaluate the efficacy of Nuclear Magnetic Resonance (NMR) MOUSE(®) for monitoring moisture and salt crystallization in wall paintings.
• To correlate salt crystallization, moisture transport, and diffusion using experimental and modeling approaches.
• To assess the impact of painting techniques and conservation methods on material properties.

Main Methods:

• Utilized a mobile, single-sided NMR sensor (NMR-MOUSE(®)) for non-invasive measurements.
• Conducted experiments on wall painting samples to study moisture and salt dynamics.
• Employed computational modeling to analyze transport processes and diffusion constants.
• Performed field measurements on real fresco paintings in Herculaneum, Italy.

Main Results:

• The NMR-MOUSE(®) successfully monitored moisture content, transport, and apparent diffusion constants.
• Established correlations between salt crystallization, moisture transport, and local diffusion.
• Demonstrated the influence of different painting techniques (fresco, secco) on moisture dynamics.
• Observed the effects of conservation/consolidation treatments on material behavior.

Conclusions:

• Non-invasive NMR-MOUSE(®) is a valuable tool for assessing the condition and dynamic processes in historic wall paintings.
• The study provides fundamental insights into moisture and salt transport, informing conservation strategies.
• Results from laboratory studies align with field measurements, validating the technique for real-world applications.