Handheld FTIR analysis for the conservation and restoration of fine art and historical objects

Importance of the Topic

FTIR spectroscopy offers sensitivity, specificity and non-destructive analysis, crucial for conservation, restoration and authentication of paintings, manuscripts, sculptures and historical objects. Handheld FTIR analyzers extend these capabilities to in situ measurements without sample removal, preserving the integrity of valuable artifacts.

Objectives and Study Overview

This application note describes the use of Agilent 4100 ExoScan and 4200 FlexScan handheld FTIR systems to analyze pigments, binders, coatings, glues and materials in historical and archaeological contexts. Key aims include demonstrating non-destructive assessment of aging, cleaning processes, authenticity markers and firing temperatures for heritage objects.

Methodology and Instrumentation

• Agilent 4100 ExoScan and 4200 FlexScan handheld FTIR analyzers with performance equivalent to benchtop systems
• Sampling accessories: diffuse reflectance probe for non-contact surface analysis
• Spherical ATR accessory for glue and pigment library matching

Main Results and Discussion

• Oxalate accumulation on painted temple doors revealed microbial degradation levels via diffuse reflectance spectra, distinguishing red and black regions by oxalate intensity
• Evaluation of cleaning on a 17th century painting showed baseline shifts from dirt and silicate removal monitored in real time
• Glue residues in archaeological pottery and manuscripts were classified as animal-based or synthetic by characteristic amide and carbonyl bands
• Identification of natural pigments and dyes (Tyrian purple, carmine, alizarin, indigo) overcame fluorescence issues common in Raman methods
• Firing temperature of Orkney clay shards determined by spectral changes in OH regions, correlating sample spectra to reference clays heated from 200 °C to 800 °C
• Monitoring of UV-stabilized polymer coatings on large outdoor murals planned by following carbonyl band changes to schedule restoration

Benefits and Practical Applications

• Non-destructive, in situ analysis of immovable or fragile art and artifacts
• Minimal equipment footprint and flexible orientation for ceilings, caves and curved surfaces
• Real-time spectral scanning to locate areas of interest before detailed measurement
• Library search and material identification at remote sites without laboratory access

Future Trends and Opportunities

Handheld FTIR will benefit from expanded spectral databases for cultural heritage materials, integration with portable Raman or XRF methods, and remote connectivity for cloud-based analysis. Advancements in data processing and AI could enable automated identification of degradation patterns and predictive maintenance scheduling for outdoor murals and historic structures.

Conclusion

Handheld FTIR analyzers such as Agilent 4100 ExoScan and 4200 FlexScan provide high-quality, non-invasive chemical analysis essential for conservation, restoration and authentication of fine art and historical objects. Their portability, versatile sampling options and real-time capabilities support informed decision making without disturbing precious heritage materials.

Reference

Rein A, Higgins F, Leung PT. Handheld FTIR analysis for the conservation and restoration of fine art and historical objects, Agilent Technologies Application Note 5990-8739EN, 2015.