Reflectance Spectroscopy for Palimpsests (1h)

Through this lesson, students will learn how to leverage reflectance spectroscopy, to choose the best filters and strategies for reading obscured texts with a multispectral imaging examination. Objectives

• Gain practical experience using a spectrometer to measure reflectance spectra of different inks and supports.
• Develop a strategy for multispectral imaging that maximizes the contrast between inks and supports.

Materials

• Reflectance spectrometer (GORGIAS or similar)
• Mock-up palimpsest with iron gall and carbon inks

Lesson Plan   1. Overview of Reflectance Spectroscopy

• Explain the basics of reflectance spectroscopy and its applications in art examination.
• Show how reflectance spectra can guide the selection of filters for multispectral imaging.

3. Demonstration: Acquiring Reflectance Spectra

• Use the reflectance spectrometer to measure spectra from the mock-up palimpsest, focusing on three key areas: the parchment support, iron gall ink, and carbon ink.
• Demonstrate how to maintain consistent probe angles and distances for accurate measurements.

  4. Planning a Multispectral Imaging Examination

• Discuss how the reflectance spectra guide the selection of optimal filters from the multispectral imaging system.
• Identify the filters that maximize the contrast between the iron gall ink, carbon ink, and the support.