Barium is a common element encountered in the analysis of paintings, because its main pigments, barium sulfate and lithopone, are used for canvases’ ground preparation and as pigments’ extenders and fillers.
Objectives
- Understand the role of barium sulfate in pigment and ground layer preparation.
- Recognize the spectral features of barium, including K and L lines, in X-ray fluorescence (XRF) analysis.
- Differentiate between pure barium sulfate and its mixtures, such as lithopone.
Materials
- Pigment samples containing barium sulfate and lithopone as in Pigments Checker STANDARD and MODERN ART.
Lesson Plan
- Introduction to Barium in Art Materials
- Discuss the historical use of barium sulfate as a white pigment, ground layer component, and pigments’ extender.
- Highlight the significance of lithopone as a safer alternative to lead white in the 19th century.
- Analyzing Spectral Characteristics
- Examine the XRF spectrum of barium, focusing on K alpha and K beta lines.
- Discuss the complexity of K alpha peaks due to the presence of K alpha 1 and K alpha 2.
- Introduce L lines for heavy elements and their relevance when K lines exceed detector limits.
- Case Study: Lithopone Spectrum
- Compare the spectra of pure barium sulfate and lithopone, emphasizing the contributions of zinc sulfide and barium.
