This lesson explores the presence of strontium in art materials and its significance in the analysis of paintings. While strontium is primarily associated with the modern pigment strontium yellow, it is also found in trace amounts in chalk and gypsum, materials commonly used in ground preparations for paintings. Understanding the role of strontium and its X-ray fluorescence (XRF) spectrum is crucial for interpreting data in the study of artworks.
Objectives
- Identify strontium yellow as a modern pigment and understand its composition.
- Recognize the presence of strontium in chalk and gypsum and its role in ground preparation layers.
- Interpret the XRF spectrum of strontium, focusing on its characteristic X-ray lines.
- Understand the substitution of calcium by strontium in mineral structures.
Materials
- Pigments Checker (containing strontium yellow, chalk, and gypsum samples).
- XRF spectrometer.
- Periodic table for reference.
Lesson Plan
- Introduction to Strontium in Pigments
- Discuss the modern pigment strontium yellow (strontium chromate) and its unique characteristics.
- Highlight the significance of strontium yellow in the Pigments Checker.
- Strontium in Chalk and Gypsum
- Explain the natural occurrence of strontium as a trace element in chalk (calcium carbonate) and gypsum (calcium sulfate).
- Describe the geological variability of strontium content in these materials.
- XRF Spectrum of Strontium
- Introduce the characteristic X-ray lines of strontium (Kα at 14.1 keV and Kβ at 15.8 keV).
- Present the XRF spectrum of strontium yellow as a baseline for identifying strontium.
- Chemical Substitution in Minerals
- Use the periodic table to explain how strontium can substitute for calcium in mineral structures due to their similar electronic configurations.
- Relate this substitution to the trace presence of strontium in chalk and gypsum.
- Application to Art Analysis
- Discuss how strontium signals in XRF analysis provide insights into the ground preparation layers of paintings.
