Zinc has played a pivotal role in the development of pigments, particularly as a safer alternative to poisonous lead white. In this lesson, we will explore two key zinc-based pigments—zinc white and lithopone—focusing on their composition, historical significance, and detection using XRF analysis.
Objectives
- Understand the historical significance of zinc-based pigments as replacements for lead white.
- Identify the composition and characteristics of zinc white and lithopone pigments.
- Analyze XRF spectra to distinguish zinc signals from these pigments.
Materials
- Pure zinc cube for baseline testing.
- Pigments Checker Standard containing zinc white and lithopone samples.
- XRF spectrometer with routine filter setup.
Lesson Plan
- Introduction to Zinc-Based Pigments
- Discuss the historical context of zinc white and lithopone as safer alternatives to lead white.
- Highlight the composition of zinc white (zinc oxide) and lithopone (zinc sulfide and barium sulfate).
- Analyzing Pure Zinc
- Use the XRF spectrometer to examine the spectrum of a pure zinc cube.
- Examining Zinc-Based Pigments
- Analyze the XRF spectra of zinc white and lithopone samples from the Pigments Checker Standard.
- Discussion of Results
- Discuss how the presence of barium in lithopone affects zinc signal intensity.
- Highlight the reliability of XRF analysis for identifying zinc-based pigments, even in small concentrations.
