About XRF
XRF is an elemental (or chemical) analysis technique in which the painted surface of the artifact is hit with an X-ray beam. The beam causes electronic transitions within the atoms of painted areas on the artifact, a phenomenon that can be measured and recorded as a spectrum. The spectrum is used to determine which elements are present in the paint.
Our Setup Includes:
- Bruker Tracer 5g handheld XRF unit (Bruker—also available to rent)
- A camera tripod—although the instrument is designed to be handheld, we opted to attach it to a tripod in order to distance ourselves from the instrument while conducting the survey (we purchased an Oben tripod from Bruker, which supplied the necessary adapter for the instrument)
- Software interface for remote instrument operation—we prefer ARTAX software to other Bruker programs (included with XRF unit)
- Dosimeters and radiation exposure monitoring for each user. These may or may not be required by users’ institutions or local jurisdictions; check with your university’s or state’s environmental health and safety office. Dosimetry services are available through companies such as Landauer, which provides badges, analysis, and reports
Our laboratory’s spectrometer is a Bruker Tracer 5g handheld XRF unit, and the following workflow is written for this spectrometer.
- Note: Similar handheld instruments include the Thermo Niton series and the Olympus Vanta—all can be made with acquisition parameters that are suitable for pigment analysis
Additional Considerations
XRF can help ID pigments that contain heavy metal ions like copper, iron, and lead, but it can’t really identify the types of compounds most organic dyes are made of. Certain elements (like iron) are found in burial dirt and other contaminants, which can obscure results.
Helpful Hints
- XRF is useful for technical survey, especially when studying a range of artifact types in different locations because you can bring the instrument to the object
- Consider purchasing an XRF stand, platform, and lid if you plan to analyze small (coin-size) objects and a backing plate if you want to analyze materials on textiles