X-Ploring X-Rays

By Madelyn McKinney and Andrew Kracinski

The Maryland Archaeological Conservation Laboratory (MAC Lab) has, for many years now, explored the uses of radiography (the imaging technique that produces x-rays) in archaeological artifact curation, conservation, and research. Available online, Sarah Rivers Cofield and Nichole Doub’s An Archaeologists Guide to X-Radiography at the Maryland Archaeological Conservation Laboratory (2020) is an easily accessible resource detailing the MAC Lab’s procedures and findings related to radiography. This guidebook describes the process of planning, taking, and analyzing x-rays—informing readers about x-ray settings, accommodations for various levels of artifact corrosion and preservation, and the incorporation of radiography usage into project plans and budgets. Excitingly, the guidebook is filled with photographs and x-rays of a variety of artifacts: ferrous blobs that were discovered to be clothing hooks or scissors; reliquary pendants and locks with interesting internal details; pistols and muskets still loaded with ammunition; and of course, large assemblages of ferrous nails (which sometimes turn out to be more exciting than expected!). 

The main point that the MAC Lab guidebook makes is this: radiography is cheaper, easier, and more accessible than most archaeologists realize––meaning that it has amazing potential for aiding in cataloging and identifying ferrous metal artifacts that may otherwise be overlooked or disregarded. After learning about radiography in this way, a few of our CAP fellows decided to put its accessibility to the test––would we be able to gain access to a radiography machine (and the training necessary to use it) on campus? And if so, would we be able to learn anything new about CAP’s collections from it? 

The answer to the first question, as you might expect given this blog post’s topic, is yes! Starting in the Summer of 2025, two of us CAP fellows began working with the MSU Forensic Anthropology Lab (MSUFAL), where we received training, from Dr. Carolyn Isaac, in using an x-ray machine. The training consisted of two major components: an online “Clinical X-Ray Radiation Safety” module as well as an in-person “Site-Specific Safety Training.” The online training was broad, focusing on the hazards inherent in radiological work, while the site-specific training taught us about actually operating the machine and adjusting its settings based upon our needs. After completing our training, we each received a dosimeter badge: a small device that tracks how much radiation exposure a person experiences while working with x-ray machines or other substances that emit radiation. These ensure our safety––and are also a satisfying material symbol of the training we underwent in order to delve into this project.

We should probably take a moment to explain the reasoning behind using radiography on metal artifacts. In archaeological contexts, metal artifacts often rust over by the time that archaeologists uncover them in the field. While this rust can preserve the general shape of the object (and often times the object itself), it can also lead to the misidentification of artifacts during lab analysis. For instance, we may say that a ferrous metal object is one thing (like a nail), when in reality it is a completely different object. An additional concern is the fact that archaeologists generally collect more items than they actually need, presenting storage problems. For example, not every nail collected needs to be stored in a collection, especially if there are already many examples of that specific type of nail within the collection. X-raying the ferrous metal objects can help solve both of these problems by revealing what an object is––which then informs and impacts our conservation and collection efforts. 

After learning how to use the x-ray machine safely (and doing the MSUFAL lab safety training), we began examining a variety of metals––from nails to a squeegee (see Figure 1)! Since the artifacts we examined had already gone through lab analysis in our CAP lab, we mainly used this as a baseline for learning the methodology needed for examining the metal artifacts. That said, we nonetheless learned a few things about the objects that we have in our collection, from their metal compositions to their actual identities.

With the advice and assistance of Dr. Samantha Ellens (Archaeological Collections Manager at the MSU Museum), we also x-rayed a few artifacts from the MSU Museum’s collections during our preliminary trials with the x-ray machine. Two of these were historic firearms that had never been x-rayed to ensure that they were empty of ammunition, as they were encrusted with rust and recovered from an archaeological context. Our main goal in examining them, therefore, was to make sure that they were unloaded and posed no hidden danger to our museum staff. Fortunately, both were empty––and they allowed us to gain an interesting look into the internal components of these items. 

While we have figured out the most pressing issue of discovering the proper settings on the x-ray machine for the types of artifacts we are examining (as each object type, density, and shape is different), a few problems with the collection have complicated our results. Ideally, x-raying metal artifacts for conservation purposes should take place before they enter a collection and receive any touch ups in the lab. Because all of the objects that we analyzed have already been through the cleaning process, we have not been able to test the full potential of using radiography on the CAP collection. That said, we hope to use artifacts from future field seasons as a test to further prove the utility of this methodology. Stay tuned for future updates!