The Mariners’ Museum and Park explores maritime history using digital X-ray imaging

23/02/2024

The Mariners’ Museum and Park in Newport News, Virginia, USA, is home to the Batten Conservation Complex and the USS Monitor Center. 

Within the Batten Conservation Complex, conservators specialising in archival documents, paper, objects and archaeological materials work alongside a research scientist to stabilise and preserve the collection for generations to come. Researchers across the team continue to build the body of knowledge gleaned from the collection, uncovering the full stories that include the contributions of all cultures to a shared maritime heritage.

As part of this important conservation and research effort, the Mariners’ Museum recently acquired a Dürr NDT 
HD-CR 35 computed radiography system and D-Tect X software to replace much of its existing radiography capability, improving efficiency and flexibility. The HD-CR 35 is said to be the most flexible and advanced computed radiography scanner on the market today, with the ability to provide the highest resolution images in the industry. In addition, due to its unique TreFoc technology, which offers an adjustable laser spot size, it can also provide high-contrast images when necessary.

As an example of how digital imaging helps in the analysis of artefacts, a copper-alloy pocket compass from a dispatch box made in 1872 was X-rayed at a single energy. The imaging plate was then scanned into the Dürr NDT D-Tect X software. Using the powerful image adjustment tools built into the software, it was possible to focus on different density areas of an object without using multiple exposures, as would typically be necessary with film radiography.

	A Dürr NDT HD-CR 35 (left) and D-Tect X software (right) showing a radiograph of the stern of a builder’s half model

The first image highlights the thicker areas of the compass, such as the body and the hinge, while the delicate engraving on the much thinner lid can be seen in the second view. This is the same captured image in both cases, with a minor adjustment in the software viewing parameters to pick out details in the area of interest. As a result of this flexible imaging capability, conservators can use the same image to look at tool markings in the engraving and structure/assembly. Previously, two images would have been 
required.

	Digital images of a pocket compass from a dispatch box

The X-ray image of a leather shoe sole was retrieved from the Princess Carolina, a derelict ship used as fill during land expansion in Manhattan, USA, in the mid-18th century. Although the vessel is earlier, representing the oldest-known European-style ship constructed in North America, the fill material, such as this shoe, dates to the end of the vessel’s life in the mid-18th century. This object is of interest for two reasons: firstly, because it showcases the ability of the HD-CR 35 to image thin organic objects as well as those made of more dense materials such as metal; and secondly, because this X-ray image clearly shows the initials scratched into the leather, which were not readily visible when the sole was examined visually. The image processing filters in the D-Tect X software greatly enhance the contrast of the image to make these details stand out and facilitate the examination and analysis of such valuable artefacts.

A model boat, built by a prisoner of war circa 1801, has a wooden structure with bone overlays and detailing made of bone, baleen, iron and other materials. Many of these materials would have been salvaged from food remains and models of this type were often built to sell, allowing the maker to supplement their meagre rations. Digital X-ray imaging confirmed a suspected internal spring mechanism that originally allowed the cannon to be deployed or retracted, imitating the firing of a broadside and running out the guns. The mechanism has not been activated recently for fear of causing damage, but the X-ray images will be used to further evaluate its condition and to locate missing cannon that may have fallen inside the model.

	Leather shoe sole from Princess Carolina infill material

Another ongoing project at the Mariners’ Museum and Park is the detailed conservation, analysis and documentation of USS Monitor, the first iron warship in the US Navy and the first warship in the world commissioned with a rotating gun turret. The vessel sank off Cape Hatteras, North Carolina, USA, in 1862. Its wreck was discovered in 1973 and the turret was recovered in 2002. All materials recovered are undergoing conservation at the museum, representing the world’s largest marine archaeological metals conservation project.

Many objects from USS Monitor and other vessels have been X-rayed and studied at the Mariners’ Museum. 
Will Hoffman, Director of Conservation, and the conservation team routinely use the HD-CR 35 and D-Tect X software to provide detailed information about artefacts, revealing valuable insights into maritime history. Each conservator is trained to use the equipment and can study their own material speciality. 

Erik Farrell, Senior Objects Conservator, commented: “We are incredibly happy with the image quality we are getting from the HD-CR 35. This new system is helping us learn more about the construction and condition of a wide range of objects and has also vastly simplified our imaging process.”

Founded in 1930, the Mariners’ Museum and Park is an educational, non-profit institution accredited by the American Alliance of Museums, dedicated to preserving and interpreting maritime history through its collection of ship models, paintings and other artefacts. 

www.duerr-ndt.com

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