Author Archives: danagilmore2

Patent (identification) Pending…Gold Coast Wreck Recording Project

Flinders Maritime Archaeology Field Practicum
By Dana Gilmore

The recent Flinders Maritime Archaeology Field Practicum at Gold Coast presented my fellow students and me, along with an array of archaeological professionals, the opportunity to participate in many exciting works and discoveries. One research ‘discovery’ that was particularly exciting was locating several Muntz metal patent stamps. Muntz metal is a specific type of metal alloy—60% copper, 40% zinc—that was used to make sheathing for ship hulls in the 19th century. Muntz or other metal patent stamps were impressed on each sheet of sheathing, and may prove useful for dating the production of the sheathing. This is exciting, since such a date could potentially pinpoint the date of the corresponding shipwreck, which, in our specific case, would help us determine whether the remains thought to be from Coolangatta actually are part of that wreck, or if they come from another, most likely Heroine. Helping to solve this long-standing question was the primary objective of our practicum work, and would be a much welcomed outcome to the local community of Coolangatta.

Muntz 2014_07_15_K103

Fig. 1: Muntz metal patent stamp located on a fragment of sheathing on the Coolangatta memorial in Queen Elizabeth Park (Photo: Lauren Davison, 2014, enhanced with Photoshop).

The team located two circular Muntz metal patent stamps on two separate sheets of sheathing on a section of hull believed to be from the Coolangatta wreckage and now mounted as a monument in Queen Elizabeth Park. The two are different in size and preservation, as one (Fig. 1) is visible on the bottom corner of sheathing exposed to the elements, while the other (Fig. 2) is situated behind the modern commemorative bronze plaque and is highly corroded. We recorded each stamp with sketches and photographs, and performed some preliminary researched on their significance during the practicum.

Muntz K112

Fig. 2: Muntz metal patent stamp found under the commemorative plaque on the Coolangatta memorial in Queen Elizabeth Park (Photo: Lauren Davison, 2014, enhanced using Photoshop).

Three more Muntz metal patent stamps (Fig. 3) were found on sheathing on a monument believed to be from Coolangatta at another location. Unfortunately, these stamps are even more eroded than the two from the park memorial. Nonetheless, each stamp was properly recorded, as additional details might be gleaned from later study or by enhancing the photographs using Photoshop® software. The number of patent stamps we found on a relatively small sampling of sheathing was especially exciting, but, as all the patents are highly eroded, we were unable to make a definitive identification before the weeklong practicum came to an end.

Day 3 patents

Fig. 3: Muntz metal patent stamps found on sheathing (Photo: Lauren Davison 2014).

Recording the stamps for future examination is critical, but proved quite challenging. We cleaned the stamps with a soft-bristled toothbrush and water before sketching and photographing them. Multiple photographs of each stamp were taken at different angles and under different lighting in order to tease out as much detail as possible. We also used chalk to highlight the stamp details. This method worked well for enhanced photographic recording, but failed to reveal any additional details beyond what was visible. I had hoped to be able to overlay photographs of each patent stamp in order to match the stamps and fill in the eroded or otherwise obscured areas, thus ‘creating’ a complete stamp. Unfortunately, not only are all the stamps extremely worn, but they also are particularly damaged in the same area (lower right), thus thwarting these efforts.

Once back in camp, we used digital photo editing software to enhance our photographs and better highlight stamp details, but our efforts again met with limited success. We still were unable to decipher all of the numbers and lettering on the stamps, and may have to resort to specialised software designed to enhance micro reliefs of surfaces.

We also made rubbings of each stamp (Fig. 4), experimenting with paper of varying weight and pencils of different hardness in our attempt to capture as much detail as possible. Unfortunately, the rubbings were only able to capture the same level of detail as was visible to the naked eye.


Fig. 4: Dana Gilmore makes a rubbing of a Muntz metal patent stamp (Photo: Lauren Davison 2014).

Our preliminary research on the patent stamps revealed that the central number on the stamp indicates the sheathing plate thickness gauged by weight. In the case of one of the patent stamps we recorded, the sheathing therefore was 18 gauge, or 18 oz./ft2. Above and below the gauge number, in the outer ring of the stamp, are the words “MUNTZ’S PATENT”, and to either side is a number (typically the same number), the meaning of which is not yet known (Fig. 5). All of the patent stamps we found on the preserved sheathing are highly eroded and initially we were unable to make out all of the stamp numbers. We took one sample fragment of sheathing that is stamped in order to have it conserved so that hopefully we will be able to read the stamp numerals.

In addition to the stamps themselves, we also took metal samples of each piece of sheathing for detailed elemental and metallurgical analyses. The results of these tests undoubtedly will provide additional evidence with which to date and identify the ship remains. It will also be useful to examine the Muntz manufacturing records and identify, if possible, what stocks of Muntz sheathing were exported to New South Wales in the 19th century and potentially used in the constructions of Coolangatta and Heroine.

Muntz book

Fig. 5: Examples of Muntz and other metal patent stamps (from McCarthy 2005: 115 Fig. 73).

Although the discovery of Muntz metal patent stamps during the practicum fieldwork initially proved inconclusive, the recording, sampling, and field research of the hull sheathing and patent stamps provided me an excellent opportunity to learn different archaeological recording techniques, such as rubbing, sketching and photography. They also impressed on me the difficulties of dealing with poorly preserved artefacts and the need to apply multiple recording techniques in order to maximise the amount and quality of data collected. The discovery of the Muntz metal patent stamps and subsequent field research was exciting and educational, demonstrating the value of careful examination and recording, as well as the need to do preliminary research while still in the field. Overall, I found the practicum experience—especially the work on the patent stamps—rewarding because it exposed me to the real challenges of conducting archaeological work in the field, recording and analysing archaeological material re-used in contemporary art and monuments, and studying artefacts that have not been properly conserved or are exposed continuously to the elements. My week in Gold Coast certainly sparked an interest in me to learn more about the conservation of artefacts and, in particular, ways to halt or reverse the environmental degradation of artefacts that are displayed outdoors.

McCarthy, M. 2005. Ships’ Fastenings: From Sewn Boat to Steamship. Ed Rachal Foundation Nautical Archaeology Series. College Station: Texas A&M University Press.