A First at the Freemasons Hall

By Sarah-Anne Martin

This semester I have had the privilege of working on a Directed Study project with Curator Murray Olsson and the volunteers at the Adelaide Masonic Centre Museum, which can be found within the Freemasons Hall, 254 North Terrace, Adelaide. I have been volunteering on and off at the museum for well over a year now and have had some fantastic opportunities presented to me as a result. From the outset one might be forgiven for feeling somewhat intimidated by the Freemasons Hall, after all it is a very large building which belongs to what is considered to be a very exclusive and secretive group: The Freemasons. However, if you ever get the chance to take a tour of the Freemasons Hall you will see that this feeling is misplaced, as the building alone is incredible but the people are also friendly and happy to answer any questions you have about their organization.

grand lodge

Figure 1. Adelaide Freemasons Hall (Source: Freemasons South Australia and Northern Territory)

The museum, found on the ground floor of Freemasons Hall, is packed to the brim with memorabilia and artefacts from the practice of Freemasonry in South Australia and the Northern Territory. Up until recently the museum did not have an official program for cataloguing its collections, apart from excel spreadsheets, but after receiving a grant from History SA the museum has begun to embark on the colossal task of setting up its catalogue. This is where I come in. Having been the person to submit the grant and begin the process I have been set the task of cataloguing a collection under the direction of the curator Murray Olsson, and using the things I learn as a basis for future cataloging projects. This is no small feat and is a task that has been a tremendous learning opportunity for me.

My Directed Study project focuses on cataloguing the Museum’s collection of Past Masters Jewels, which consists of over 300 individual objects. The Past Masters Jewels collection provides a record of the men who have served the organization as a Master in one of the many lodges in South Australia. Each Past Masters Jewel has a unique inscription stating the name of the recipient and the date of service, providing a very clear historical record of each jewel. In addition, the collection holds jewels from as early as the late 1800s, many of which are gold, making the collection highly significant and a priority for conservation, protection and maintenance. It is certainly a privilege to be working with such an amazing collection and to gain further insight into a very historically significant organization.

pm jewels

Figure 2. A small part of the Past Masters Jewel Collection at Adelaide Masonic Centre Museum.

The Bootu Creek Manganese Mine Decision.

In August of 2013 a Northern Territory court found OM Manganese guilty of the desecration of an Indigenous sacred site. OM Manganese runs the Bootu Creek mine, north of Tennant Creek in the Northern Territory. This was the first time that the charge of desecration had been successfully prosecuted in an Australian court, and the decision will be the subject of debate for a long time to come.

One aspect that particularly struck me was that Magistrate Sue Oliver said in her decision that “In my view the offence created by section 35 of desecration of a sacred site was intended to go to the heart of what was recognised by the legislation, that is, the sacred or spiritual nature of a site. If that character should be insulted, diminished or removed, it may interfere with or cause to be lost, the belief systems associated with a site including damaging the sacredness of the site.” (Oliver 2013) This means that intent to desecrate a site is not necessary to be found guilty if, by their actions, the party had damaged the spiritual or sacred meaning of the site.

This has huge implications for the heritage industry. Usually criminal actions are at least partially defined by the intent to commit a criminal act. Magistrate Oliver found that in the case of desecration intent is not a factor, only results. Heritage professionals now have duty to protect not only the physical aspects of a site, but also the sacred/spiritual aspects of the landscape from detrimental activities.

During the course of the Practicum that I have been undertaking at Australian Cultural Heritage management Pty Ltd it has become apparent that changes in heritage legislation and case law has a profound impact on how archaeologists work. Currently most archaeological work in South Australia and Western Australia is limited to survey and assessment, as this is all that the law requires. This decision has the potential to cause both governments and mining companies to dramatically revise the role of archaeology in their decision making process, and the place of Traditional Owners in decisions about sacred sites.

Map showing the location of the Bootu Creek Mine http://www.resourcesroadhouse.com.au/_blog/Resources_Roadhouse/post/Bligh_Resources_to_acquire_more_NT_ground/

The Domestic life: The Lady Alice Mine

Image

It is nearing the end of the semester and the blog posts are drawing to an end, but luckily this is not the last. The Lady Alice Mine has opened up my eyes to the life of gold mining in South Australia. While you may not know much about this, or be aware that South Australia had an active gold mining culture (although it was certainly not as successful as that in neighbouring Victoria), South Australian mining was still a successful industry.  I have been extremely lucky to have been able to do some study on this site. The heritage of the area is vast in nature and it would be great if more could be done on this site in order to find out more about not only Hamlins Gully but also about the Barossa Goldfields in general. It would be great if the history of South Australia’s mining culture could be shared with more than just the locals of the area.

The second semester’s Directed Study has focused on the domestic life of the Lady Alice, which is still largely unknown. There are a few photographs and paintings that show the different aspects of the Lady Alice Mine. These show different angles of the mine and how it once operated. They also shed some light on how the miners lived and worked. Nevertheless they give us some insight into the conditions and, having visited the site, allow for the mine to be put into perspective. From these photographs and paintings we are able to see that they miners lived in canvas tents, some of which had brick chimneys at one end. However, as the tents are transportable and were most probably taken with the miners when they left, there is no evidence supporting the photographs and paintings. It would be great if there was more photographic and written evidence of this time, but unfortunately the mine was poorly recorded and only some records survive, which can be accessed at the State Library of South Australia. There is not much information about the domestic life of the mine in these records, as lives were not documented as we’re able to do today. It’s fun to imagine what, if people of the 1800s had all the equipment that we do today to document daily life, we could have learnt.

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(The Globe INN)

When walking through the Lady Alice Mine area it becomes evident how the miners once lived and worked. There are few ruins and even less surface evidence of what types of dwellings they lived in. There are ruins of chimney butts that stand by themselves with no other material. Standing at the edge of a site and imaging what once stood by the sides of the chimneys. It has been an incredible experience to be able to walk through the area and imagine the fields being littered with tents and makeshift dwellings. Unfortunately, I do not have the authority to share the paintings or the photographs as they are not readily available on the internet. One of the two photos that I have shared today is a photograph I took myself and the other was available through http://www.trove.nla.gov.au. Anyway, I must stop imagining all of this and get back to writing my report. Please stay posted for my last post, which will be in just a few weeks.

Romance, scandal and maritime archaeology in Victoria

During my directed study, I’ve been researching 18 shipwrecks lying in Victorian state waters. I’ve researched the history of shipwreck significance, worked out how shipwreck significance is assessed and begun the process of assessing significance for some of those wrecks.

Some shipwrecks have turned out to be significant because of the events surrounding their working lives, some because of the results of the studies of archaeologists examining their wrecks. Either way the waters of Port Phillip and the surrounding Victorian coastline shelter some very interesting shipwrecks.

Here’s just a taste:

Loch Ard is one of the most famous shipwrecks in Victoria. A three-masted square-rigged iron sailing ship, Loch Ard left England on 2 March 1878 with a general cargo of luxury items and industrial loads of railway iron and cement. On 1 June, the ship was only a day or two out from Melbourne near Cape Otway when heavy fog descended.

Loch Ard. Image courtesy Heritage Victoria

Loch Ard. Image courtesy Heritage Victoria

When the fog lifted, the Captain, instead of clear ocean and a distant shoreline, was faced with sheer cliffs and breaking waves. I can’t even begin to imagine what that felt like. The ship hit the reef just off Mutton Bird Island and large waves caused the masts and rigging to crash down so the lifeboats couldn’t be launched successfully. Tom Pearce, one of the crew, and passenger Eva Carmichael were the only two on board who survived (Lomdahl 1992).

Just five bodies (out of 47) were ever recovered. Eva lost all her immediate family and would have died herself if Tom Pearce hadn’t come to her rescue. If life were a Hollywood movie, Eva and Tom, both eighteen, would have sailed happily off into the sunset. Society of the day certainly thought they should at least get married since they had spent time alone, drinking brandy before Tom went to find help (ignoring the fact it was dark, cold and Tom needed to catch his breath before attempting to climb the cliffs). But it wasn’t Hollywood and instead Eva went back to Ireland and married a Captain Townsend while Tom went back to the sea. Ironically, Eva and her husband moved to the Irish coast where she was called on to help shipwreck survivors … one of whom (apparently) turned out to be Tom Pearce (The Argus 16 June 1934). This is a Hollywood script just crying out to be written.

The Loch Ard Peacock. Image courtesy Victorian Collections.

Image courtesy Victorian Collections.

A few days after the wreck, a crate containing a large ceramic peacock was washed ashore in Loch Ard Gorge. The Minton Loch Ard Peacock is one of the more famous pieces of cargo saved from the wreck. The porcelain statue, valued at over $4 million, is one of only nine still existing worldwide and was arriving in Australia to be displayed at the 1880 Melbourne International Exhibition. It finally got its chance to shine at the 1988 Brisbane World Expo. The peacock is currently on display at the Flagstaff Hill Maritime Museum in Warnambool, Victoria.

Then there’s Clarence, a small coastal wooden sailing ship, indistinguishable from many vessels plying their trade around the southern coast of Australia during the 1840s and 1850s. Clarence sailing past would have been a bit like watching a semi-trailer driving down the highway. You might idly wonder what it was carrying before it disappeared from view; then again you might not. However, Clarence’s brief and unglamorous career as a small trading schooner belies its subsequent importance to archaeological and historical studies of undocumented Australian shipbuilding (Harvey 1989).

Clarence line drawing. Image courtesy Heritage Victoria

Clarence line drawing. Image courtesy Heritage Victoria

I’m sure Clarence’s builders from the Williams River in NSW never imagined their work would be so scrutinised. Remember people, whatever you build today may be examined in 200 years by an archaeologist trying to piece together your work … make sure it’s good (or if you want to have some fun, make it cryptic)!

Clarence is currently the subject of an Australian Research Council grant studying the excavation, reburial and in-situ preservation of shipwrecks and their artefacts. I was fortunate enough to be a volunteer when, in 2012, Clarence was excavated, wrapped in geo-textile, covered in shade cloth and tarpaulin and weighed down by 3,500 sandbags. As a result, Clarence may still be there for archaeologists to study in 1000 years time and I can now add ‘professional sandbag filler’ to my resumé.

A small section of Clarence reburial .... Image Jon Carpenter

A small section of Clarence reburial …. Image Jon Carpenter

One vessel not often in the public eye is the clipper ship, Schomberg. Schomberg had no statement of significance in the Victorian database and when I started researching I had no idea what I’d discover. What I did find was a tale of pride, scandal and narrowly avoided tragedy. Schomberg’s story was almost the nineteenth century’s version of Titanic: built at great expense, labeled the most perfect clipper ship ever built, designed to be the most comfortable, luxurious and fastest vessel to sail to Melbourne—and it sank on its maiden voyage in 1855. Fortunately, the steamer SS Queen was close enough to come to the rescue of the 430 passengers and crew.

Captain 'Bully' Forbes. Image courtesty Project Marco Polo

Captain ‘Bully’ Forbes. Image courtesty Project Marco Polo

The Captain, ‘Bully’ Forbes, was charged in the Supreme Court with negligence because of the suspicion that he was playing cards with two female passengers below decks while his ship ran aground. None of the passengers spoke terribly highly of him, complaining that he strutted the deck with a loaded revolver and that half-naked women were emerging from his cabin at all hours of the night. Despite a protest meeting, two inquiries and the court proceedings, he was found not guilty and cleared of all charges on the grounds of insufficient evidence (Uhl 1985:24).

As an aside, Schomberg was built using the ‘diagonal principle’: its frame was British oak with layers of Scottish larch fitted diagonally to the frames, apparently the same design as Queen Victoria’s newly acquired yacht. Interestingly, pieces of hull with this distinctive design feature were washed up on the New Zealand coast and were thought to be a part of Schomberg‘s hull (Lomdahl 1992).

The clipper ship, Schomberg. Photo Heritage Victoria

The clipper ship, Schomberg. Image courtesy Heritage Victoria.

This is just a brief journey through three Victorian shipwreck histories that grabbed my attention, there is more to tell for each but space is brief. While it takes more than just romance, scandal and maritime archaeology to make a vessel significant, each adds to the fabric of the story that makes up the life and wreck of a ship.

References

Harvey, P. 1989 Excavation of the Shipwreck Clarence: Port Phillip Bay October 1987. Victoria: Victoria Archaeology Survey, Maritime Heritage Unit.

Lomdahl, A., 1992 Underwater Shipwreck Discovery Trail. Victoria: Victoria Archaeological Survey, Maritime Archaeological Unit.

Mosely, M. 1934 ‘Eva Carmichael and Tom Pearce. Why they did not marry.’ The Argus (Melbourne, Vic.:1848-1957), 16 June, p. 4, retrieved 13 October 2013, http://trove.nla.gov.au/ndp/del/article/10947161

Uhl, J. 1985 Sailing Ships, Shipwrecks and Crime in the 19th Century: A Handbook for Historians, Genealogists, Shiplovers and Criminologists based on Supreme Court Records, Criminal Sessions 1840s-1860s. Oakleigh, Victoria: Australian Institute of Genealogical Studies.

Underwater Site Photography Methods

Photography in an underwater archaeological setting plays an integral role. It is much more than just simply taking appealing pictures of artefacts and submerged landscapes. Not only is camerawork usage highly practical as a means of recording information on a site, it can be applied in many different aspects in the field. These range from general practices such as illustrated photos of artefacts or work being conducted for public awareness to more technical methods that provide information with which accurate site plans and the analysis and interpretation of finds underwater may be generated. The application of photographic methods, such as creating a photomosaic and photogrammetric techniques, will be discussed below.

Photographic mosaics:

This technique has been used as an ideal tool in site survey methodology since the 1970’s (Finney and Stephen 2005). The main reason mosaics are produced is lack of visibility and clarity under water and/or the size of the site does not enable generation of an overall site photograph (Bowens 2009). As an alternative to such complications, a sequence of photos are taken at a determined range and are then combined or “stitched” together to create a holistic view of the site. The methods of photo production vary and are dependent on the type of two dimensional control used underwater. A control system is required in order to produce a properly scaled mosaic and consists of three elements: 1) a grid line consisting of a series of lines at fixed intervals set up across the site; 2) a grid frame control that uses square graduated frames; and 3) a network-controlled system made up of coordinates along the site (Green 2004). All cameras, whether underwater, digital or video, are attached to specialized equipment such as a photo tower to help prevent tilt. The resulting sequence of photos are produced with an overlap of at least fifty percent to ensure complete coverage of the site. An example of the grid frame control system is presented in Figure 1.

 

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Figure 1. Illustration of photographer using a grid frame control (Bowens 2009: Figure 10.7)

Once all photos are compiled, they go through a process of rectification where each is augmented to the same scale and joined with the others to make one large picture.  In the past this would have been an extremely tedious procedure, but recent technological advances in computer software have enabled the creation of mosaics with programs such as Photoshop (Figure 2). Even though a photomosaic is not a complete site plan, it is still an important tool with which to quickly reference a site. It can also serve as a visual inventory that provides a baseline for future survey work (Finney and Stephen 2005).

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Figure 2. Photomosaic created using Photoshop. (Finney and Stephen 2005: Figure 2)

 

Photogrammetric techniques:

The practice of photogrammetry has been in use almost as long as photography itself (Kucukkaya 2003).  When these techniques are applied in an underwater environment they can be extremely beneficial for maritime archaeologists. Application of photogrammetric techniques can be used at any depth; however, they are especially useful when utilized for deep-water sites, where the amount of time available to conduct conventional survey methods and diver safety both can become factors. These methods essentially produce accurate geometric measurements, where data from multi-viewpoint photographs are manipulated to obtain three-dimensional information (Green 2004). This information is produced through a process called phototriangulation. This method of triangulation is obtained through the use of a calibrated camera that is connected to a computer-modelling program such as Rhino, PhotoModeler, MicroStation, or VirtualMapper. Once the camera is calibrated, measurements are obtained via ray paths that originate from the focal point of the camera, and pass through the photographic image to various points on the site (Green, et al. 2002). A control system must be employed when using these photographic methods to maintain an appropriate scale for the data. There are several ways the images can be acquired. They can be taken in the same way as a photomosaic where, with a designed control system established, a diver takes a sequence of pictures of the site. However, when employing these methods in deep-water environments, the cameras are sometimes deployed from a remotely-operated vehicle (ROV) (Figure 3). Whether an ROV or underwater photographer compiles photographic data, an overlap of at least sixty percent must be maintained for proper coverage of the site.

figure 3

Figure 3. Photograph of ROV used in photogrammetry underwater (Drap, et al. 2007: Figure 2).

After the photogrammetric survey is completed, the data must be referenced with an actual model of the material culture found at the site. Once cross-referenced in this manner, a highly accurate three-dimensional plan can be produced of the entire site (Figure 4).

figure 4

Figure 4. Three dimensional site plan of a large artefact assemblage made from photogrammetry (Drap, et al. 2003: Figure 6).

It is apparent that underwater site photography methods have improved with advances in modern technology. It was not too long ago that photographic equipment was too cumbersome and expensive to be applied on a large scale; now they are easily accessible and produce better, more efficient images with a variety of user-friendly software packages. With the prospect that more insitu survey projects will become the norm in underwater archaeology, the use of methodologies outlined above can serve an exciting future role. Currently photographic methods not only provide accurate site detail, they also can be used as a valuable educational tool. This is particularly true as regards the general public, who may not even be aware of the abundance of human history that lies underwater, and will most likely be destined to remain there.

References:

Bowens, Amanda 2009 Underwater Archaeology: The NAS Guide to Principles and Practice. 2nd ed. Blackwell Publishing, West Sussex.

Drap, P, J Seinturier, D Scaradozzi, and P Gambogi… 2007 Photogrammetry for virtual exploration of underwater archeological sites. XXI International CIPA Symposium, 01-06 October, Athens, Greece

Drap, P, J Seinturier, and L Long 2003 A photogrammetric process driven by an Expert System: A new approach for underwater archaeological surveying applied to the’Grand Ribaud F’Etruscan wreck. Computer Vision and Pattern Recognition Workshop, 1: 1-6

Finney, S. and Stephen, J. 2005 Photomosaics in Shallow Water

Environments: Challenges and Results, Marcet i Barbe, R., Brebbia, C.A.,

Olivella, J., Maritime Heritage and Modern Ports, 195–206.

Green, J., Matthews, S., & Turanli, T. 2002, Underwater archaeological surveying using PhotoModeler, VirtualMapper: different applications for different problems. International Journal of Nautical Archaeology, 31(2), 283-292.

Green, Jeremy 2004 Maritime Archaeology—A Technical Handbook, Academic Press, San Diego.

Kucukkaya, Ayse Gulcin 2004 Photogrammetry and remote sensing in archeology. Journal of Quantitative Spectroscopy and Radiative Transfer 88: 83-88

Aside

Once a maritime archaeological site has been located a pre-disturbance survey is the next step. The aim of a pre-disturbance survey is to record the site as it exists, and collect as much information as possible. This includes, but is not limited to, factors such as the extent (dimensions) of the site, water depth, visibility, physical features (both natural and archaeological) and potential difficulties for future work on the site (such as excavation or monitoring) (Green 2004:87-88). A pre-disturbance survey should accurately and efficiently collect as much information as possible. No matter what type of survey method is employed, the basic principles of accurate position fixing and data recording are consistent on any project (Tuttle 2011:114-115). One of the main products of pre-disturbance survey is a site plan, and there are a number of methods that can be used to generate one. The decision as to what technique to use will depend on a number of factors, such as site condition and the environment (Feulner and Arnold 2005:285; Green 2004:87).  Two ‘low tech’ (but very effective) methods used in the creation of maritime archaeological site plans will be discussed below. These techniques, known as baseline offset (Figure 1) and trilateration surveys, involve the use of datum points, divers and tape measures to plot the location of site features and develop a site plan.

OLYMPUS DIGITAL CAMERA

Figure 1. Recording offset measurements (Flinders University 2013)

A quick ‘mud map’ or sketch provides an overview of the site, and shows its main topographical and archaeological features. Mud maps are extremely useful, but a survey will provide the location of site features in relation to known survey points—which are needed for an accurate site plan (Bowens 2009:117). Control points need to be established on the site. These form known points and are given arbitrary coordinates so they can be plotted to scale on a site plan. Perhaps the easiest method of establishing control points is to set up a baseline (Bowens 2009:118). Unknown points (site features) can then be plotted in relation to the control points. A baseline should be straight, extend past the ends of the site, and be positioned to one side or through the middle of the site itself (Tuttle 2011:126). Once a baseline has been established the next step is to start recording the location of site features. When recording site features, archaeologists take offset measurements at right angles (or 90 degrees) from the baseline (Bowens 2009:120; Burke and Smith 2004:97; Feulner and Arnold 2005:288; Tuttle 2011:126). Two archaeologists are required for the baseline offset technique; one holds the terminal (or ‘dummy’) end of the tape to the feature while the other records measurements on the baseline. The baseline offset technique is relatively quick to set up and does not require very much equipment, so it is frequently used to record the location of site features. It is primarily used to acquire horizontal measurements, but can also be used to record vertical profiles as well. The accuracy of this method is largely dependent on the archaeologist’s ability to ensure his/her measurements are recorded 90 degrees to the baseline.  The smallest measurement observed when swinging the offset tape in an arc over the baseline denotes when the tape is at a right angle relative to it (Figure 2) (Burke and Smith 2004: 98).

baseline offset

Figure 2. Establishing a right angle on a baseline (Bowens 2009:121).

Trilateration is another low tech method similar to the baseline offset technique, and can also be used to record site features. Measurements are taken from two control points along the baseline to the feature that is being recorded (Figure 3); this works best if the angle between the two tapes is between 30 and 120 degrees (Bowens 2009:121). This method can use more than two points for measurements. In fact, two points are the minimum; if three or more points are used the results are more accurate (Feulner and Arnold 2055:290). On some sites a single or straight baseline may not be possible. In this case, a network of control or datum points can be established (Tuttle 2011:126). These control points can be assigned arbitrary coordinates (just like the baseline control points) so that they can be used to accurately plot features on the site plan. Trilateration does not require a baseline, but rather known control points. Consequently, if a datum network is employed on the site in question, this technique could be used.

trilateraltionb

Figure 3. Measuring features through trilateration (Bowens 2009:122).

Baseline offset and trilateration surveys are two of the easiest methods available for recording a site. Both processes can be carried out with limited equipment by a couple of archaeologists. Each method records the site in two dimensions, but there are other forms of survey that record sites in three dimensions. Computer programs make creation of three dimensional plans much easier. The Direct Survey Method (DSM) uses distance and depth measurements to plot site features, and is similar to trilateration. Distances are measured from control points, as are site depths. The DSM computer program takes into account differences in depth and generates a digital site plan (Bowens 2009:127).

A site plan is not the only outcome that is created during a pre-disturbance survey. Site details, such environment, water depth, and visibility are collected. Photographs that detail site features are an essential outcome, and biological surveys—while not standard—are also beneficial. The aim of a pre-disturbance survey is to accurately record the site as it currently exists, and collect as much information as possible to facilitate future research.

A site plan is not the only information that is recorded during a pre-disturbance survey details such about the site environment such as water depth and visibility as mentioned above should be collected, photographs of a site are essential and a biological survey would also be beneficial. The aim being to accurately the record the site as it currently exists collecting as much information as possible to make future work on the site easier.

References

Bowens, A. (editor)

2009       Underwater Archaeology: The NAS guide to Principles and Practice, Second Edition. Wiley-Blackwell, London.

Burke, H. and C. Smith

2004       The Archaeologist’s Field Handbook. Allen and Unwin, NSW.

Feulner, M. A. and J. Barto Arnold III

2005       Maritime Archaeology. In Handbook of Archaeological Methods, edited by H. D. G. Maschner and C. Chippindale, pp. 270-305. vol. 1. AltaMira, USA.

Flinders University

2013       Methods in Underwater Archaeology Training. Faculty of Education, Humanities and Law. Electronic document, http://www.flinders.edu.au/ehl/archaeology/research-profile/current-projects/abpp/methods-in-underwater-archaeology-training.cfm, accessed 20 September 2013.

Green, J.

2004       Maritime Archaeology: A Technical Handbook, Second Edition. Elsevier Academic Press, USA.

Tuttle, M. C.

2011       Search and documentation of underwater archaeological sites. In The Oxford Handbook of Maritime Archaeology, edited by A. Catsambis, B. Ford and D. L. Hamilton, pp. 114-132. Oxford University Press, New York.

Trash to Treasure: Methods of Preserving Maritime Archaeological Artefacts.

Artefacts associated with submerged sites experience vastly different environmental and chemical effects than their terrestrial counterparts. Submerged sites often contain artefacts that terrestrial sites rarely exhibit, making the protection of these artefacts for future generations vital. Maritime archaeologists often have different approaches and methods of conserving previously submerged artefacts. For example, artefacts or materials that have been located in a sodium chloride solution (salt water) for extended periods are often well preserved but also friable in nature while artefacts recovered from anaerobic marine environments are also in better condition than those recovered from aerobic environments.

In the vast majority of cases, artefacts and materials that have survived have done so by reaching a chemical and physical equilibrium with their environment. If researchers do not conserve these artefacts properly and in a timely manner after their recovery, they are likely to deteriorate at an extremely rapid rate (Hamilton, 1997:4). Artefacts that are allowed to dry without conservation treatment produce sodium chloride crystals, which, in some cases, cause the artefacts to break and splinter, thereby destroying them. It is also important to note that organic and inorganic materials react differently to salt water (Hamilton, 1997:4). This blog will identify and outline some basic conservation techniques used to conserve both organic and inorganic artefacts, focusing primarily on chemical conservation.

Wood

Successful conservation of wood depends upon knowledge of wood structures and types. Two broad categories exist: hardwood and softwood. Defining these types of wood is beyond the scope of this blog, but oaks and birch are examples of hardwoods, while pine is a typical species of softwood. Wooden artefacts located on submerged sites for long periods lose much of their cellulosic components, making them more permeable (Hamilton 1997:32). This loss of structural cellulose means that while the wood is water logged, it will maintain its shape. However, if the artefact is exposed to air, and the water within evaporates, the surface tension holding it together will break, causing considerable structural shrinkage and distortion (Hamilton 1997:33). Two methods of conserving waterlogged wood are discussed below.

Polyethylene Glycol (PEG) Method

This was the first reliable method of treating waterlogged wood and is simple to carry out (Hamilton 1997:33). PEG variants have similar physical properties to wax but are different in that they are freely soluble in alcohol and water. This method is only appropriate for small objects. PEG is also corrosive to metals (primarily iron), so it is necessary to ensure that the conserved wood is not in close proximity to metal after conservation (Hamilton 1997:35).Figure 1

Figure 1. The various stages of the PEG conservation process (Image created by author)

Figure 2

Figure2.  The third stage of the PEG conservation method. The first beaker is the wood in the PEG solution. The second beaker identifies the increase in solution temperature as well as the percentage of PEG penetration of the wood. The third beaker, at 60°C, shows full penetration of the PEG solution in the wood (Image created by author)

Acetone-Rosin Method

This method is one of the more expensive ways to treat wood, and involves replacing the water in wood with natural rosin (usually pine) called colophony.  Acetone-Rosin conserves hardwoods that PEG method cannot penetrate (McKerrell, Roger and Varsanyi 1972). It is generally considered the wood treatment of choice as the finished product is light, dry, strong, can be easily glued and repaired, and does not negatively react with metals (McKerrell, Roger and Varsanyi 1972).

Figure 3

Figure 3. Recommended procedure for the Acetone-Rosin method of wood conservation (Image created by author)

Bone, Ivory, Teeth, and Antler

Bone, ivory, teeth and antler are comparable in that they are made of an inorganic lattice composed of calcium phosphate, carbonates and fluorides, and an organic ossein. However, their precise compositional percentages differ significantly depending on several factors, including utility, species, and geographical location (Lafontanine and Wood 1982). Bone, ivory, teeth and antler are warped by heat and moisture and decompose when exposed to water. Ossein is decomposed by hydrolysis and acids disintegrate its inorganic framework (Hamilton 1997:22). When waterlogged, these artefacts can be reduced to a sponge-like material while in arid environments become dry, brittle, and fragmented.

figure 4

Figure 4. The inorganic lattice of bone and ivory, and organic ossein that forms the collagen of bone (Smithsonian  Institution 2013)

In order to remove soluble salts from bone, ivory, teeth and antler, rinse these objects in successive baths of water (a percentage fresh and a percentage salt) until the mixture is 100% fresh. Upon completion of this phase, begin the process anew using fresh and distilled water (Lafontanine and Wood 1982; Hamilton 1997:22-4). The following image identifies further steps in conservation.

Figure 4

Figure 5. Stages of bone, ivory, teeth and antler conservation. (Image created by author)

Leather

Before conservation, it is necessary to remove all soluble salts; this procedure is the same as the one used for bone, ivory, teeth and antler (Hamilton 1997:43). Conservation methods for leather include the PEG method (described above) as well as freeze-drying. The freeze-drying technique follows the PEG method but includes the use of a fungicide in the PEG solution, after which the artefact is immersed in acetone and frozen carbon dioxide (CO2). The artefact is then placed in a freeze drying chamber for 2-4 weeks (Hamilton 1997:47).

Glass

Glass consists of 70-74% silica, 16-22% potash or soda ash and 5-10% flux (lime) (Hamilton 1997:29; Brill 1962). The sodium (Na) and potassium (K) carbonates in the glass can leach out, especially in salt water, which leaves only a porous silica (SiO2) network. This typically creates a frosty appearance. Alternatively, decomposed glass appears laminated with iridescent layers. Conservators have different opinions about how to effectively treat glass, and have proposed methods ranging from storing or exhibiting the glass in low humidity to applying resins to seal it. Newton and Davison (1989), and Plenderleith and Werner (1971) discuss various methods of conservation for glass. The latter (Plenderleith and Werner 1971:345) present a treatment of unstable glass shown below (Figure 8).Figure 6

 

Figure 6.  Treatment of unstable glass presented by Plenderleith and Werner in their 1971 publication The conservation of antiquities and works or art: treatment, repair and restoration (Image created by author)

Metals

Metals are usually defined as cathodic (noble) or anodic (less noble). A complete overview of conservation methods for each type of metal is beyond the scope of this blog; consequently, only anodic metal iron will be reviewed.

Figure 7

Figure 7. Galvanic Corrosion Chart ranging from gold (a cathodic metal, which is more protected) to zinc (an anodic, which is less protected and more subject to corrosion) (Image created by author)

Iron usually presents the most puzzling issues with conservators due to the variety of conditions and environments in which iron corrodes. Iron corrodes five times faster in salt water than it does in soil, and ten times faster than in air, and this corrosion is normally electrochemical (Hamilton 1997:54-60). The process of conservation is determined by a preliminary evaluation of the condition of the object. Treatments for iron include electrochemical cleaning (including galvanic cleaning and electrolytic reduction), alkaline sulphite, and chemical cleaning including tannic acid, annealing, and water diffusion in alkaline solutions (Argo 1981).

Alkaline Sulphite Treatment

This treatment can be used on both cast and wrought iron, and is most effective on artefacts that are moderately or highly corroded; however, the iron object must have a metallic core or treatment will be unsuccessful (Bryce 1979:21).

Figure 8

Figure 8. The stages of Alkaline Sulphite Treatment (Image created by author)

Conserving artefacts recovered from submerged sites is a lenghtly and sometimes costly process. It is, however, a very important aspect of archaeological investigation. Each artefact, depending on its chemical composition and level of decomposition, has numerous methods of conservation. The aforementioned methods and techniques are by no means an extensive or  complete list of every method used for every artefact; they merely act as a starting point for those looking to conserve items from the archaeological record.

References

Argo, J.

1981 On the Nature of ‘Ferrous’ Corrosion Products of Marine Iron. Studies in Conservation, 26(1):42-44.

Brill, R.H.

1962 A Note of the Scientist’s Definition of Glass. Journal of Glass Studies, 4:127-138.

Bryce, T.

1979 Alkaline Sulphite Treatment of Iron at the National Museum of Antiquities of Scotland. The Conservation and Restoration of Metals.  Scottish Society for the Conservation & Restoration of Metals, Proceedings of the Edinburgh Symposium 1979: 20-23.

Hamilton, D.L.

1997 Basic Methods of Conserving Underwater Archaeological Material Culture. U.S. Department of Defence, Washington.

Lafontaine, R.H. And P.A. Wood

1982 The Stabilization of Ivory Against Relative Humidity Fluctuations. Studies in Conservation, 27(3):109-117.

McKerrell, H., Roger, E., and A. Varsanyi

1972 The Acetone/Rosin Method for the Conservation of Waterlogged Wood. Studies in Conservation, 17:111-125.

Newton, R.G. and S. Davison

1989 The Conservation of Glass. Butterworth-Heinemann Limited, London.

Plenderleith, H.J. and A. E.A. Werner

1971 The Conservation of Antiquities and Works of Art: Treatment, Repair, and Restoration. Oxford University Press, London.

Smithsonian Institution

2013 An Inside Look at Bone. Electronic document, http://anthropology.si.edu/writteninbone/inside_look.html, accessed  September 7, 2013.

Further Readings

Angelucci, S., Florentino, P., Kosinkova, J., and M. Marabelli

1978 Pitting Corrosion in Copper and Copper Alloys: Comparative Treatments Tests. Studies in Conservation 24:147-156.

Dowman, E.A.

1970 Conservation in Field Archaeology. Methuen and Co., London.

Koob, S.P.

1986 The use of Paraloid B-72 as an Adhesive: Its Application for Archaeological Ceramics and Other Materials. Studies in Conservation, 31:7-14.

Kotlik, P., Justa, P., and J. Zelinger

1983 The Application of Epoxy Resins for the Consolidation of Porous Stone. Studies in Conservation, 28:75-79.

Wanhill, R.

2013 Stress Corrosion Cracking in Ancient Silver. Studies in Conservation, 58(1): 41-49.

Watson, J.

1987 The Application of Freeze-Drying on British Hardwoods from Archaeological Excavations. In Gratten, D.W. (ed), Proceedings of the ICOM Waterlogged Wood Working Group Conference, pp 237-242. ICOM, Committee for Conservation, Waterlogged Wood Working Group, Ottawa.