Preservation

Sustainable Archaeology McMaster: a day in the life of an archaeological repository

The field season is over, the excavation is complete, the artifacts have been analyzed and the report has been all nicely written up. Now what? What are you supposed to do with all the stuff? This is a problem that has just about come to its breaking point in Ontario. Here, legislation dictates that the licensed archaeologist responsible for collecting the artifacts is also responsible for keeping the artifacts. Forever.

This in itself is no bad thing – it ensures that collections are not simply discarded after excavation, in theory preserving them for the benefit of future generations. However, there are no rules or systems in place for ensuring that these collections are kept in appropriate storage conditions along with all of the accompanying information necessary for understanding what the artifacts are and where they came from. Unfortunately, it takes money, time, and training to ensure that a collection is properly cared for and made accessible to the public. As a result, due to the significant financial burden that securing decent storage space often requires, many collections are kept in poor conditions, are separated from their provenience information, and are completely inaccessible to the public and researchers.

Sustainable Archaeology is an initiative aimed at responding to this issue. With two locations (one at the University of Western Ontario and one at McMaster University), Sustainable Archaeology is an archaeological repository and research facility which specializes in the storage, preservation, and accessibility of Ontario’s archaeological collections. Here at the McMaster facility we have both a dry and wet lab available for use by researchers in addition to our collection storage space. Unlike many archaeologists, our “raison d’etre” is not to conduct our own research, but rather to make it possible for others to do so.

Movable shelving allows for more compact storage meaning that we can really make the most of our space. All artifacts are stored in the archival quality green boxes visible here and are labelled using an RFID tagging system to track their location.

Movable shelving allows for more compact storage meaning that we can really make the most of our space. All artifacts are stored in the archival quality green boxes visible here and are labelled using an RFID tagging system to track their location.

Sustainable Archaeology McMaster's polarizing microscope

Sustainable Archaeology McMaster’s polarizing microscope

The wet lab portion of the SA McMaster facility is where the production of thin sections takes place. This area can also be used to clean artifacts.

The wet lab portion of the SA McMaster facility is where the production of thin sections takes place. This area can also be used to clean artifacts.

These sinks and drying racks can be used to clean and dry artifacts

These sinks and drying racks can be used to clean and dry artifacts

The dry lab portion of our facility is used to work with any materials which could be harmed through exposure to moisture. This is where we do all our cataloguing and preventive conservation work.

The dry lab portion of our facility is used to work with any materials which could be harmed through exposure to moisture. This is where we do all our cataloguing and preventive conservation work.

Most of our time is spent ensuring that collections are kept in good condition, and that material can be easily found and accessed within the collection. Typically this involves researching the background of the collections in our care, assessing their condition, and repackaging them when necessary. Many of the collections we’re currently working with were excavated in the early- to mid-twentieth century, and have been separated from their contextual information over time. This means that sometimes we open a box to find a bunch of mysteriously labelled artifact bags without any clues as to where they came from or what the labels mean. This is where the detective work begins, as we use whatever information we do have left to track down the rest of the collection’s context. Sometimes we are lucky and the archaeologist will have published a paper or left us a catalogue which clarifies everything — then again, sometimes we’re unlucky and those hopeful looking blank fields in our collection catalogue must remain empty for the time being.

Collections Management Assistant, Emily Meikle working on a stemmed projectile point found at the Sealey Site near Brantford, Ontario

Collections Management Assistant, Emily Meikle working on a stemmed projectile point found at the Sealey Site near Brantford, Ontario

Each archaeologist has their own way of packaging artifacts. In this unique example dating from 1937-1940, a cardboard ammunition box was used to package a number of small potsherds.

Each archaeologist has their own way of packaging artifacts. In this unique example dating from 1937-1940, a cardboard ammunition box was used to package a number of small potsherds.

While the this site did need to be repackaged in acid free polypropylene bags, it was conveniently well labeled, including an individual label for each artifact

While the this site did need to be repackaged in acid free polypropylene bags, it was conveniently well labeled, including an individual label for each artifact

Just as packaging standards vary, so do labeling methods. Shown here are a number of potsherds all from the same site, but labeled using a number of different systems. Some of them aren't labeled at all.

Just as packaging standards vary, so do labeling methods. Shown here are a number of potsherds all from the same site, but labeled using a number of different systems. Some of them aren’t labeled at all.

Often beads are strung on wire susceptible to corrosion and must be removed and restrung using acid free thread. This process is also a good opportunity to inspect glass beads for glass disease -- a degradation which affects unstable glass and can spread between artifacts through contact.

Often beads are strung on wire susceptible to corrosion and must be removed and restrung using acid free thread. This process is also a good opportunity to inspect glass beads for glass disease — a degradation which affects unstable glass and can spread between artifacts through contact.

Frank Wood was an active collector of archaeological material in the early part of the 20th century. Much of the material in our care was included at one point in Wood's personal collection. As a result, his catalogue of artifacts is often a valuable resource in recovering the context of orphaned artifacts. As pictured above, we keep a photocopied version of the original in the lab for ready use.

Frank Wood was an active collector of archaeological material in the early part of the 20th century. Much of the material in our care was included at one point in Wood’s personal collection. As a result, his catalogue of artifacts is often a valuable resource in recovering the context of orphaned artifacts. As pictured above, we keep a photocopied version of the original in the lab for ready use.

Complementing our collections work, lab technician Samantha Atkins is also hard at work pioneering a thin sectioning protocol for use with our polarizing microscope. Slicing archaeological material (such as stone, ceramic, and teeth) into thin sections and viewing them under the polarizing microscope, it is often possible to determine from where a natural material was sourced, or the season during which an animal was killed. This information can be extremely valuable to an archaeologist, and as such Sustainable Archaeology has put an emphasis on creating thin sectioning protocols that can help provide archaeologists with as much information as possible. In order to do all of this, Sam’s days typically consist of a mix of research and experimentation. Because archaeological studies using thin sectioning rarely describe the process of creating thin sections, Sam has had to draw upon other fields (such as geology) to inform her techniques, and is also beginning to assemble a network of archaeological thin sectioning experts. In between bouts of research and experimentation, Sam is also responsible for photographing artifacts and editing images to be featured in our digital resources.

Lab Technician, Samantha Atkins working away at her deer teeth thin sections

Lab Technician, Samantha Atkins working away at her deer teeth thin sections

Samples to be thin sectioned are first impregnated with an epoxy formula.

Samples to be thin sectioned are first impregnated with an epoxy formula.

Thin section samples are taken only from material that does not have any accompanying contextual information. Once the epoxy pucks have solidified, the samples will be cut into slices and ground and polished down to the necessary thickness of 30 microns.

Thin section samples are taken only from material that does not have any accompanying contextual information. Once the epoxy pucks have solidified, the samples will be cut into slices and ground and polished down to the necessary thickness of 30 microns.

Thin sectioning test samples in various states of progression

Thin sectioning test samples in various states of progression

These mandibles from a recently deceased white-tailed deer were de-fleshed and sectioned in order to produce a tooth thin section with a positively dated season of death. Good archaeology doesn't always smell nice.

These mandibles from a recently deceased white-tailed deer were de-fleshed and sectioned in order to produce a tooth thin section with a positively dated season of death. Good archaeology doesn’t always smell nice.

To learn even more about what we do or to explore our collection online, check out our website or follow us on Twitter or Facebook.

Filming Archaeologists

I tell people I have the very best job. I get to work with a great group of archaeologists at the Illinois State Archaeological Survey–Prairie Research Institute at the University of Illinois. I have filmed a mummy getting a CT scan, to a lost fort in Warsaw, Illinois, to the most recent story of the bob kitten that was buried like a human. Our archaeologists and staff make my job very easy and let me come to their sites, sit through interviews, and help me tell the story of the archaeological and preservation work they are doing.

 

 

A Day in an Archaeological Conservation Program

I’m a Conservation Specialist for the UCLA/Getty Conservation Program, a graduate conservation training program specializing in the conservation of archaeological and ethnographic materials.  In our 3 year course, we train students in the methods and techniques used for the examination and preservation of objects and have them understand the properties of materials, how they deteriorate and ways to slow down or prevent further deterioration.

In a typical day our students attend lectures in the morning on various aspects of conservation and then follow that in the afternoon with work in the lab.  We just had an intake of a new class in the Fall of 2011 and they spent their first year learning about and working on materials such as archaeological ceramics, glass, metals, and  textiles.

In one course they learned about the deterioration of archaeological ceramics and the damage caused by soluble salts. Students then determined how to identify the salts and remove them. Here a student is taking a conductivity reading of wash water as she desalinates a small ceramic vessel.

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Archaeological Conservation in Northern Highland Ecuador

I spent this summer working as a conservator for the Pambamarca Archaeological Project (PAP), located in northern highland Ecuador, near the town of Cangahua.  As the conservator on the project, my job was to examine and conserve the finds excavated to ensure their long term preservation and to aid in archaeological research.  Most of the work taking place here is focusing on sites and fortresses located on various hilltops in the region.  The research hopes to understand the indigenous cultures known as the Cayambes, that lived here before the Inca conquered this area in the 1500’s, and also to look at the interactions between the groups after that conquest.

Most of my work is based in the lab and focuses on processing the finds that come in each day.  This can be something as simple as washing some sherds to something more complicated like reconstructing an entire ceramic vessel.  I also sometimes work on site helping archaeologists excavate and lift fragile artifacts.  This is my second year working on the project and here are some of the things I do during a typical work day:

Area where we work

 

The site of Quitoloma, one of the hilltop fortresses excavated by PAP.

 

Finds that come in, such as pottery sherds in bulk, need to be washed daily.

 

When enough of a ceramic vessel is preserved, we reconstruct it. Here I am starting to reconstruct the neck and rim of an aribalo, a vessel form used to hold liquids.

 

This a painted aribalo that was reconstructed. The rim and neck are missing.

 

Because of the missing upper section of the vessel, some of the joins are not well supported. This fragment only attaches on one side and needs extra support. Conservators sometimes do something called “gap-filling” to fill missing areas to keep certain fragments in place. The red arrow points to an area where a fill was placed (made up of a mixture of a resin known as Paraloid B-72 mixed with a material called glass microballoons to make it thicker) to fill the gap below the sherd to support it.

 

Sometimes conservators are called to the site to help archaeologists excavate and lift fragile material. Here I am preparing to lift a fragment of a burnt reed mat.

 

Here is a section of the burnt mat in situ. It was found on the floor of an Incan store room with a thick layer of burnt corn on top. Organic materials don’t often preserve well, but luckily this mat was burnt allowing it to survive this long in the soil.

 

The mat was very fragile and in a lot of pieces so it could not easily be excavated and lifted.  I needed to do something called block lifting where you excavate around the object and then lift it out in a block of soil. Here is the mat after a facing of Japanese tissue and a reversible resin are applied on the exposed surface. This helps to hold all the fragile fragments together during lifting.

 

Once lifted and back in the lab, the mat could be carefully excavated from the soil and consolidated with a dilute resin when needed to strengthen it.

 

Here is the mat after treatment. It can now be examined and studied to identify the materials and methods used in its construction.

 

Not all of our work is just treating artifacts. Conservators spend a lot of time documenting and recording the treatments they undertake on artifacts. Here a student helps to enter data about artifacts excavated into the project database.

 

We also spent time labeling the artifacts in the lab. We used a barrier coat of Paraloid B-72 applied to a discrete area of the artifact to write the catalog number on using an archival ink pen. This would allow the artifact to be linked to its catalog number, and the archaeological information in the database, in case it ever got disassociated from the label in the bag it was packed in.

 

Since the excavation is run as a field school, it means that students are on the project as part of a course to learn about archaeolgy and archaeological field methods. This gives me an opportunity to teach students about conservation and have them help me in the lab if they are interested. Here a student helps me find joins for a vessel I was reconstructing.

 

So as you can see, archaeological conservators are kept really busy on excavations doing a wide range of activities.  If you are interested in learning more about conservation and what conservators do, or think you might be interested in pursuing studies in conservation, you can check out the website for the American Institute for Conservation or the International Institute for Conservation for more information.