Tuesday, July 12, 2011

Site Conservation at Gordion

Gordion site conservators at work. Photo by Andrea Berlin.

An average visit to Gordion will include three stops: the museum, the Midas Tumulus, and the site located on the mound. For the last few seasons, Frank Matero and his students at the University of Pennsylvania programs in Architecture and Historic Preservation have been diligently working on preserving the site.

This season, site conservation projects include the installation of viewing pavilions, documentation, soft capping, and stabilizing the stone walls of the site. Objects conservation intern Lily Doan was able to join the site conservators for a day of injection grouting.

Here are some highlights from this season's site conservation projects:

The viewing pavilions, constructed from locally purchased
metal pipes and fabric, provide much needed shade for
visitors to the site.

UPenn students document the site. Photo by Andrea Berlin.

Locally produced mud bricks drying in the hot Turkish sun.
These bricks are a component of soft capping, a system where
the introduction of moisture, which may cause damage to the
stone walls, is regulated with plants installed on top of the wall.

Site conservator Alex Lim sifting lime in preparation
for grouting. Photo by Andrea Berlin.

Meredith Keller, site conservator, mixing the grout.

Objects conservator Lily Doan uses an air compressor to 
clean cracks in preparation for grouting.

Wednesday, July 6, 2011

Tomb Monkeys

The entrance into the Midas Tumulus
In addition to working on the artifacts in the Gordion Museum and in storage we also do some work in the fabulous wooden tomb chamber inside the Midas Tumulus. The Midas Tumulus is one of the archaeological resources open to the public in and around the village of Yassıhöyük.  Located across from the Gordion Museum it gets up to 60,000 visitors every year.

This year there are been a project to view features on pitched roof of the tomb and we have been working with the archaeologists who are carrying out the project to document the activity.

Documenting work on the roof of the 2700 year old tomb
Working on and around the tomb chamber involves some rather acrobatic maneuvers. Also being inside a fence and at times viewed by visitors gives a rather interesting flavor to the work- thus the term "tomb monkeys" has developed to describe the archaeologists working in the tomb day after day.

Silverback tomb monkey imparting advice to his assistant
We are also continuing environmental monitoring of the tomb to ensure that visitation, archaeological documentation activities and any unknown problems don’t create an environment that would endanger the wooden structure. This project, on-going for over a decade, has shown that there are small changes in temperature and environment that track what’s going on outside. The changes are slight and the ancient wooden structure (so far) is not in any danger from theseagents of deterioration.

Looking at 2010-2011 datalogger data
Tomb monkeys headed home after a long day 

Monday, July 4, 2011

Road Trip to Hittite Sites

From left to right:
Cybele Tom (NYU Conservation Program, Sardis Conservation Intern)
Jessica Pace (NYU Conservation Program, Sardis Conservation Intern)
Alex Lim (Research Fellow, UPenn Architectural Conservation Laboratory)
Lucas Stephens (Doctoral Student, UPenn AAMW Program)

The "weekend" at Gordion, which is from Wednesday afternoon until Thursday, is a good time to venture beyond the dig house and explore other areas of Turkey. Last weekend, Cybele Tom and Jessica Pace, conservation interns at Sardis, an archaeological site in Southwest Turkey, joined Gordion team members on a visit to several Hittite sites located in Central Anatolia.

Yielding to a flock of geese on our way to Hattusa.

The trip began with a tour of the Gordion site, tomb, and museum, as well as Dua Tepe. After lunch at the Gordion dig house, we set out on a road trip to the city of Bogazkale, where we stayed at a charming hotel and enjoyed a lovely dinner in a restaurant with Ottoman style furnishings and a stone fireplace.

The Hittite sites and museums we visited include Hattusa, Yazilikaya, and Alacahoyuk. This group of students and recent graduates included three objects conservators, an architectural conservator, and an archaeologist, which made for very interesting, and interdisciplinary, conversation regarding the sites and museums.

Here are a few highlights from our trip:

Dua Tepe. A memorial dedicated to the Turkish War of Independence.
Reconstruction of mudbrick walls of Hattusa, capital of the Hittite Empire.
The amazing landscape that surrounds Hattusa.
The reliefs of Yazilikaya, a sacred site of the Hittites.

The gates of Alacahoyuk, a Hittite settlement.

Our adventure ended in Ankara, where the two groups separated and returned to their respective sites. We would like to thank our friends from Sardis for joining us on a wonderful trip!

Friday, July 1, 2011

Saf Su (Pure or Distilled Water) at Gordion

Our goal: obtaining saf su.

Distilled or deionized water is important in many treatments completed here at Gordion Excavations. Therefore, one of our first and top priorities is obtaining an appropriate source of water, which proved to be quite a challenge this season. We first attempted the deionizing columns left over from previous years, but after several rounds the conductivity of the resulting water was off the charts.

Discussing the deionizing column with a chemical salesman in Ankara.

During a trip to Ankara, we ventured on a mission to find a local source for purchasing deionizing columns. The set up for purchasing chemicals and supplies in Ankara is rather amusing. In one section of town, there are a few strip malls with stores that sell medical, laboratory, and chemical supplies. In many ways, the experience feels like purchasing a car. The chemical salespeople contemplated the column: they tapped it, shook it, sniffed it, then called in reinforcement, who also tapped it, shook it, and sniffed it. After several visits to different stores, many confused looks, and a few phone calls, we were unsuccessful in locating a column.

Angie sets up the still outside of the lab.

Defeated in our quest for a deionizing column, we set up the still back at the lab. Although the process is slow, after several days of running the still, we were able to obtain enough distilled water for the season. In case we run out, several small bottles of distilled water were purchased from a petrol station in Polatli, a nearby town.

Feeling sorry for the water-deprived objects conservators, Gordion
archaeologists purchased these cute little bottles of distilled water.

Perhaps next season will be more successful in the quest for purchasing a deionizing column in Turkey - a tip from an Ankara local suggested home improvement stores that may carry water filtration systems designed for the home.

With saf su in hand, Gordion objects conservators commenced with desalination and other treatments involving water.

Sunday, June 26, 2011

Soccer and Mulberries in Yassihoyuk

The Yassihoyuk mosque.

One afternoon, during our walk to the museum, we passed by the Yassihoyuk mosque. The courtyard of the mosque was filled with children from the village. We stopped to say hello and practice our Turkish. I do believe one boy said "Your Turkish is bad." Children are so honest.

Soccer in the mosque courtyard.

Angie joins the soccer game.

The children began a game of soccer, and we decided to sit in the shade of the courtyard and observe. Angie couldn't resist joining the game. A couple of the kids were standing on the wall, picking some fruit off a nearby tree. We stopped to get a closer look, and saw some white mulberries ripe for the picking! While we tried to figure out which berries were best to eat, an older village woman came out help us. The next 15 minutes were spent eating handfuls of delicious, juicy mulberries she picked for us. What a wonderful afternoon break, before heading back to work at the lab!

Delicious mulberries.

Saturday, June 25, 2011

Slumping Ceramics

Gordion archaeologists are not excavating this season which means that we can devote more of our time to taking care of the collection. Our job as conservators does not end once objects are cleaned and stabilized after they are excavated. A continuing challenge is our slumping ceramics. Most of our pots, plates, and other ceramic vessels were carefully assembled from many fragments because they rarely come out of the ground unbroken. In the earlier days of Gordion, a PVA resin adhesive was used to glue the ceramics back together. Over time, these earlier ceramics have started to sag, slump, and come apart.

This Phrygian jug, treated in 2009, slumped over the course of one year
and could no longer stand on its own.

The adhesive slowly starts to soften and the joins begin to pull apart exposing strings of adhesive. One reason this happens is that the adhesive's glass transition temperature, or Tg, is too low. The Tg refers to the temperature where a material like an adhesive goes from a hard, brittle material to a much softer, rubber-like material. Our storage areas have no air conditioning and the temperatures can get pretty hot! The older adhesive used here has a Tg that is in the same range as the high temperatures in storage so the adhesive starts to soften and pull apart. 

Adhesive strings in joins indicate that the vessel is unstable
and could begin to slump and fall apart. 

We keep an eye on our ceramics each year to determine if there are any emergency cases that should be treated. The only solution is to remove all of the adhesive and put them back together again with an adhesive that has a higher glass transition temperature. 

A collapsed pot that is being treated this year. 

Friday, June 24, 2011

An Update on Salts

Here are some microscopic images of salts present on a ceramic from a previous post.

Microscopic image of hair-like crystals on the blue-colored fills.

The ceramic surface shows granular salt crystals.

We are currently in the process of preparing the ceramic for desalination, including consolidation of flaking surfaces and removal of old plaster fills. But before we desalinate, we have to find a good water source, which is a challenge out in the field. Stay tuned for our adventures hunting down an appropriate water source!

Tuesday, June 21, 2011

Unseasonal Rain and Its Effects on Cleaning Stone Altars

The normal field season at Gordion experiences very warm weather. However, this summer so far has been unusually cold and wet; in fact, it rained nearly every day for a week!

We enjoy the amazing cloud formations on a walk back to the dig house.
Muddy roads after a sudden downpour of rain.

Although the rain allows for enjoyment of beautiful clouds like the ones seen above, our walks to the site museum were rather muddy. Cars must also contend with the downpour of rain; the architectural conservation team was stranded on site when their vehicle got stuck in the mud. Kenneth Sams, Director of Gordion Excavations, had so much mud stuck in his tires, they caught on fire while he was driving!

However, there are some surprising benefits to the rain. In previous seasons, the deposits on two stone altars were particularly hard and difficult to remove. The elevated humidity from the recent rains has softened the deposits, and some areas are now flaking off rather easily. We plan to take advantage of the situation and remove the deposits while they are still soft from the rains. More stubborn areas will first be softened with a poultice and gently removed with a scalpel or chisel. This is a particularly useful approach for deposit layers closest to the stone.

A poultice, comprised of paper towels soaked in water, was applied to soften the deposits.

Last season, the conservation team applied a toilet paper squeeze to study the defaced inscriptions. Unfortunately, the inscription was still not legible, perhaps due to fine layers of dirt. Hopefully, after further cleaning, we will have more luck this season!

Monday, June 20, 2011

Visiting the Gordion Frescos

Our conservation season got off to a great start this week with a trip to the Museum of Anatolian Civilizations. This museum, housed in an historic bazaar building in Ankara, contains some of the best finds from the area's excavations including our own Gordion wooden furniture. Research still continues behind the scenes at the museum. Dr. Susanne Berndt-Ersöz has been researching and reassembling the Gordion fresco fragments excavated in the 1950s. These frescos were discovered in a small, partly subterranean building known as the Painted House and have been dated to 500-490 BCE. 

Reassembled fragments
1957 watercolor reconstruction by Piet de Jong

Most of the fragments are currently housed in small, acidic paper boxes. These boxes are harmful to the fragments and do not allow the reassembled pieces to be stored together. Elizabeth Drolet, one of our 2010 interns, worked on a rehousing plan over the past year. We went to evaluate the fresco's condition and discuss the plan with Dr. Berndt-Ersöz. We were excited to see these much talked about frescos in person!

Latif Özen, our friend and colleague at the museum, also took us on a tour to see the museum's conservation laboratory. There are a dozen or more conservators that work in the laboratory and almost half of the them of scientists. Latif, a chemical engineer, has been analyzing the fresco pigments using their new portable x-ray fluorescence spectrometer. This instrument is non-destructive and can determine what elements are present without taking a sample. We hope to hear more about the analysis in the near future and will keep you posted!

Latif and Lily in the museum's conservation laboratory

2011 Condition Survey: Salts

We start the season at Gordion with a condition survey of the museum collection. A survey is an overview of the collection, where we quickly examine each object on display and note condition issues. The survey is completed on a yearly basis, allowing for comparison of survey results with previous years so that objects in need of attention can be prioritized.

One of the condition issues we have encountered is the presence of salts, a common problem with some archaeological materials, particularly ceramics. When hearing a conservator talk about salts, the white crystalline material found in the common kitchen, possibly occupying a shaker marked with an "S" on your dining room table, might come to mind. Actually, this is not too far off the mark, because table salt, aka sodium chloride, is simply a purified form of one type of salt.

It may sound odd that salts are present in archaeological objects, but it is a fairly common occurrence, since salts are present in burial dirt. If they are not removed, then salts may either obscure the surface or cause damage to an object.

During our survey, we discovered salts present on this ceramic:

The salts are the powdery white crystals seen here on the rim.
The salts have caused some damage to the surface.

A particularly interesting, and unusual, discovery is the blue area in the above green box, which is located in a fill rather than the original ceramic. Examination of this strange blue area revealed hair-like salt crystals that are not found on the other, non-blue fill material, and is different in shape from the other salt crystals present on the ceramic.

The blue area of the fill contains hair-like crystals that are
different from other salt crystals found on the ceramic.

The objects conservation team plans on treating this ceramic to remove the salts, via a process called desalination. Samples of this strange blue material may be removed for analysis back in the US, at one of the conservator's home laboratories. The analysis may shed light on why and how these crystals were formed on the fill material. Stay tuned for an update on this treatment!

Sunday, June 12, 2011

We're back: The 2011 Conservation Season Begins!

The Gordion Objects Conservation Program is gearing up for another season as the conservation team begins arriving this week. Our season began June 11 and will go through July 13. Conservators Angie Elliott and Jessie Johnson will switch off in the middle of the season and graduate student Lily Doan ('12) from the UCLA/Getty Program in Archaeological and Ethnographic Conservation will be around the entire season. Angie has begun to set up the conservation lab at the Gordion Museum so we will soon have more to tell you about our season's projects. In the meantime...

Our first challenge has been the thickest vegetation that we've ever seen at the site. The paths through the fields are barely visible and our shoes, socks, and pants are being attacked by painfully prickly hitchhikers. We hope to flatten the paths as we go to the museum more often. Our temporary solution has been to wear flip flops because they have nothing to grab!

It takes about 15 minutes to walk to the museum from the dig house.
The path through the fields is barely visible.   

The culprit. 

The painful result.