Tuesday, February 27, 2007
Elsie Peck is sorting through the containers of pottery found this year. We save shards that are diagnostic, such as rims, bases, handles, or areas of especially fine painted decoration or maker's marks, for photography and drawing. When possible, a broken vessel will be re-joined with adhesive to make drawing or photography easier. Some ceramics have soluble salts in the ceramic fabric, which can be highly destructive. Usually, the washing process for the shards removes the salts, so these are generally not problematic at Mut.
Lisa Bruno, Objects Conservator
Saturday, February 24, 2007
Cleaning corroded metal objects is hard work. Think about it. Most metal objects (unless made of gold or silver) start out as ores, such as copper carbonate, or copper sulphate. In other words, objects made of metal start out as corrosion, and only after a lot of human intervention do they become metal objects. So, after several thousands of years of being buried in the soil, these metal objects want to revert back to corrosion. It goes without saying that, after discovered by an archaeologist, it usually takes a great deal of intervention on the part of the conservator to get to the metal surface. Yes, chemicals are one way to assist in changing the corrosion, so that it can be removed to possibly reveal a metal surface. Sometimes there is no metal core, below all of the corrosion. The object is completely mineralized. Mechanically removing the corrosion is also a safer, but often very time consuming and physically difficult process. At the site, this year we are trying a mild solution of EDTA (ethylene diamine tetra acetic acid) made basic with ammonia. It has proven to be helpful at softening the corrosion crusts, making the mechanical removal with a scalpel more effective, and safer. The solution turns blue as copper corrosion dissolves.
When the archaeologists register the finds, as Jaap is doing in this photo, it is much more useful to have an actual image on the coin, or other information that may help in dating a layer. This is why finding coins is often exciting, yet painful at the same time. Luckily however, unlike the corrosion that Jakki mentioned in her post on the Wadjet Figure, the corrosion crusts at the Mut Temple are mostly stable.
Lisa Bruno, Objects Conservator
Friday, February 23, 2007
North of Mut's 1st Pylon we're down to the lowest couses of brick in the Roman Period buildings as you can see in this picture looking west to the temple's East Porch.
Mud brick architecture can be complex to excavate, in part because it is sometimes difficult to distinguish between mud brick and the surrounding earth. In addition, people didn't always completely remove the foundations of old buildings when they built new ones, as is the case in the lower picture. In the upper photo, where the Mut Temple's 1st Pylon meets the East Porch, we have the mud brick border of the Porch's foundations and several phases of brick construction of (or against) the Pylon itself. Sorting this out is challenging.
In Temple A's Forecourt, just south of the massive remains of the north colonnade, we discovered the foundations of a small building made of mud brick and small sandstone blocks. To its east, in the rear of the photograph, workers are uncovering a large circular feature made of baked brick and stone that is full of burnt debris.
A general view south of the Forecourt near the end of the week. The stone and brick circle is on the left. The baked brick and ceramic-pipe drain running diagonally across the court is probably of the Roman Period.
While Jaap and our inspector, Mouna, take a break in the shade, Lisa and Khaled work on the coins we have found this season. Their ability to concentrate on this delicate work in the midst of all that is going on is amazing.
Here is one of the coins as found and after cleaning by Lisa and Khaled. Having the images and inscriptions this clear should make it relatively easy to date the coins.
We finally finished work on the small chapel just east of the Precinct entrance. Instead of taking a few days, it has taken a few weeks because the walls were in much worse condition than expected. On Saturday the granite sphinx will go on its new base west of the chapel where Lisa and Khaled can work on it.
With the small chapel out of the way, we were able to get back to the column in Chapel D that we couldn't complete last year. Here's how it looked at the end of the 2006 season. Jaap determined that the column segment on bricks belongs on this column but at a higher level than preserved. This year he found a second segment that joins the first.
Mohammed Gharib and his team cut new sandstone column drums to build the column up to the proper height.
On Thursday, with the new drums in place, Khaled, Jaap and Mohammed consult on the precise placement of the first ancient column segment.Thursday was Jaap's last day with us this season so we were glad he was able to see this project through to its final phase. The final step will be to build out the new section of column to the ancient circumference.
While column restoration goes on in Chapel D, we are beginning to take down an old baulk in the Taharqa Gate (background) in preparation for work there next season.
This week we had to contend not only with the heat but with this huge dust devil that blew through the precinct one morning. A dust devil this size can pick up small objects and even light chairs and toss them about.
Tuesday, February 20, 2007
Treatment of an Egyptian copper alloy statue of Wadjet
I just finished treatment on and helped install the Egyptian copper alloy statue of Wadjet. This object, along with many other Egyptian artifacts, are to be on display at the Brooklyn Museum in the Pharaoh’s Queens and Goddesses exhibition opening March 23rd. Conserving this object has been quite an interesting experience for me.
The primary concern with the statue was that it had some severe areas of bronze disease, pictured at right. Bronze disease is a destructive corrosion process that occurs from the reaction of chlorides on copper in the presence of moisture and oxygen. This type of degradation process produces bright green powdery spots of corrosion while simultaneously eating away at the metal. Once begun, this reaction is very difficult to stop unless one or more of the reacting compounds (chloride, water, oxygen) are removed.
Unfortunately, bronze disease occurs in many archaeological copper-alloy objects given that they often accumulate chlorides during burial. Once the objects are excavated, the moisture and oxygen present in the atmosphere can catalyze the destructive corrosion process. Preventive methods such as elimination of moisture in the form of environmental regulation can sometimes prevent the outbreak of bronze disease, however very often the object will need to be physically treated by a conservator. This was the case with the Wadjet statue.
For treating the statue for bronze disease I first mechanically removed the bright green copper corrosion products, primarily on the bottom of the statue, with small hand tools. Following this, the areas affected by corrosion were chemically treated with a corrosion inhibitor. The inhibitor reacts with the metal to form a stable surface. Preventive methods including reducing the relative humidity (moisture) have been introduced into the exhibition area to ensure that the bronze disease is abated. Pre-treatment and post treatment images of the bottom of the statue are pictured below. I know that Lisa is currently working on copper alloy coins on the dig, which may have the same type of corrosion problems. If so she will treat these coins in a similar manner.
During treatment of the statue, a modern plaster fill on the base of the figure’s throne was removed. This action was taken because the plaster was exacerbating the bronze disease by holding moisture at the metal surface. Upon removal of the plaster fill an exciting find was unearthed – an animal skeleton. See image below. After discussion with colleagues and some research, it was discovered that these bones might possibly be ichneumon or Egyptian mongoose bones. Some literature indicates that seated, bronze Wadjet figures, such as the one being discussed, were often used as coffins for ichneumon. The ichneumon, revered for its ability to kill snakes and crush crocodile eggs, became a sacred animal of the goddess Wadjet in the Late Period.Jakki Godfrey
Friday, February 16, 2007
Working on Site
Khaled and I spend much of our time on site, joining fragments. The purpose of this is so that inscriptions are more easily read and frankly, so that these often small fragments do not become lost. In an outdoor environment, we need to use a durable adhesive. In this case, we use an epoxy with a barrier layer of a more reversable adhesive. Making joins that are perfect can be tough.
Often the surfaces are so eroded, there are not good clean areas to join. Also, getting the right balance, so that the pieces stay together while the adhesive cures can be a challenge. At least in Egypt, there is enough sand to make many sandboxes to assist in this effort.
We have been cleaning the lintel in the conservaton laboratory at the Luxor Museum, where there is running water, electricity, and chairs. We have had the good fortune this week to go to the museum in the afternoons, avoiding the hot sun. With those basic services, we could take the cleaning to a certain level, and stabilize the very fragile paint and gilded surfaces. At the site, we do not have running water, or electricity and little shade, and since I'm having technical difficulties with the photographs, I'll talk about conservation on site in the next posting.
More of the same plus a few surprises
In Temple A we are uncovering the remains of the paving that led from the gate in the 1st Pylon (background) to the 2nd Pylon. We suspected this path was paved but now we've confirmed it.
Work on the north wall of the Forecourt is finished and Bill has begun the task of mapping it.
We are continuing to take down the structures built against the Mut Temple's 1st Pylon. The week's first surprise was the discovery of the actual plastered face of the pylon, just visible behind the meter stick. It projects several centimeters in front of the taller remains of the pylon, preserved by the structures built against it.
We also uncovered a neat, brick-bordered oval in the center of the western room, seen on the left in a view to the northeast. It is full of pottery that Qufti Abdel Aziz is removing piece by piece while other members of his team continue to work behind him.
Herman te Velde, expert in Egyptian religion and iconography, was able to join us for a few days this season. He, William and Jaap discuss the work while standing on the north wall of Temple A's Forecourt.
One of the monuments removed from the site by the SCA at the end of the previous week was this large limestone statue of Tuthmosis IV (re-used by Ramesses II) that stood against Temple A's 2nd Pylon.
When we cleaned the area in which it had stood, we discovered a large hole where the lower course of stone should be. To our surprise, we discovered that the core of the pylon is mud brick; the stone is only a facing. However, one of the blocks in the upper course was held in place mainly by the pressure of the blocks on either side. Repairing this hole immediately became a priority.
Our restorers got to work filling in the hole with stone and the compound we use in stone repair. New blocks were cut for the missing lower course of the pylon; the first to be put in place is visible in front of the workman above.
When the patch was complete, our stone restorer, Mohammed Gharib put the final touches on the new surface. Below, the finished product. Mohammed's earlier repair to the north wall of Temple A's Forecourt can also be seen. He's a superb craftsman.
Talk about a flash from the past: pharaonic reliefs show stones being dragged on sledges, just as these workmen are doing. This block will be used in the new base for the granite sphinx behind them . The foundations for the base were being dug as the block was dragged in.
The work on those foundations provided the week's final surprise: in the last hour of work yesterday, we came on a large piece of black stone. Our foreman, Farouk Sharid Mohammed, supervises the excavation personally.
Here's the stone as it came out of the ground. It turns out to be the lower legs and feet of yet another Sakhmet statue, with the epithets preserved on one side. We'll clean it and stand it up on Saturday.
The week ended on a high note. Conservation work on the lintel is complete and it looks splendid, particularly the 5 gilded child gods. Lisa, Khaled and the Luxor Museum conservators have done a wonderful job. Congratulations!