Tuesday, August 11, 2015

Conservation Tips and Tricks

As the excavation season progresses, it isn't uncommon for some tools and materials to become scarce as supplies are used up.  In our case, certain cleaning tools employed by the conservators were no longer available.  In a display of ingenuity, student intern, Vale Vafaei, began experimentation with the existing supplies to make her own Dremel polishing tools for the removal of light surface debris on copper alloy objects.  This was accomplished by adhering polyethylene foam to used Dremel bits and cutting them into the required shapes.  The results were both elegant and effective.  


Thursday, August 6, 2015

2015 Excavation Season well under way!

This year's field conservation staff for Kaman Kalehoyuk is comprised of Nichole Doub, Ingrid Gudmestad and Vale Vafaei.  We have been hard at work over the last 4 weeks conserving the artifacts recovered from this year's excavation and diffing into the backlog from previous seasons.


Here are just a couple of the objects we've been working on so far.... 

       
















There has also been vast quantities of x-radiography taking place....


Even a couple of block lifts on site...


And there is sure to be more excitement and work in the next few weeks!


Saturday, August 2, 2014

An Iron Age Painted Sherd

While we work primarily with metals in the Kaman conservation lab, we had a particularly lovely painted sherd come through the other week. This sherd was excavated from an Iron Age level at Kaman Kalehöyuk and is typical of the painted ceramics from that period. It was found broken in two and the painted design was partially obscured by soil and surface concretions.

Conservation Intern Claire D'Izarny first cleaned off the soil using cotton swabs wetted with deionized water and then removed the concretions by scalpel. While cleaning the sherds, Claire decided to make use of our Dino-lite USB microscope to show what it is like to do this delicate work under the microscope.  


Here are photos taken with the Dino-lite showing a detail of the painted design before and after removing the concretions.


Now that the painted sherd has been cleaned and re-assembled, it can be drawn, photographed, and studied!

Friday, August 1, 2014

New X-Ray Machine for the Kaman Conservation Lab!

Some exciting new equipment arrived in the Kaman Conservation lab this year- a Faxitron digital cabinet X-ray machine! Thanks to the support of the Commemorative Organization of the Japan World Exposition ('70) and the Türkiye İş Bankası, which helped fund the purchase of this equipment, we can now x-ray a wide range of objects. This will be especially useful to investigate metal finds with thick corrosion and small block lifts prior to micro-excavation.


Our x-ray machine can fit objects up to approximately 15 x 18 x 18 inches; however, the digital sensor at the bottom of the cabinet is 9 x 11.5 inches, limiting what we can x-ray at any one time to that size. Since our unit has a digital x-ray sensor, we don’t have to use x-ray film or plates- which is the reason this type of radiography is called 'direct radiography'. Our Faxitron (model 43855) goes up to 130 kV, and is semi-automatic- meaning we control the camera/sensor from the computer but we have to set the kV and turn the x-ray source on and off directly on the Faxitron cabinet.


Our new protocol is to x-ray all of our small metal finds prior to treatment. This is incredibly useful as it allows us to better understand the shape and condition of an object when bulky corrosion is present, sometimes helping us to detect an original surface. X-ray imaging also aids in the decision-making for treatment, and assists the conservator in the investigative cleaning process. For example, prior to treating this copper alloy object, identified as a stamp, conservation intern Claire D’Izarny  took an x-ray with the new Faxitron. The design on the face of the stamp showed up clearly in the x-ray and helped Claire understand where to clean away the corrosion and burial soil obscuring the design.



While we love our new tool, we are still exploring the different applications for our machine. We hope to post any exciting finds and updates here and we would love to hear about other people’s experiences with similar machines! In the meantime, here are some more x-rays for your viewing pleasure...






Monday, September 9, 2013

Changing Out the Silica Gel




Silica gel is a form of silicon dioxide (SiO2) with an expansive microscopic pore structure that provides a large internal surface area capable of absorbing and desorbing water molecules. It has been widely used as a desiccant for food and other goods since the beginning of the 20th century. Because art objects require a stable environment, the museum world uses silica gel to control the relative humidity (RH) in exhibition cases and in storage. At Kaman Kalehöyük silica gel is used in storage containers to stabilize the RH. The gel is most often used to create a low humidity environment (≤ 30%) for metal objects, because many of the primary deterioration reactions for metals involve water.


 


An important part of the conservation work at Kaman Kalehöyük is re-conditioning and replacing the silica gel in storage. Some of the granules are doped with a moisture indicator (cobalt(II) chloride) that  gradually changes color from blue to pink when it transitions from the anhydrous  to the hydrated  state.  Pink silica gel is removed from the storage containers and reconditioned in the oven. Once it has returned to the anhydrous (blue) state, the silica gel can be returned to the many storage containers. 

Friday, August 16, 2013

Making Seal Impressions

Over the last few weeks we've been making impressions of seals. At Kaman-Kalehöyük, the types of seals that are usually excavated are flat, disc-shaped impressions with a raised or incised design on clay, stone, or metal. In antiquity, these would have been found on containers or communications to demonstrate that they had not been tampered with before they had reached their destinations.

To make these seal impressions, we've been using Sculpey, which is a brand of polymer clay made by Polyform Products in the United States. It can be easily molded and put into a conventional oven to harden. This will allow us to better understand the surface detail, especially of the seals.


First, we worked the Sculpey until it sufficiently softened. Then, we roll the Sculpey into a ball. We usually do a minimum of two impressions of each. This allows us to get the best possible result from the impression.

Conservation intern Davina is working the Sculpey in preparation of molding.

The balls are then flattened slightly and pressed against the surface from which we want to take the impression. The Sculpey is then peeled away from the surface gently.


We then line the baking tray with aluminium foil and place the Sculpey impressions on the foil. The Sculpey goes into the oven at 135°C for 15 minutes, as per the instructions on the packet.

 

When we are done taking impressions of the object, we clean the residue off the surface using some acetone.


Monday, August 5, 2013

Collaborating with Osteoarchaeologists



A cluster of small finds was excavated recently, including some bronze fragments and a green bone. In order to further investigate the possible relationship between these objects, Kaman Kalehöyük conservators sought the expertise of Cheryl Anderson, a PhD student in anthropology at the University of Nevada Las Vegas. Cheryl began by explaining how human bones differ from other mammals and concluded that the bone was a rib of a medium size mammal like a goat or a dog. 



Buried bone often takes on the color of the surrounding soil; conservators are able to elaborate on the scientific aspects of this particular phenomenon. The green color of many excavated metals can be attributed to copper corrosion products (such as copper carbonates, copper hydroxides, copper sulfates, etc.), which form on the surface as copper alloys deteriorate.  Many of these minerals are excellent colorants and certain compounds, like malachite (Cu2CO3(OH)2), have been used as green pigments in paints from ancient times. Because it was buried near these bronze fragments, the bone was stained by the green corrosion products as the copper alloys deteriorated.