Preparing samples for SEM-EDS analysis
This is the story of me learning the intricacies of the sample preparation process for the kind of material analysis I wanted to conduct.
About me
Catalhoyuk Research Project, East Mound North Shelter 2015 (Cursing at my tablet while trying to enter my data to start digitizing the unit I excavated on ArcGIS)
Hi there! My name is Duygu Ertemin. I am a Turkish archaeologist and my current curiosity is to explore digital scholarship tools for archaeological science communication. It is funny because 2015 Duygu would have never imagined we wrote the sentence above using the StoryMaps tool of ArcGIS! Learning ArcGIS for digital field recording was hard but learning something new is never easy from the beginning right?! Knowing this today, I decided to tell my story of learning the sample preparation process for the SEM-EDS pottery analysis I conducted for my MSc project.
Click on the marked cities on the map to explore more about my journey.
Sample preparation
On my first day at the lab in Athens, I took a look at the samples under an optical microscope and took several photos. It was helpful to see the fabrics of the pottery sherds so that I could decide what is of importance to sample and analyze.
On my second day, I picked 20 samples from a larger set of ceramic assemblages that were analyzed with Neutron Activation Analysis and started preparing my samples for analysis.
I was cutting out small blocks from the bigger pieces (the academic term for this technique is called cross section fracture) and smoothing the undecorated surfaces with sandpaper.
In the lab, I was told to take simple notes and to draw quick sketches following their lab guideline. According to this guideline I had to take the next letter and the number available from their list and assign those numbers to my samples as I record them.
You can see that my sample number 28 was assigned to line M9 and sample 29 to line M10. The second step after assigning these numbers/codes was to draw a quick sketch of my samples, show where I saw the decorated surfaces, and add any other notes I found important.
At first, I really did not understand why I was required to make those sketches. It felt like a very old-school way of recording after dealing with digital recording systems in the excavations, BUT I quickly understood the importance of it.
Take a look at the sketch I made for sample 36 (M11 15/36). You will see the sides I marked to indicate the red and the black decorated surfaces but also a random line on the right side of the sample between the decorated surfaces.
That line shows us the surface of this sample that will sit on the circular platform for the next step in the sample preparation process which is carbon coating.
Carbon coated samples
As you will see, after carbon coating the samples there is no way of telling which side is decorated red or black. That is why when we do the sketches we specify the side that our sample will sit on the stub so that we can understand the sides we are analyzing even several years after this initial analysis we can reanalyze a sample by following that simple sketch I made...
Self-reflection
The sample preparation process was the most fruitful part of my training at the National Research Center of Research in Athens.
I learned the importance of sample recording guidelines, capturing fabric images with optical microscopy using different magnification objectives, the working principles of SEM-EDS machines, and what to pay attention to during the sample preparation process to receive better imaging results and measurements.
I also learned that no question is a silly question. It initiates conversations, connections, and mutual understanding of diversity in knowledge surrounding archaeological materials.
