Tuesday, 19 February 2013

Layers of time

Natasha K. Loeblich's winning image

I rarely make more than one post per day, but I just had to share this amazing image by researcher Natasha K. Loeblich, which was awarded a distinction in the 2008 Nikon Small World Photography competition. The image shows layers of paints in a colonial townhouse building, and Natasha's work has helped understand what the townhouse looked like during different periods of occupation, which can then be used for repairing historic buildings in an authentic style. You can read more about the research project here. The image was posted recently on io9 website, and many of the reader comments remarked how 'sparkly' the paint looks - it's suprising how materials can appear very different when viewed at the microscopic scale, and materials such as paints which may appear smooth and homogenous, are actually made up of different types of particles. Natasha is an art conservator and paint analyst with a background in architectural history, and her work demonstrates how much archaeology can learn from other disciplines. The techniques she uses (such as cross section analysis, SEM, FT-IR) are identical to those we use in archaeology, and even the application in this particular example is very similar. Her image shows a 'thick' section through the paint, whereas the Catalhoyuk image is a 'thin' section - the same thing really, except the thin section can be analysed using transmitted light, whereas a thick section is examined with reflected light. Both can be analysed further using chemical techniques if they are left without a glass coverslip.

Wall plasters from Building 1 at Catalhoyuk
The image reminded me of one of Dr Wendy Matthews' slides from a Neolithic building in Catalhoyuk (Building 1 for those of you who are familiar with the site); her research into wall plasters has helped understand how long buildings were occupied, how often they were redecorated, how clean they were kept, and how this changed over time. In the image to the right you can see how the layers vary from less frequent thicker, pale brown layers, interspersed with multiple sequences of fine 'grey' layers. These grey layers are actually marl based plaster, and appear much whiter at the macroscale. The large white areas in the thick layer are voids - spaces in the plaster matrix where there was once plant material (used as a temper), that has now decayed. These thick layers represent resurfacing of the walls, whilst the fine layers are plaster 'washes'. Check out Wendy's 2005 publication in the Catalhoyuk monograph for more info:

Matthews, W. (2005) Life-cycle and life-course of buildings. In: Hodder, I. (ed.) Catalhoyuk Perspectives: Themes from the 1995-9 Seasons. McDonald Institute for Archaeological Research and British Institute of Archaeology at Ankara, Cambridge

On a technical note, the Catalhoyuk image is presented the 'wrong way up' - as it is from a wall it should be at 90 degrees, but I wanted to show the similarity with Natasha's image.

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