Sunday, June 10, 2012

Falling Apart at the Seams


During the trip to Florence last weekend, I visited the Uffizi Gallery and saw incredible paintings by Botticelli, da Vinci, Michelangelo and many more. While all of the paintings were incredibly beautiful and famous, I was particularly struck by a temporary exhibit that we only saw by chance. It was the last day of the Tapestry Gallery, an exhibit on display for only a few weeks, in which seventeen antique tapestries were hung up for public viewing for the first time in twenty-five years. The tapestries had been removed from the Uffizi due to their degradation from light, temperature, and other environmental factors. The curators chose to hang restored pieces adjacent to ones that have not restored, highlighting how significant the damage fabric artworks experience can be. This juxtaposition was plainly obvious even to someone as ignorant of fabrics as me. The un-restored pieces were almost completely leeched of color, losing the incredibly intricate level of detail seen in the restored pieces. Alongside the tapestries, information about the degradation of fabric pieces over time and the restoration process was presented. I was unable to read about the entire process (getting to the bus station was a slightly more pressing issue) so I did some research and found that photochemistry, or light related chemistry, is the primary source of analytical tools used to investigate textiles.
            As discussed in class with regard to other art forms, the techniques used to study antique textiles must be non-invasive and non-destructive. Fluorescence spectroscopy has been particularly useful in recent years in determining the red plant based colors used to dye silks. Colorimetry, in which the colors of samples are quantified and compared through spectroscopy, is used for pre and post restoration comparisons.
Section of Christ Appears Before Herod produced in a Medici factory in the 16th century

            Not only can analytical techniques reveal information about the dyes in a tapestry but they can also reveal information about the dying process. It was discovered that when a mordant, which helps dyes to adhere to thread, was used along with the dye, the bonds between the thread and dye molecules were different. Based on the standards created then analyzed using spectroscopy and fluorimetry, a database has grown to compare ancient textiles to which indicates the dying process used in addition to just the dyes. These studies have also revealed how some dye compounds interact and bind with thread. For example, purpurin bonding to thread was determined to be through one hydrogen bond after it was found that purpurin was present as a monomer when mordant was not used while it was a dianion in samples with mordant.
Purpurin (a red/yellow dye)
Through chemical analysis, much can be discovered about ancient dyes and textiles. This information can then be used to prevent further damage by controlling the environment (light, humidity, heat, etc) where tapestries are stored. To see some more photos of the tapestries in the Uffizi exhibition, visit http://www.unannoadarte.it/arazzi/eng/arazzi-galleria.html.

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