New Scientific Techniques to Measure Scroll Deterioration
Scientists at the Weizmann Institute in Rehovot, Israel have recently found ways to measure scientifically the amount of deterioration in the Dead Sea Scrolls. These measurements will be used to monitor the scrolls at the Israel Museum to insure that me further deterioration of the scrolls occurs.
The scrolls are written primarily on parchment prepared from animal skins—mainly sheep and goat. Parchment contains collagen which when exposed to excess heat or moisture tuns to gelatin.
Using an X-ray diffraction technique, Weizmann Institute scientists have developed a method for measuring semi-quantitatively the relative proportions of collagen and gelatin in parchment. The technique is, fortunately, nondestructive. Testing has no effect on the parchment being examined. The higher the ratio of gelatin, the greater the deterioration.
Scroll samples have been placed at various locations within the museum’s scroll area. Periodically these sample fragments will be examined for change in the collagen/gelatin ratio, which would indicate an unsafe environment for the scrolls.
In their study of the scrolls, the Weizman scientists found, not unexpectedly, that the darker borders of the scrolls had deteriorated the most and that the inner sheets were better preserved than the outer sheets. This suggests to the scientists that an external environmental agent, probably water, was responsible for the deterioration.
Said the scientific report, “The micro-environment around the inner portions of the scrolls themselves was probably particularly day as the outer layers probably trapped incoming water vapor.”
A more surprising finding, however, was that there seemed to be sharp boundary lines on the scrolls between high and low deterioration areas. These sharp boundaries were reflected both in the collagen/gelatin ratios and in another measure of deterioration based on the racemization of amino acids.a
That fact suggested to the scientists that major damage had occurred to the scrolls sporadically during limited time periods as a result of intermittent relatively high water-accumulation instead of a gradual deterioration from continued exposure to humidity. Continued exposure to humidity would produce gradual variations in the measures of deterioration used by the scientists, rather than the sharp boundaries of high and low deterioration which, in fact, were found in the scrolls.
The scientists also concluded that most of the deterioration, reflected in the change from collagen to gelatin, occurred many centuries ago, rather than in the relatively short period since the scrolls’ from the caves by the Dead Sea.
This was confirmed, said the scientists, by visual inspection of the scrolls: “A careful visual comparison of the photographs of scrolls taken soon after being unrolled 30 years ago with the same scrolls in January 1980, revealed no noticeable differences in the distribution of light and dark areas.”
(For further details, see Stephen Weiner, Zina Kustanovich, Emanuel Gil-Av and Wolfie Traub, “Dead Sea Scroll parchments: Unfolding of the collagen molecules and racemization of aspartic acid,” Nature, Vol. 287, p. 820 [October 30, 1980].)