Archaeological Sites as Physicochemical Systems - ACS Publications

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Archaeological Sites as Physicochemical Systems Macroarchaeometry of the Tomb of Nefertari, Valley of the Queens, Egypt G. Burns, Κ. M. Wilson-Yang, and J. E. Smeaton Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 1A1, Canada

Major archaeological monuments are considered macroarchaeometrically as physicochemical systems coupled to their environment and surroundings. These edifices can be studied with the tools of analyt ical, environmental, and physical chemistry, as well as those of re lated disciplines. One of the aims of macroarchaeological chemistry is to identify the principal physicochemical processes in archaeolog ical systems. This approach is illustrated by studies in the tomb of Nefertari, Valley of the Queens, Egypt, which now exists in a desic cated, fragile state. As a first step, a computerized hygrothermograph coupled to a minicomputer was developed and placed in the closed tomb. This instrument can make measurements for 1 year. Four processes that affect the humidity of the tomb were identified. In a parallel set of experiments, samples collected from the tomb were analyzed. The results were compared with those of an analysis of plaster from the tomb of Horemheb, Valley of the Kings. A tentative plan for the reconstruction, restoration, and conservation of Nefer tari's tomb is proposed.

TTHE TECHNIQUES

OF CONSERVATION a n d conservation science

a n d the

techniques of anthropology, archaeology, a n d art history are often used to solve v e r y specific p r o b l e m s s u c h as the r e m o v a l of efflorescent materials f r o m the surface of a w a l l p a i n t i n g or the d e t e r m i n a t i o n o f the p r o v e n a n c e

0065-2393/89/0220-0289$06.50/0 © 1989 A m e r i c a n C h e m i c a l S o c i e t y

Allen; Archaeological Chemistry IV Advances in Chemistry; American Chemical Society: Washington, DC, 1989.

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ARCHAEOLOGICAL CHEMISTRY

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of pottery. A l t h o u g h this approach is often v e r y effective, specific p r o b l e m s are o n l y components o f a larger p i c t u r e . E a c h m o n u m e n t , site, object, o r any other archaeological system exists i n d y n a m i c p h y s i c o c h e m i c a l i n t e r action w i t h its e n v i r o n m e n t , as defined b y a c o m p l e x a n d c h a n g i n g set o f conditions. T h e s e conditions m a y b e c h e m i c a l , c l i m a t i c , geological, geographical, o r p h y s i c a l . I n some cases, changes i n these conditions m a y b e dramatic, s u c h as those o c c u r r i n g i m m e d i a t e l y after excavation o f a n a r chaeological m o n u m e n t w h e n i t undergoes a severe ecological shock o r as a result o f some natural o r h u m a n - m a d e catastrophe. T h e identification o f these conditions is one o f the p r i m a r y tasks o f archaeometry, a d i s c i p l i n e i n w h i c h the methods of the natural sciences are u s e d to i n t e r p r e t archaeological or conservation science data. I n a m u l t i d i s c i p l i n a r y field s u c h as archaeometry, archaeological c h e m i s t r y occupies a c e n t r a l role because its various branches i n c l u d e analytical, c o m p u t a t i o n a l , a n d p h y s i c a l c h e m i s t r y , as w e l l as c h e m i c a l physics ( F i g u r e 1 ) .

Macroarchaeometry M a c r o a r c h a e o m e t r y , the study o f a r c h a e o l o g i c a l - p h y s i c o c h e m i c a l systems w i t h t h e i r s u r r o u n d i n g s (J), provides a m o r e c o m p r e h e n s i v e approach to investigations o f ancient materials. M a c r o a r c h a e o m e t r i c investigations, w i t h t h e i r c e n t r a l core o f macroarchaeological c h e m i s t r y , are p a r t i c u l a r l y useful i f the p h y s i c a l size o f a n archaeological system is large; a p h y s i c a l l y large system makes i t possible to identify t i m e - a n d space-dependent p h y s i c o c h e m i c a l gradients w i t h i n the system. H o w e v e r , n o sharp d i v i d i n g l i n e exists b e t w e e n archaeometry a n d m a croarchaeometry, o r b e t w e e n archaeological c h e m i s t r y a n d macroarchaeological c h e m i s t r y , because t h e effect o f t h e e n v i r o n m e n t m a y b e m o r e

MACROARCHAEOMETRY (System and Surroundings)

CONSERVATION CONSERVATION SCIENCE (Stabilization of materials in situ, in vitro)

ARCHAEOLOGICAL CHEMISTRY ARCHAEOMETRY

i

(System Conditions)

ART

HISTORY

ANTHROPOLOGY ARCHAEOLOGY (fundamental data )

MULTIDISCIPLINARY BACKGROUND Figure 1. Interrelationship

between archaeological chemistry and other fields of study.


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i m p o r t a n t i n one system t h a n i n another. I n some eases, the i n t e r a c t i o n of an archaeological system w i t h its e n v i r o n m e n t m a y be n e g l i g i b l e , a n d stand a r d archaeometric techniques can b e r e a d i l y a p p l i e d . I n other cases, such as the study of large archaeological m o n u m e n t s that cover square k i l o m e t e r s of area a n d that interact i n a c o m p l e x m a n n e r w i t h the e n v i r o n m e n t , a c o m p r e h e n s i v e macroarchaeometric approach is n e e d e d . I n any case, macroarchaeometry provides u n d e r s t a n d i n g of the f u n d a m e n t a l mechanisms i n historical m o n u m e n t s ; these mechanisms manifest themselves as specific p r o b l e m s . P r o b l e m s such as accelerated degradation or l o n g - t e r m c h e m i c a l reactions l e a d i n g to compositional change are exp l a i n e d a n d can therefore b e dealt w i t h m o r e successfully. T h e macroarchaeometric approach is e v i d e n t i n various chapters of this v o l u m e ; the i m p o r t a n c e of the macroarchaeometric c o m p o n e n t varies from case to case. T h e processes of degradation i n bones a n d t e e t h (2) a n d i n fibers (3) are discussed w i t h respect to b u r i a l e n v i r o n m e n t s . T h e processes of radiogenic a n d t h e r m a l l y d e r i v e d free-radical p r o d u c t i o n i n solids (4, 5) a n d a m i n o a c i d r a c e m i z a t i o n (6, 7) also d e p e n d o n the system a n d the e n v i r o n m e n t i n w h i c h t h e y are s t u d i e d . T h e macroarchaeometric approach has w i d e applicability. C l i m a t i c s t u d ies i n the caves of Lascaux, F r a n c e (8), a n d A l t a M i r a , Spain (9), are b u t two examples. T h i s approach is n o w particularly useful i n studies of the excavated a n d unexcavated ancient sites of the N i l e R i v e r V a l l e y because of the recent, accelerated d e t e r i o r a t i o n o f m a n y o f its m o n u m e n t s . It has already b e e n a p p l i e d to several ancient E g y p t i a n archaeological sites (10-21).

Recent Environmental Changes in the Nile Valley T h e c l i m a t e of the N i l e V a l l e y was stable a n d p r e d i c t a b l e p r i o r to the c o n struction of the A s w a n h i g h d a m . A l t h o u g h the effects of a n n u a l i n u n d a t i o n s w e r e r e m o v e d w i t h the construction of the d a m , the e n s u i n g c l i m a t i c changes u s h e r e d i n a n e w set o f p h e n o m e n a that threaten the N i l e B a s i n a n d its p e o p l e , from A l e x a n d r i a to A s w a n . O u r investigations (to b e p u b l i s h e d ) indicate that, because of overall increased i r r i g a t i o n , this threat n o w extends as far south as K h a r t o u m . T h e s e adverse p h e n o m e n a i n c l u d e increases i n soil salinization ( I I , 12), relative h u m i d i t y , a n d rainfall. S u c h changes make ancient E g y p t i a n sites more v u l n e r a b l e to t h é ever-present danger of seismic activity, w h i c h is expected to increase because of the i n t e r a c t i o n of annual w a t e r l e v e l changes i n the A s w a n r e s e r v o i r a n d the fault zones of the N i l e V a l l e y (22). C o n s e q u e n t l y , the establishment o f the macroarchaeometric p h y s i c o c h e m i c a l c o n ditions of E g y p t i a n archaeological sites located at a distance of m o r e t h a n 1500 k m along the N i l e R i v e r is b e c o m i n g increasingly i m p o r t a n t . I n this chapter, w e illustrate these points w i t h a r e p o r t o n o u r studies, u s i n g m a croarchaeological c h e m i s t r y m e t h o d s , of the p h y s i c o c h e m i c a l processes i n the t o m b of N e f e r t a r i a n d t h e i r consequences for its conservation.


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Physical Condition of Nefertari's Tomb T h e t o m b of N e f e r t a r i ( n u m b e r 66, V a l l e y of the Q u e e n s , T h e b e s , U p p e r E g y p t ) is a designated E g y p t i a n national treasure. It was constructed app r o x i m a t e l y 3250 years ago for the favorite q u e e n of Ramesses II (23). Its w a l l paintings are n o t e d i n t e r n a t i o n a l l y for t h e i r s t r i k i n g design a n d are an excellent example of E g y p t i a n art and technology at the height of t h e i r d e v e l o p m e n t d u r i n g the 19th dynasty. I n a large p o r t i o n of the t o m b , the murals are still r e l a t i v e l y intact, u n p e r t u r b e d over the m i l l e n n i a . T h e y have r e t a i n e d t h e i r colors a n d appear m o r e attractive than the murals i n m a n y other ancient tombs i n E g y p t ; e v e n i n the V a l l e y of the K i n g s , m a n y m u r a l s have suffered severe damage because of the c h a n g i n g e n v i r o n m e n t a n d h u man intrusion. A f t e r its discovery a n d early repair i n 1904 (24), the t o m b b e c a m e a w e l l - k n o w n tourist attraction, a n d reproductions of its murals w e r e p r o m i n e n t l y d i s p l a y e d i n early guidebooks (25, 26). It a c q u i r e d such e m i n e n c e that today E g y p t i a n tourist posters are often reproductions of its various murals. T h e t o m b was cut from v e r y p o o r q u a l i t y limestone that is v e i n e d w i t h s o d i u m c h l o r i d e . S o m e of these veins are several meters l o n g a n d about 2 c m t h i c k . T h e walls of the t o m b w e r e p l a s t e r e d w i t h a 3 - 5 - e m - t h i c k mortar, c a r v e d i n l o w relief, a n d coated w i t h a t h i n w h i t e layer (27). F r o m recent carbonate analyses, w e f o u n d that this t h i n w h i t e layer consists of c a l c i u m carbonate w h i t e w a s h . T h i s w h i t e w a s h was p a i n t e d d u r i n g the final stages of the tomb's construction. A l m o s t a l l decoration remains i n the u p p e r chambers of the t o m b , whereas there are areas of massive loss i n the l o w e r chambers. T h e paint film, w h e r e it exists, appears to b e i n good c o n d i t i o n , b u t i n damaged areas, the l a y e r is e i t h e r b r o k e n or destroyed ( F i g u r e 2). T h e s u p p o r t i n g plaster has lost its cohesion, a n d s o d i u m c h l o r i d e crystals are v i s i b l e throughout the t o m b . S o m e crystals are as large as 1 c m ( F i g u r e 3). S o m e parts of the t o m b are c o v e r e d b y smaller crystals that sparkle u n d e r i l l u m i n a t i o n . T h e g y p s u m based plaster was d e h y d r a t e d t h r o u g h the loss of c h e m i c a l l y b o u n d water (27-29). Because the t o m b was d i s c o v e r e d i n an already fragile state, it is clear that this d e h y d r a t i o n took place over an e x t e n d e d p e r i o d p r i o r to 1904. T h e t o m b of N e f e r t a r i is therefore sensitive to perturbations i n t e m p e r a t u r e a n d especially sensitive to changes i n h u m i d i t y , w h i c h affect the m o v e m e n t of s o d i u m c h l o r i d e a n d m a y i n d u c e changes i n the d e h y d r a t e d plaster. O n the basis of w r i t t e n descriptions (24, 2 9 , 30), photographs (23, 24, 30), a n d p h y s i c a l e v i d e n c e , the e v o l u t i o n of the t o m b s c o n d i t i o n as a f u n c t i o n of t i m e can b e traced. P r e l i m i n a r y progress i n this d i r e c t i o n has b e e n made (28). T h e r e is no evidence of smoke deposits o n the walls, a fact that i m p l i e s that the t o m b was n e v e r i n h a b i t e d . T h e c o m p l e t e absence of any C o p t i c or A r a b i c graffiti suggests that the t o m b was not often v i s i t e d at the t i m e w h e n m a n y E g y p t i a n tombs u n d e r w e n t p a r t i c u l a r l y p r o n o u n c e d deterioration b e -



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Figure 2. Paint layer damage in the tomb of Nefertari. The image recorded on a 35-mm negative is one-third that of the original.

Figure 3. Salt crystal from the ceiling in the tomb of Nefertari. The image recorded on a 35-mm negative is the actual size.


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cause o f such h u m a n activities. T h e t o m b has b e e n r o b b e d i n a n t i q u i t y a n d flooded p r o b a b l y m o r e t h a n once i n its history, b u t it t h e n r e m a i n e d largely isolated, p h y s i c a l l y a n d c l i m a t i c a l l y (28), from the external e n v i r o n m e n t u n t i l its discovery i n 1904 (24).


Progressive Deterioration of the Tomb T h e c o n d i t i o n of the murals at the t i m e of the tomb's discovery i n 1904 (24) appeared d e c e p t i v e l y s i m i l a r to t h e i r c o n d i t i o n i n 1980, w h e n o u r group began its studies (28). H o w e v e r , the t o m b exists i n a desiccated state, is v e r y fragile, a n d is therefore p a r t i c u l a r l y susceptible to ecological changes; loss a n d fragmentation of the paintings i n the N e f e r t a r i t o m b are e v i d e n t ( F i g u r e 2 ) . T h e t o m b n o w r e q u i r e s d e t a i l e d macroarchaeometric studies because its future is v e r y m u c h i n f l u e n c e d not o n l y b y the p h y s i c o c h e m i c a l processes w i t h i n , b u t also b y m i n u t e , subtle interactions w i t h the e n v i r o n m e n t , i n c l u d i n g n e a r b y i r r i g a t e d fields a n d the N i l e R i v e r situated about 5 k m away ( F i g u r e 4). Progressive d e t e r i o r a t i o n o c c u r r e d i n the t o m b after its discovery, a n d one of us ( G . B.) f o u n d e v i d e n c e i n the t o m b that partial restoration was a t t e m p t e d i n 1935 to r e t a r d this deterioration. I n about 1940, the E g y p t i a n A n t i q u i t i e s O r g a n i z a t i o n ( E A O ) assessed the c o n d i t i o n of the t o m b because of startling changes w i t h i n i t . Salt crystals w e r e e v i d e n t , no m e n t i o n of w h i c h was made i n 1904 (24). Plaster s w e l l i n g a n d the collapse of m u r a l fragments

Figure 4. Schematic map of the Thebes-Karnak area. Point 1, the tomb of Nefertari; point 2, the tomb of Horemheb; and point 3, the position of the external hygrothermograph.



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w e r e also seen (30). A series o f photographs a n d carefully annotated drawings was p u b l i s h e d i n 1942 (30) that h i g h l i g h t e d the areas of postdiscovery loss a n d p o t e n t i a l loss o n the basis of the original photographs of 1904 (24). T h i s e v i d e n c e i n d i c a t e d that d e t e r i o r a t i o n h a d accelerated d u r i n g the p e r i o d o f frequent h u m a n e n t r y after 1904. Soon after this assessment, the t o m b of N e f e r t a r i was closed, l o c k e d , a n d sealed as a result of the justifiable c o n c e r n of the Ε A O . Thereafter, the deterioration of the t o m b s l o w e d , as e v i d e n t from a c o m p a r i s o n of observations made 1971 (23) a n d photographs taken i n 1981 (28, 31) w i t h photographs taken i n 1904 (24) a n d 1942 (30). T h e r e are historic reports of floods i n the area (32; J . R u t h e r f o r d , p e r sonal communication) a n d of a n earthquake i n 18 B . C . (33). T h e m o v e m e n t of the expansive E s n a shale b e d formation that u n d e r l i e s the w h o l e area is also a source o f d i s r u p t i o n (32). T h e E s n a shale b e d formation, w h i c h contains m o n t m o r i l l o n i t e clay, swells u p o n h y d r a t i o n b y about 1 2 . 5 % (32). T h e r e f o r e , i f a n adequate a m o u n t of w a t e r is available, for example f r o m i n c r e a s e d i r r i g a t i o n , h u m i d i f i c a t i o n , or flooding, the m o v e m e n t of this shale f o r m a t i o n accelerates. C o l l e c t i v e l y , these dramatic natural events are the most p r o b able causes of the loss of plaster a n d p a i n t e d murals i n the l o w e r c h a m b e r of the t o m b p r i o r to its discovery, a n d they increasingly (32) threaten tombs i n the T h e b e s area. To assess the p h y s i c o c h e m i c a l processes i n Nefertari's t o m b , to identify the mechanisms of its d e t e r i o r a t i o n , a n d to propose a feasible scheme for its conservation a n d restoration, the Inspector G e n e r a l of the Ε A O , H i s h m a t M e s s i h a , u r g e d o u r group to b e g i n investigations. A p e r m i t to o b t a i n r e p resentative samples from the t o m b a n d its e n v i r o n m e n t was issued to us b y the Ε A O i n 1980, a n d subsequently, our w o r k was i n i t i a t e d (28).

Long-Term Studies of Temperature and Humidity T h e p h y s i c a l c o n d i t i o n of the t o m b indicates that the p r i m a r y p h y s i c o c h e m ical processes of the t o m b are i n t i m a t e l y c o n n e c t e d to its i n t e r n a l c l i m a t i c conditions (28). I n an i n i t i a l study i n D e c e m b e r 1977, a set of h u m i d i t y measurements taken i n the closed t o m b for 1 w e e k w i t h an u n a t t e n d e d c l o c k w o r k h y g r o t h e r m o g r a p h s h o w e d a r e m a r k a b l y stable i n t e r n a l t e m p e r ature of 27 ± 1 °C; the i n t e r n a l relative h u m i d i t y ( R H ) was 31 ± 2 % . S m a l l increases i n h u m i d i t y that w e r e correlated w i t h e n t r y w e r e also r e p o r t e d (28, 31). O n e of the i m m e d i a t e i m p l i c a t i o n s of this latter finding is that any m e a s u r e m e n t o f h u m i d i t y t a k e n w h i l e the i n d i v i d u a l taking the m e a s u r e m e n t is p h y s i c a l l y present i n the t o m b does not reflect the t r u e c l i m a t i c conditions i n the u n d i s t u r b e d t o m b . T h e r e f o r e , h y g r o t h e r m o g r a p h i c data taken c o n c u r r e n t l y w i t h conservation w o r k d o not p r o v i d e i n f o r m a t i o n about the c o n ditions that s h o u l d be a c h i e v e d a n d subsequently m a i n t a i n e d i n the c o n s e r v e d t o m b . C o n s e q u e n t l y , before any conservation w o r k is b e g u n , i t


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w o u l d first b e necessary to gather p h y s i c o c h e m i c a l data w i t h m i n i m u m h u m a n interference. A s a first step t o w a r d data collection w i t h little h u m a n interference, an automatic h y g r o t h e r m o g r a p h interfaced w i t h a m i n i c o m p u t e r was d e v e l o p e d i n o u r laboratory to study the i n t e r n a l climate of the t o m b . T h i s i n s t r u m e n t can take t e m p e r a t u r e a n d h u m i d i t y measurements e v e r y 33 m i n for 1 year a n d store the data i n a c o m p u t e r m e m o r y . Its sensitivity to h u m i d i t y fluc tuation exceeds that of c o n v e n t i o n a l chart hygrothermographs b y a factor of 5. T h e r e f o r e , the i n s t r u m e n t has an i m p o r t a n t advantage over a c l o c k w o r k h y g r o t h e r m o g r a p h because it provides information o n l o n g - t e r m c l i m a t i c fluctuations i n the t o m b . Thermal Stability of the Tomb. T h e self-contained h y g r o t h e r m o g r a p h was left i n the t o m b of N e f e r t a r i i n F e b r u a r y 1981 for 1 year (34). T h e t e m p e r a t u r e a n d h u m i d i t y data for the 1-year p e r i o d w e r e correlated (Figures 5 a n d 6) w i t h external data taken near the N i l e R i v e r at K a r n a k ( F i g u r e 4). T h e N i l e R i v e r data w e r e obtained i n 1981 b y M . C . T r a u n e c k e r , a research c h e m i s t w i t h the F r a n c o - E g y p t i a n C e n t r e for Studies of the T e m p l e s at K a r n a k . F i g u r e 5 shows average m o n t h l y h i g h a n d l o w temperatures near the N i l e R i v e r at K a r n a k a n d the m o n t h l y average temperatures inside the t o m b . T h e results dramatically c o n f i r m the t e m p e r a t u r e stability of the t o m b r e -

Figure 5. Average monthly high (Δ) and low (•) temperatures in the Nile Valley and average monthly temperature (o) in the tomb. Where error bars are not shown, the standard deviation is less than or equal to ± 0.5 °C.



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p o r t e d e a r l i e r (28) a n d n o w show that the stable t e m p e r a t u r e is m a i n t a i n e d over a longer p e r i o d . T h e y e a r l y average t e m p e r a t u r e i n s i d e the u n p e r t u r b e d t o m b is 28.5 ± 0 . 5 °C, a n d the y e a r l y average h u m i d i t y is 7 ± 2 g of H 0 / m or 25 ± 6% R H at 28 °C. (Values are means ± standard deviations, unless otherwise stated.) (34, 35). T h e inhospitable i n t e r n a l climate of this t o m b has b e e n t h e r e b y q u a n tified. T h e v e n t i l a t i o n i n the t o m b is poor; it is difficult to w o r k i n this closed u n d e r g r o u n d m o n u m e n t for m o r e than 1 or 2 h because of the lack of fresh air a n d the a c c u m u l a t i o n of carbon dioxide p r o d u c e d b y r e s p i r a t i o n . These difficult conditions have p r o s c r i b e d p r o l o n g e d h u m a n visitation of the t o m b i n the past a n d at present a n d explains h o w s u c h a fragile m o n u m e n t s u r v i v e d into this c e n t u r y . 2

3

Cyclical Humidity Changes in the Tomb. T h e i s o t h e r m a l nature of the t o m b simplifies its p h y s i c o c h e m i c a l d e s c r i p t i o n because one k e y v a r i able is n o w fixed. T h e h u m i d i t y data d i d not show the same degree of stability as the data for t e m p e r a t u r e d i d . F i g u r e 6 shows that the external h u m i d i t y peaks i n J u l y . T h e i n t e r n a l h u m i d i t y follows this t r e n d b u t peaks 1.5 months later at a value of 9.1 g of H 0 / m or 3 2 % R H at 28 °C. T h e s e data suggest an a n n u a l cycle, a n d these results indicate that the t o m b of N e f e r t a r i is not totally isolated, e v e n i f it is closed, b u t that it is w e a k l y c o u p l e d to the external e n v i r o n m e n t . C o n s e q u e n t l y , the t o m b is progressively h u m i d i f i e d , as is the e n t i r e N i l e V a l l e y . 2

3

F i g u r e 7 is a plot of i n d i v i d u a l t e m p e r a t u r e a n d h u m i d i t y measurements for M a r c h 1981. T h e average temperature for this m o n t h was 28.2 ± 0.3 °C,



298


Figure 7. Temperature and humidity inside the tomb of Nefertari for 1981.

March

a n d the average h u m i d i t y was 16 ± 1% R H or 4.3 ± 0.4 g of H 0 / m . T h e t e m p e r a t u r e c u r v e shows the r e m a r k a b l e t i m e invariance already n o t e d i n the yearly data, h o w e v e r , the h u m i d i t y c u r v e is complex. T w o distinct features are e v i d e n t i n the h u m i d i t y data. T h e first is the appearance o f c y c l i c a l h u m i d i t y variations. T h e s e variations have a p e r i o d of about 1 day a n d lag b e h i n d the external cycles b y about 12 h . T h e s e cycles are e v i d e n t t h r o u g h o u t the f u l l set of a c c u m u l a t e d h u m i d i t y data, a n d they indicate that the closed a n d l o c k e d t o m b of N e f e r t a r i is not totally isolated from the outside, e v e n on a d a i l y basis. 2

3

T h e second feature is the appearance i n the data of sharp peaks f o l l o w e d b y slow decays. W e have d e f i n i t i v e l y c o r r e l a t e d most of these peaks w i t h h u m a n e n t r y , a n d c i r c u m s t a n t i a l evidence strongly suggests that a l l are, i n fact, caused b y h u m a n e n t r y . T h e e n t r y of e v e n a single p e r s o n produces a p r o n o u n c e d a n d a b r u p t change i n h u m i d i t y . S e v e n t e e n s u c h peaks w e r e r e c o r d e d o n the h y g r o t h e r m o g r a p h over a p e r i o d of 8.5 months. T h e r e w e r e b a r e l y detectable positive t e m p e r a t u r e peaks o f approximately 0.14 °C, lasti n g for 1 h o n average, that w e r e associated w i t h these entries. N o n e of the t e m p e r a t u r e peaks was of sufficient absolute m a g n i t u d e o r l e n g t h to alter the basic i s o t h e r m a l c o n d i t i o n of the t o m b . A p r e l i m i n a r y value for the rate of w a t e r vapor r e m o v a l i n the closed t o m b was calculated f r o m these peaks b y fitting the first five or six points of the slow decays to a pseudo-first-order rate law. T h e rate constant was approximately 5 X 10 m i n " . F r o m these data, it is possible to estimate quantitatively the effects of h u m a n e n t r y o n the atmospheric water v a p o r 3

1


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content of the t o m b . W e have estimated the rate of w a t e r vapor p r o d u c t i o n p e r p e r s o n , from the i n i t i a l increases of the e n t r y curves, to be 0.013 g of H O Z m p e r p e r s o n p e r m i n at 28 °C. I f 10 p e o p l e e n t e r e d the t o m b a n d stayed for 30 m i n , the increase i n water vapor w o u l d be 4.0 g of H 0 / m . T h i s value represents an increase of 14% R H at 28 °C. It w o u l d take 12 h for the absolute w a t e r vapor content to fall to w i t h i n 0.1 g of H 0 / m of its i n i t i a l value i f the w a t e r w e r e s i m p l y r e m o v e d at the m e a s u r e d rate. 2

3

3

2


2

3

T h e exact mechanisms for the r e m o v a l o f artificially i n t r o d u c e d w a t e r vapor i n v o l v e several p h y s i c o c h e m i c a l processes a n d have not yet b e e n firmly d e f i n e d . W e are c u r r e n t l y investigating the w a t e r adsorption characteristics of the t o m b as a w h o l e , b y u s i n g rates a n d rate constants for the data o n water r e m o v a l that w e gathered from 1981 to 1982. T h e existing v e n t i l a t i o n rates of the t o m b w i t h its d o o r closed are also b e i n g calculated.

Chemical Analyses T h e effect of a d s o r b e d water v a p o r o n the t o m b of N e f e r t a r i d e p e n d s , i n part, o n the materials used i n its construction. T h i r t e e n s m a l l , w e l l - d o c u m e n t e d samples of ancient plasters taken f r o m throughout the t o m b w e r e analyzed i n d e t a i l to d e t e r m i n e the c o m p o s i t i o n of the plaster material. S o m e results are s u m m a r i z e d i n T a b l e I. Analysis o f M a j o r E l e m e n t s . M a j o r elements w e r e d e t e r m i n e d quantitatively b y n e u t r o n activation analysis at the U n i v e r s i t y of T o r o n t o S L O W P O K E reactor. T h i s t e c h n i q u e was chosen because the available s a m p l e size was small. Differential scanning c a l o r i m e t r y w i t h a P e r k i n - E l m e r D S C - 1 B was u s e d to establish the plaster c o m p o s i t i o n f u r t h e r a n d to i n v e s tigate its t h e r m a l behavior. T h e analysis d i d not r e v e a l the d e h y d r a t i o n peaks that are e x p e c t e d i f g y p s u m ( C a S 0 · 2 H 0 ) w e r e present. A n a l y s i s w i t h a D i o n e x Q I C A n a l y z e r i o n chromatograph r e v e a l e d the presence of a significant a m o u n t of sulfate; therefore the plaster once d i d , i n d e e d , contain g y p s u m , w h i c h s u b s e q u e n t l y b e c a m e d e h y d r a t e d . T h i s finding confirms suggestions made i n p r e v i o u s studies (27-29). I o n chromatography of the plaster also r e v e a l e d a h i g h c h l o r i d e content, w h i c h is l i k e l y due to the presence of the s o d i u m c h l o r i d e mentioned previously. 4

2

C o m p a r i s o n with H o r e m h e b ' s T o m b . T h e results w e r e c o m p a r e d w i t h those o b t a i n e d from the analysis of the plaster of the royal t o m b of H o r e m h e b ( n u m b e r 57, V a l l e y of the K i n g s , T h e b e s , U p p e r E g y p t ) ( F i g u r e 4). T h e t o m b of H o r e m h e b , approximately 80 years o l d e r t h a n that of N e fertari, has b e e n r e c e n t l y restored a n d is n o w relatively w e l l p r e s e r v e d (36). It was excavated from l i m e s t o n e o f excellent q u a l i t y , a n d its o r i g i n a l plaster is strong a n d cohesive. A c o m p a r i s o n of the c h l o r i d e a n d sulfate contents of



42 ± 2 n= 3

9 0.03 9 0.005

0.029 ± 0.004 n= 3

0.17 ± 0.06 n= 9

n=9

n= 0.44 ± n= 0.121 ±

Ο.16 ± 0.08

6.3 ± 0.7 n= 3

28 ± 2 n= 3

NA

fl

32 ± 5 n= 3 NA

20.7 ± 0.8 n= 5

26.7 ± 0.8 η= 5 23 ± 2 n= 5 30 ± 2 n= 5 25 ± 2 n= 5

n

0.3 5 0.2 5 0.1 5 0.2 5

0.6 ± 0.1 —5

3.3 ± n= 0.7 ± n= 4.2 ± n= 2.5 ± n= 0.01 5 0.06 4 0.008 4 0.02 5

gypsum hemihydrate anhydrite (monoclinic) (hexagonal) (hexagonal) 4

2

4

4

CaS0 anhydrite (orthorhombic) 4

T h e first a n d last forms are the most stable forms (38); the two hexagonal forms are metastable. T h e transformation from m o n o c l i n i c g y p s u m to o r t h o r h o m b i c a n h y d r i t e involves a decrease i n specific v o l u m e of approximately 2 2 % , w h i c h contributes greatly to the p h y s i c a l w e a k e n i n g o f the p a i n t i n g substrate a n d the fragility o f the murals i n Nefertari's t o m b .

Effect of Climatic Conditions on Plaster Composition.

The tem-

perature a n d h u m i d i t y of a t o m b d e t e r m i n e w h e t h e r the g y p s u m f o r m o r the o r t h o r h o m b i c a n h y d r i t e f o r m is most t h e r m o d y n a m i c a l l y stable. A t 28 °C a n d 2 5 % R H , o r t h o r h o m b i c a n h y d r i t e is the stable f o r m i n the t o m b of N e f e r t a r i (38). E a r l y measurements of the t e m p e r a t u r e a n d h u m i d i t y i n six royal tombs i n the V a l l e y of the K i n g s indicate that the c l i m a t i c conditions i n a l l tombs i n s p e c t e d also favor the formation of o r t h o r h o m b i c a n h y d r i t e (45). A l t h o u g h H o r e m h e b ' s t o m b was not one o f those s t u d i e d , it was b u i l t at the same d e p t h , i n the same rock, a n d w i t h a p l a n similar to that of the t o m b of Seti I for w h i c h measurements of t e m p e r a t u r e a n d h u m i d i t y exist (20 °C a n d 4 0 % R H at the d o o r a n d 25 °C a n d 3 4 % R H at the far end) (45). T h e r e f o r e , on the basis of this evidence alone, w e expect that the c l i m a t i c conditions w i t h i n H o r e m h e b ' s t o m b also favor the formation of o r t h o r h o m b i c a n h y d r i t e from the o r i g i n a l plaster. O n the basis of o u r analyses, this reaction d i d not occur as c o m p l e t e l y as it d i d i n the t o m b of N e f e r t a r i (see p r e v i o u s section).


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Effect of Impurities on C a S 0 Transformation.


4

303

T h e transition

from g y p s u m to o r t h o r h o m b i c a n h y d r i t e is slow b u t occurs e v e n at a m b i e n t temperatures (44). T h e r e l a t i v e l y large concentration of finely d i v i d e d s o d i u m c h l o r i d e present i n the plaster i n the t o m b of N e f e r t a r i m a y have facilitated the d e h y d r a t i o n process. T h e presence of a hygroscopic m a t e r i a l , such as s o d i u m c h l o r i d e , can h e l p p r o m o t e d e h y d r a t i o n reactions. A l s o , i m p u r i t i e s w i t h i n the lattice of a crystalline structure can w e a k e n the lattice (46, 47) a n d t h e r e b y accelerate t h e r m o d y n a m i c a l l y favored reactions. T h e s e points suggest a strong correlation b e t w e e n the extent to w h i c h the d e h y d r a t i o n reaction proceeds a n d s o d i u m c h l o r i d e concentration, b u t t h e y do not exc l u d e the p o s s i b i l i t y that d e h y d r a t i o n can take place i n the absence of salt. A l t h o u g h the o r t h o r h o m b i c C a S 0 i n H o r e m h e b ' s t o m b (see p r e v i o u s section) m a y be present as an i m p u r i t y , it c o u l d also indicate that the plaster i n H o r e m h e b ' s t o m b is n o w i n its i n i t i a l stages of deterioration. O n the other h a n d , possibly the climate i n the t o m b of H o r e m h e b , p r i o r to its discovery, was cooler a n d m o r e h u m i d before it was discovered. T h e external climate of the V a l l e y of the Q u e e n s m a y have b e e n hotter a n d d r i e r t h a n that of the V a l l e y of the K i n g s . I n d e e d , the i n t e r a c t i o n of a l l these c l i m a t i c events m a y have c o n t r i b u t e d to the p r e f e r e n t i a l d e h y d r a t i o n of the t o m b of N e f e r t a r i . M o r e on-site h y d r o c l i m a t o l o g i c a l data from b o t h the V a l l e y of the Q u e e n s a n d the V a l l e y of the K i n g s are n o w n e e d e d . T h e E A O has i n f o r m e d us that some of these measurements are already i n progress. T h e plaster i n the t o m b of N e f e r t a r i may r e m a i n i n a t h e r m o d y n a m i c a l l y stable, desiccated state as l o n g as the conditions of t e m p e r a t u r e a n d h u m i d i t y i n w h i c h it n o w exists do not change. W e are n o w s t u d y i n g the effects of c h a n g i n g h u m i d i t y o n the ancient plaster materials t h r o u g h a series of s i m ulation e x p e r i m e n t s that i n v o l v e the use of synthetic plasters a n d c o n t r o l l e d h u m i d i t i e s . I n i t i a l results have s h o w n that s o d i u m c h l o r i d e plays a k e y role i n the water uptake process i n the t o m b (see L o n g - T e r m Studies of T e m perature a n d H u m i d i t y ) . 4

Reconstruction, Restoration, and Conservation Phnning Since 1904, m a i n t a i n i n g the c l i m a t i c status q u o i n the t o m b of N e f e r t a r i has p r o v e d difficult, as has b e e n d e s c r i b e d i n previous sections. I n a d d i t i o n to the h u m i d i f i c a t i o n processes o c c u r r i n g i n the t o m b , w e l l - m e a n i n g plaster repairs are a major source of a d d i t i o n a l water. T h r e a t e n e d m u r a l s have b e e n fortified p e r i o d i c a l l y w i t h n e w plasters, the most recent repairs h a v i n g b e e n made i n 1983. B y M a r c h 1984, the h u m i d i t y h a d increased considerably to an estimated 50 ± 1 0 % R H c o m p a r e d w i t h 31 ± 1% R H i n D e c e m b e r 1977 (28) a n d 16 ± 1% R H i n M a r c h 1981. I n the closed t o m b , increased h u m i d i t y alone cannot l e a d to r e h y d r a t i o n of the o r t h o r h o m b i c a n h y d r i t e , w h i c h is a t h e r m o d y n a m i c a l l y unfavored



304


reaction. N e v e r t h e l e s s , absorption a n d adsorption of water b y the o r i g i n a l plaster especially i n the presence of s o d i u m c h l o r i d e w i l l occur as a result of the increased h u m i d i t y o r the d i r e c t application of w e t plasters to the walls d u r i n g repairs. T h i s water intake m a y lead to localized r e h y d r a t i o n of the o r t h o r h o m b i c a n h y d r i t e w i t h subsequent s w e l l i n g i n the areas near the application of w e t plaster. T h e extent of this s w e l l i n g m a y be significant. It is a c o m p l e x function of the concentration of water brought into the t o m b as w e t plaster a n d the n o n u n i f o r m i t y of the s o d i u m c h l o r i d e concentration. T h e r e f o r e , there m a y b e insidious gradients i n plaster s w e l l i n g that may be difficult to detect. T h e m i g r a t i o n of moisture w i l l be accompanied b y the m i g r a t i o n of water-soluble salts, w h i c h m a y l e a d to h y d r a t i o n - r e h y d r a t i o n cycles over m u c h w i d e r areas. A l l these processes definitely w e a k e n this already fragile t o m b a n d w i l l lead to its further degradation. T h e r e f o r e , traditional methods m u s t clearly b e reevaluated i n the d e v e l o p m e n t of a conservation scheme for this site. Reconstruction and Restoration. E n o u g h i n f o r m a t i o n is available to indicate that the careful, far-sighted, scientific conservation of the t o m b of N e f e r t a r i w i l l b e at least as slow a n d painstaking as the conservation of other great m o n u m e n t s i n m a n y other parts of the w o r l d . T h i s situation is especially so because of the extreme fragility of the t o m b . V e r y careful w o r k m u s t be d o n e at this site because of the anticipated large influx of visitors. T h e construction of an exact r e p l i c a of the t o m b of N e f e r t a r i near the o r i g i n a l site m a y be an excellent alternative to fast a n d untested conservation efforts and s h o u l d seriously be c o n s i d e r e d . It is b o t h practical a n d possible to b u i l d an exact a n d subterranean r e p l i c a near the t o m b w i t h o u t a l t e r i n g the character of the V a l l e y of the Q u e e n s as a historic site. T h e careful construction of a r e p l i c a 100 m east of the entrance to the v a l l e y w i l l r e d u c e the i m p a c t of vibrations created b y any necessary preparatory excavation. A free-standing r e p l i c a of the t o m b is another alternative. I f such a r e p l i c a is designated as the first stop o n tours of the V a l l e y of the Q u e e n s , tourist bus traffic into the v a l l e y p r o p e r c o u l d be forestalled; the hazardous vibrations a n d exhaust p r o d u c e d b y these vehicles w o u l d b e r e m o v e d . A r e p l i c a of Nefertari's t o m b w i l l a l l o w m o r e visitors to see a faithful r e p r o d u c t i o n of this u n i q u e m o n u m e n t . T h e construction of a r e p l i c a w i l l not r e q u i r e further examination i n the t o m b . Surveys (23, 48) a n d several sets of photographs (23, 24, 30) of the t o m b are available, the most recent h a v i n g appeared i n press i n 1971 (23). T h e 1971 set of photographs is the o n l y p u b l i s h e d complete c o m p i l a t i o n i n color. Because the p h o t o g r a p h i n g of the t o m b i n 1971 was c o n c e r n e d w i t h d o c u m e n t i n g the geometry of the t o m b , the color r e p r o d u c t i o n i n these photographs is not sufficiently accurate to serve as a guide to color r e p l i c a t i o n . I n 1982, the E A O , i n collaboration w i t h the U n i t e d N a t i o n s E d u c a t i o n a l ,



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Scientific, a n d C u l t u r a l O r g a n i z a t i o n ( U N E S C O ) , rephotographed the t o m b , u s i n g the most m o d e r n techniques. T h i s series of photographs w i l l soon b e c o m e available. T h e techniques u s e d i n ancient E g y p t i a n paintings are also k n o w n (27, 36), a n d there are talented E g y p t i a n specialists w h o can recreate t h e m . T h e i m p o r t a n c e of this m o n u m e n t justifies such an approach; respected p r e c e dents exist, notably at Lascaux (8). B y taking this p a t h , conservation w o r k o n the o r i g i n a l t o m b can deal w i t h the stabilization of the m o n u m e n t a n d not w i t h d o c u m e n t a t i o n or the accommodation of i n t e r e s t e d visitors. Conservation Planning. The unique physicochemical, climatic, and geological conditions of the t o m b of N e f e r t a r i s h o u l d p r o v i d e the basis of any p r o p o s e d conservation scheme. T h e s e studies m u s t be c o n d u c t e d m e t i c u l o u s l y a n d w i l l necessarily be t i m e c o n s u m i n g . P r e d i c t i v e studies o n e v e r y aspect of this site m u s t p r e c e d e any conservation w o r k . A series of initial r e c o m m e n d a t i o n s (31, 34, 35) was s u b m i t t e d to the Ε A O i n this r e g a r d , and some of these r e c o m m e n d a t i o n s are discussed i n the f o l l o w i n g sections. M A I N T E N A N C E O F T E M P E R A T U R E AND HUMIDITY. A s a first step towards stabilization of the w h o l e t o m b , the identification, i m p r o v e m e n t , a n d m a i n tenance of its c l i m a t i c a l l y most stable c o n d i t i o n s h o u l d be u n d e r t a k e n . T h e excessive h a r m f u l h u m i d i t y m u s t be e l i m i n a t e d , a n d the t o m b s h o u l d be d e h u m i d i f i e d to at least its pre-1983 l e v e l (25% R H ) . T h e t e m p e r a t u r e a n d h u m i d i t y i n the closed t o m b must be m e a s u r e d continuously. T h e construction of an a i r - c o n d i t i o n i n g system is the most essential step of the conservation scheme, especially d u r i n g the i m p l e m e n t a t i o n of c o n servation treatments. A system that is r u g g e d , r e l i a b l e , a n d u n o b t r u s i v e can be custom designed. T h e system must have sufficient capacity to k e e p the t e m p e r a t u r e a n d h u m i d i t y stable w i t h i n the t o m b regardless of all external conditions a n d also be able to r e s p o n d q u i c k l y to changes caused b y e n t r y (49, 50). T h e a i r - c o n d i t i o n i n g system must have safeguard mechanisms against extreme fluctuations caused b y humans or natural events. I n d e e d , such a m e c h a n i s m may also serve as a means of c o n t r o l l i n g access to the t o m b , w h i c h w i l l be based o n the ability of the system to accommodate changes i n t e m p e r a t u r e a n d h u m i d i t y . A back-up system is also necessary i n the event of failure of the p r i m a r y system. F o r most of the year, the external h u m i d i t y is h i g h e r than that i n the u n v e n t i l a t e d t o m b ( F i g u r e 6). Therefore, the air s u p p l y to the t o m b m u s t be d e h u m i d i f i e d to an acceptable average value, a n d the t e m p e r a t u r e m u s t be automatically readjusted to m a t c h the o p t i m a l i n t e r n a l t e m p e r a t u r e . A c o o l e r - d e h u m i d i f i e r c o u p l e d w i t h a heater is a possible, b u t not necessarily the best, configuration, w h i c h w o u l d r e q u i r e 29,000 k j / h for d e h u m i d i f i cation a n d 22,000 k j / h for heating. T h e s e values are based o n two air changes p e r h o u r , w i t h air e n t e r i n g at 35 °C a n d 3 5 % R H a n d l e a v i n g at 28 °C a n d


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2 5 % R H . T h e v o l u m e o f the t o m b is approximately 4 5 0 m ; t w o changes o f treated a i r p e r h o u r w i l l r e m o v e t h e water vapor p r o d u c e d b y 60 p e o p l e i n 1 h a n d m a i n t a i n t h e C 0 p r o d u c e d b y 43 p e o p l e i n 1 h at 0 . 1 % v / v C 0 . T h e s e n u m b e r s are p r e s e n t e d as useful guidelines; t h e y are not m e a n t to i m p l y t h e r e c o m m e n d a t i o n o f u n r e s t r i c t e d access. 3

2

2

C O N T R O L O F C O A N D DUST. V e n t i l a t i o n of the t o m b m u s t b e m o d u l a t e d to ensure a constant a n d appropriate C 0 partial pressure. C h a n g e s i n C O concentrations i n t h e a i r m a y b e c r u c i a l to t h e survival o f the paint layer because the u n d e r l y i n g C a C 0 w h i t e w a s h layers are affected b y the presence of C 0 . A t t h e B e n i H a s a n tombs, M i d d l e E g y p t , C 0 is suspected to c o n t r i b u t e to d e t e r i o r a t i o n (17-21). W e are p e r f o r m i n g a study o f this m e c h a n i s m o f paint layer a n d p i g m e n t deterioration i n N e f e r t a r i s t o m b . a


2

s

3

2

2

P a r t i c l e size analysis o f airborne dust is also necessary i n t h e c o n s i d eration o f appropriate a i r - c l e a n i n g devices for use i n a c o m p l e t e a i r - c o n d i t i o n i n g system at this site. A l l components o f this a i r - c o n d i t i o n i n g system must b e i n s t a l l e d so that the a r c h i t e c t u r a l a n d artistic character o f the t o m b is not d i s r u p t e d o r e n d a n g e r e d i n any way. T h e construction o f a d o u b l e - d o o r c l i m a t i c seal, that i s , a n entrance foyer w i t h a d o o r b e t w e e n i t a n d t h e outside a n d a second door b e t w e e n the t o m b a n d t h e foyer, s h o u l d b e c o n s i d e r e d (35). T h i s seal w i l l p r e v e n t the d i r e c t exposure o f t h e t o m b to t h e e n v i r o n m e n t . W h e n t h e c l i m a t i c conditions are stable, essential w o r k w i t h i n t h e t o m b , p r e c e d e d b y careful testing, c a n b e c o n s i d e r e d . T h e first step w i l l b e dust r e m o v a l . T h e influx o f dust a n d other desert debris is a natural consequence o f increased access to t h e t o m b . F u r t h e r m o r e , t h e t o m b floor is a reservoir o f dust. W e have e x a m i n e d t h e role o f dust i n t h e d e t e r i o r a t i o n o f m u r a l surfaces (17-21). A f t e r t h e r e m o v a l o f dust, a dust-free, p r e f o r m e d c e m e n t , o r better still, granite floor s h o u l d b e installed. Parts o f the tombs i n w h i c h paintings are already i r r e t r i e v a b l y lost m u s t b e c o v e r e d w i t h p o l i s h e d granite slabs to p r e v e n t dust generation from these obvious dust sources. S t r u c t u r a l consolidation, c l e a n i n g of paint layers, and p r o t e c t i o n c a n t h e n follow. S T R U C T U R A L CONSOLIDATION. Structural consolidation o f t h e plaster layer is necessary for p r o t e c t i o n against m e c h a n i c a l stresses, i n c l u d i n g seism i c activity a n d vibrations generated b y buses that b r i n g visitors to t h e V a l l e y o f the Q u e e n s . T h e use o f injectable p o l y m e r s is a viable solution. T h e most stable p o l y m e r s m u s t b e u s e d , a n d i t may b e necessary to c u s t o m design p o l y m e r s for this purpose. T h e i n t e g r i t y o f the plaster layer, before, d u r i n g , a n d after treatment m u s t b e d e t e r m i n e d a n d m o n i t o r e d b y u l t r a sonic, p i e z o e l e c t r i c , o r photoacoustic methods. T h i s p r o c e d u r e a n d t h e use of p o l y m e r s for paint layer p r o t e c t i o n w i l l r e q u i r e extensive c o n t r o l l e d exp e r i m e n t a t i o n , especially o n t h e p h y s i c o c h e m i c a l nature o f the various p i g -


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ments u s e d i n the t o m b . C u r r e n t k n o w l e d g e of ancient p i g m e n t c o m p o s i t i o n and c h e m i s t r y m u s t be e x t e n d e d to i n c l u d e the interaction of the p i g m e n t s w i t h the total e n v i r o n m e n t of the t o m b of N e f e r t a r i . Areas of discoloration are k n o w n i n this t o m b , some of w h i c h w e r e caused b y p r e v i o u s conservation experiments (27). T h e p o l y m e r s u s e d must protect murals from m o i s t u r e , m u s t b e totally i n e r t , a n d m u s t not alter the appearance of the p a i n t layer or cause s t r u c t u r a l changes w i t h i n it. P r o p e r v e n t i l a t i o n r e q u i r e m e n t s for p o l y m e r use d u r i n g conservation m u s t also b e considered. W h e n n e w a n d b e t t e r techniques b e c o m e available, it m u s t be possible to r e m o v e these p o l y m e r s a n d the p o l y m e r s u s e d i n the s t r u c t u r a l consolidation of the plasters w i t h m i n i m a l or no damage to the t o m b , i n the t r a d i t i o n of r e v e r s i b l e conservation treatments. A r e v i s i o n of the l i g h t i n g practices i n this t o m b , for example the use of readily available, sharp-cut-off U V filters, m u s t be u n d e r t a k e n to exclude possible photodegradation of p i g m e n t s . A t present, a system of fluorescent lights i l l u m i n a t e s the walls from the base of each m u r a l . T h i s system is adequate n o w because of its i n f r e q u e n t use. H o w e v e r , the situation w i l l b e different i f increased visitation is a l l o w e d . W e are s t u d y i n g a l l these aspects of the conservation scheme w i t h existing, w e l l - d o c u m e n t e d samples taken f r o m this t o m b a n d other nearby tombs. T h e wholesale r e m o v a l of salts s h o u l d not b e c o n s i d e r e d at this t i m e . T h e salts are essentially a s t r u c t u r a l c o m p o n e n t i n t h e i r o w n right. T h e isolation of the t o m b f r o m the influx of water a n d h u m i d i t y w i l l arrest the m o v e m e n t of these salts. DRAINAGE. L i k e m a n y of its neighbors, the t o m b of N e f e r t a r i is threate n e d b y increasingly frequent t o r r e n t i a l d o w n p o u r s . A canopy o n top of the site w i t h appropriate drainage s h o u l d b e constructed to d i v e r t this source of w a t e r (34). A l t h o u g h historically, degradation of t o m b e n v i r o n m e n t s m a y have b e e n i n f l u e n c e d b y g r o u n d w a t e r flow, this is not the case w i t h the V a l l e y of the Q u e e n s or w i t h most of the tombs of the V a l l e y of the K i n g s . T h e s e sites w e r e specifically chosen for t o m b construction because of t h e i r e x t r e m e l y stable a n d d r y e n v i r o n m e n t s . A l t h o u g h i r r i g a t i o n i n the N i l e V a l l e y has increased m o r e r e c e n t l y , the V a l l e y of the Q u e e n s is still situated approximately 2 k m f r o m i r r i g a t e d fields. T h e r e f o r e , direct a n d u p w a r d water flow i n the limestone rock is not l i k e l y to affect the t o m b of N e f e r t a r i because the w a t e r table m u s t be considerably b e l o w the l o w e r levels of the t o m b . H o w e v e r , the flow of w a t e r t h r o u g h the s u r r o u n d i n g rock s h o u l d b e evaluated b y appropriate geological studies, as w e l l as b y c o m p u t e r s i m u l a t i o n . A t r e n c h system a r o u n d the t o m b may be c o n s i d e r e d as a means of isolating the walls f r o m any i n c o m i n g water. C o n solidation of the plasters m u s t p r e c e d e this step, a n d the construction of these trenches m u s t b e done w i t h o u t causing vibrations i n the t o m b .



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REVIEW O F CONSERVATION E F F O R T S . C o n s e r v a t i o n efforts are often c o n d u c t e d b y i n d i v i d u a l s a n d groups w h o do not release details of t h e i r w o r k e v e n w h e n p r o t e c t i o n of f o r t h c o m i n g patents is not i n v o l v e d . S u c h confi dentiality is unnecessary a n d is, i n d e e d , suspect (51). T h i s u n w a r r a n t e d secrecy m u s t not accompany the conservation efforts for such a national treasure as the t o m b of N e f e r t a r i . Therefore, p u b l i c a t i o n of d e t a i l e d c o n servation w o r k i n r e s p e c t e d p e e r - r e v i e w e d journals is mandatory. N o t o n l y w i l l this w e l l - a c c e p t e d scientific practice result i n m o r e responsible conser vation w o r k , b u t it w i l l ensure i n t e r n a t i o n a l d e l i b e r a t i o n , w h i c h can l e a d o n l y to a m o r e rigorous study a n d evaluation of o p t i m u m solutions to c o n servation p r o b l e m s .

Conclusions T h e ongoing macroarchaeometric study of the t o m b of N e f e r t a r i allows us to examine the u n i q u e c h e m i s t r y o c c u r r i n g i n the archaeological materials used i n its c o n s t r u c t i o n . W e h o p e that this w o r k w i l l also c o n t r i b u t e to the art h i s t o r y of the t o m b a n d to a m o r e d e t a i l e d u n d e r s t a n d i n g of the t e c h nology u s e d b y its b u i l d e r 3250 years ago. T h i s w o r k p r o v i d e s an example of a general approach to some m o d e r n conservation p r o b l e m s . A s a corollary, it demonstrates the a b i l i t y of large archaeological structures to act as sensitive probes of e n v i r o n m e n t a l change.

Acknowledgments T h i s chapter is based o n the progress r e p o r t s u b m i t t e d to the E g y p t i a n A n t i q u i t i e s O r g a n i z a t i o n , C a i r o , January 1987. W e acknowledge the E g y p tian A n t i q u i t i e s O r g a n i z a t i o n for p r o v i d i n g p e r m i t s to w o r k i n the t o m b o f Nefertari. W e are grateful to H i s h m a t M e s s i h a w h o first suggested the study of this t o m b to us. O u r interest i n the project was considerably e n h a n c e d b y discussions w i t h the late Z a k i Iskander. W e are grateful to A l i e l K h o u l i , D i r e c t o r of E x c a v a t i o n s , E g y p t , whose absolute a n d contagious d e d i c a t i o n to the cause of the p r e s e r v a t i o n of E g y p t i a n antiquities e n s u r e d o u r c o n t i n uous interest i n this project. T h e F r a n c o - E g y p t i a n C e n t r e for the Studies of the T e m p l e s of K a r n a k , as part of t h e i r collaborative agreement w i t h the U n i v e r s i t y of T o r o n t o , p r o v i d e d us w i t h the c l i m a t i c data f r o m the N i l e V a l l e y . R. G . V. H a n c o c k of the U n i v e r s i t y of Toronto S L O W P O K E reactor p r o v i d e d t e c h n i c a l advice a n d assistance i n the n e u t r o n activation analyses. Κ. M . W i l s o n - Y a n g acknowledges the receipt of a g r a n t - i n - a i d f r o m S i g m a X i . T h i s research was sponsored b y the U n i v e r s i t y of T o r o n t o , the N a t u r a l Sciences a n d E n g i n e e r i n g Research C o u n c i l of C a n a d a , a n d the C a n a d i a n C o m m i s s i o n of U N E S C O / C I D A Assistance P r o g r a m m e .


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References


1. Billard, T. C.; Burns, G.; Wilson-Yang, K. M. Presented at the X X I t h Inter national Conference on Archaeometry, Brookhaven National Laboratories, Stoney Brook, NY, May 1981. 2. El-Kammar, Α.; Hancock, R. G . V.; Allen, R. O. In Chapter 18 of this book. 3. Jakes, Κ. Α.; Angel, A . In Chapter 26 of this book. 4. Sales, K. D . ; Oduwole, A . D.; Convert, J.; Robins, G . V. Archaeometry 1987, 29, 103-109. 5. Sales, K. D.; Robins, G . V.; Oduwole, D . In Chapter 19 of this book. 6. Bada, J . L . ISR Interdisc. Sci. Rev. 1982, 7, 30-46. 7. Bada, J . L.; Gillespie, R.; Gowlett, J . A . J.; Hedges, R. Ε. M . Nature (London) 1984, 312, 442-444. 8. Vouvé, J.; Brunet, J.; Vidal, P.; Marsal, J . Stud. Conserv. 1983, 28, 107-116. 9. Quindos, L . S.; Bonet, Α.; Diaz-Caneja, N.; Fernandez, I.; Gutierrez, J . R. Atmos. Environ. 1987, 21, 551-560. 10. Billard, T. C.; Burns, G. "On Deterioration of Egyptian Antiquities, Causes and Remedies"; progress report to the Egyptian Antiquities Organization; University of Toronto: Toronto, Canada, 1979. 11. Billard, T. C.; Burns, G. Nature (London) 1980, 285, 654-655. 12. Billard, T. C.; Burns, G.; Wilson-Yang, Κ. M . "Salinization of the Nile Valley: The Kanak Area"; report to the Egyptian Antiquities Organization; University of Toronto: Toronto, Canada, 1981. 13. Billard, T. C.; Burns, G.; Wilson-Yang, Κ. M . J. Am. Res. Cent. Egypt 1982, 19, 115-117. 14. Burns, G.; Wilson-Yang, Κ. M. "Degradation in Egyptian Black Granite"; report to the Egyptian Antiquities Organization; University of Toronto: Toronto, C a n ada, 1982. 15. McFarlane, J.; Wilson-Yang, Κ. M.; Joseph, S.; Frey, C.; Burns, G . Can. J. Chem. 1983, 61, 718-723. 16. Wilson-Yang, Κ. M.; McFarlane, J.; Burns, G . J. Soc. Stud. Egypt. Antiq. Assoc. 1985, 15, 52-54. 17. Burns, G.; Wilson-Yang, Κ. M. "The Great Tombs at Beni Hasan and Their Conservation"; preliminary report to the Egyptian Antiquities Organization; University of Toronto: Toronto, Canada, 1981. 18. Wilson-Yang, K. M.; Burns, G . J. Am. Res. Cent. Egypt 1982, 19, 119-121. 19. Burns, G.; Wilson-Yang, Κ. M. "Chemistry of the Deteriorating Murals in the Beni Hasan Tombs"; progress report to the Egyptian Antiquities Organization; University of Toronto: Toronto, Canada, 1984. 20. Burns, G.; Wilson-Yang, Κ. M. "The X-ray Photoelectron Spectroscopy of the Ancient Murals in the Tombs at Beni Hasan, Egypt"; progress report to the Egyptian Antiquities Organization; University of Toronto: Toronto, Canada, 1987. 21. Wilson-Yang, Κ. M.; Burns, G . Can. J. Chem. 1987, 65, 1058-1064. 22. Smith, S. E . J. Field Archaeol. 1986, 13, 503-510. 23. Goedicke, H.; Thausing, G . Nofretari; Akademische Druck u. Verlagsanstalt: Graz, Austria, 1971. 24. Schiaparelli E . Relazione sui Lavori della Missione Archaeologica Italiana in Egitto (1903-1922); 1922; Vol. 1, pp 51-104. 25. Baikie, J . Egyptian Antiquities in the Nile Valley; Methuen: London, 1932; pp 517-521. 26. Capart, J . Thèbes; Vromant et Cie: Brussels, 1925; p 153.


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27. Iskander, Z. In Recent Advances in Science and Technology of Materials; Bishay, Α., E d . ; Plenum: New York, 1974; Vol. 3; p 1. 28. Wilson-Yang, K. M.; Billard, T. C.; Burns, G . J. Soc. Stud. Egypt. Antiq. 1982, 12, 9-11. 29. Plenderlith, H. J.; Mora, P.; Torraca, G . ; de Guichen, G . "Conservation Prob lems in Egypt"; U N E S C O consultant report, Contract 33.591, 1970. 30. Stoppelere, A . Ann. Serv. Antiq. Egypt 1942, 40, 941-950. 31. Burns, G.; Wilson-Yang, Κ. M. "The Tomb of Nefertari, Valley of the Queens its Conservation Problems"; preliminary report to the Egyptian Antiquities Organization; University of Toronto: Toronto, Canada, 1981. 32. Curtis, G.; Rutherford, J. Soil Mech. Found. Div. Am. Soc. Civ. Eng. 1981, 3, 71-74. 33. Strabo; cited in Heizer, R. F.; Stross, F.; Hester, T. R.; Albee, Α.; Perlman, I.; Asaro, F.; Bowman, H . Science 1973, 182, 1219-1224. 34. Burns, G.; Wilson-Yang, Κ. M. "The Internal Climate of the Tomb of Nefertari"; progress report to the Egyptian Antiquities Organization: University of Toronto: Toronto, Canada, 1982. 35. Burns, G . ; Wilson-Yang, Κ. M. "The Continuous Measurement of Temperature Humidity in the Tomb of Nefertari"; progress report to the Egyptian A n tiquities Organization; University of Toronto: Toronto, Canada, 1984. 36. Hornung, E. Das Grab des Haremhab im Tal der Königen; Francke Verlag: Berne, 1971. 37. Lucas, Α.; Harris, J . R. Ancient Egyptian Materials and Industries, 4th ed.; Harris and Arnold: London, 1962; p 78. 38. Blount, C. W.; Dickson, F. W. Am. Mineral. 1973, 58, 323-331. 39. Posnjak, E . Am. J. Sci. 1938, 35A, 247-272. 40. Zen, E . - A . J. Petrol. 1965, 6, 124-164. 41. Hardie, L . A . Am. Mineral. 1967, 52, 171-200. 42. Cody, R. D.; H u l l , A . B. Geology 1980, 8, 505-509. 43. Kinsman, D. J. J. N. Ohio Geol. Soc 2nd Proc. Symp. on Salt 1966, 1, 302-326. 44. Ridge, M. J.; Beretka, J . Rev. Pure, Appl. Chem. 1969, 19, 17-44. 45. Lucas, A . Ann. Serv. Antiq. Egypt 1924, 24, 12-14. 46. Kittel, C. Introduction to Solid State Physics, 5th ed.; Wiley: Toronto, 1976. 47. Hannay, Ν. B. Solid State Chemistry; Prentice-Hall: Toronto, 1967; Chapter 8. 48. Weeks, K. Newslett. Am. Res. Cent. Egypt 1981, Winter. 49. Croome-Gale, D . J.; Roberts, Β. M. Airconditioning and Ventilation in Build ings; Pergamon: Toronto, 1975. 50. McQuiston, F. C. Heating, Ventilation and Air-conditioning, 2nd ed.; Wiley: Toronto, 1982. 51. Dutton, D . Nature (London) 1987, 327, 10. RECEIVED for review Tune 11, 1987. ACCEPTED revised manuscript February 10, 1988.


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