Physicochemistry of the Tomb of Nefertari, Egypt.

Abstract

The Tomb of Nefertari, no. 66, Valley of the Queens, is an internationally known monument of historic and artistic importance; it is considere d one of the most beautiful of the Royal Egyptian tombs. The fragility of its plaster along with its ubiquitous sodium chloride crystals and microcrystals have complicated its conservation and restoration. In order to determine the optimum pathway for its conservation, the physicochemical processes which occur now in this Tomb must be well understood. To improve this understanding, samples of plaster taken from the Tomb have been analyzed using Differential Scanning Calorimetry and X-ray Diffraction and have been shown to be fully dehydrated; previous findings suggest that this is not the case in all contemporary Royal tombs. Although we are not aware of any kinetic study of gypsum dehydration in the solid state, the presence of anhydrite in the Tomb of Nefertari suggests that the CaSO4 ·2H2O → CaSO4 + 2H2O reaction is catalyzed. It is reasoned that finely-dispersed sodium chloride crystals act as effective catalysts in this reaction.

Archaeometry at Slowpoke‐toronto

“…On some occasions, INAA was employed to confirm the relative homogeneities of samples used in TL dating (Pavlish and Beukens 1978; Sheppard et al 1982; Pavlish and Sheppard 1983). At other times, INAA was used to try to establish geological sources of materials (Julig et al 1987, 1988, 1989, 1991a, 1992; Smeaton and Burns 1988; Burns et al 1989; Hancock et al 1989c; Jarvis 1990, 2000; White et al 1991; Best et al 1992; Hancock and Fox 1992; Sheppard 1992; Long et al 2002). INAA has been used in provenance studies (Wainwright and Down 1986; Julig et al 1991b, 2002; Volterra and Hancock 1994; Volterra et al 2000; Hancock 2003a).…”

The Stability of the Tomb of Nefertari 1904-1987

“…For most of its history the tomb existed in a desiccated state and, primarily because of this stable, dry climate, all of its gypsum-based plasters gradually lost their waters of crystallization [1,11]. As a consequence, the plasters also lost their binding properties [1,11].…”

“…As a consequence, the plasters also lost their binding properties [1,11]. This has resulted in yet another serious instability in the tomb and is the fifth cause of its deterioration.…”

“…The dissolution, movement and recrystallization of sodium chloride is a consequence of the movement of water through the plaster and painted surfaces. The loss of chemically bound waters in the painting substrate appears to be accelerated by the sodium chloride dispersed throughout the gypsum-based plaster [1,11]. Furthermore, the adsorption and desorption of air moisture, which occurs as humidity fluctuates, causes solution and reprecipitation of surface-deposited sodium chloride.…”

“…The plaster layer, which in some places is as thick as 5cm, forms the substrate on which the murals were carved, coated with a thin white wall preparation [9] and 154 Studies in Conservation 34 (1989) 153-170 then painted. The calcium sulphate dihydrate component of the plaster, which is its binding agent, has completely dehydrated to anhydrous calcium sulphate [1,6,9,11] and the plaster as a whole contains significant amounts of sodium chloride dispersed at the submicroscopic level, as found through a series of sensitive chemical analyses [1,11]. Furthermore, the plaster substrate is riddled with sodium chloride crystals [1,6,[12][13][14][15], from the microscopic to several cubic centimetres in volume, and sodium chloride efflorescence products appear on the painted surfaces.…”