Since pre-historic times people have known have to make a material that we know as leather. In Egypt, vegetable tanned leather was used since the pre-historic period, but the use of parchment dates back to the Middle Kingdom(1). We may consider that since 1884, with the work of Augustus Schultz, thec hrome tanning process began(2). There are a large number of important parchment manuscripts and tanned leathers (vegetable and chrome tanned leather) in archaeological sites (museums, storages, old libraries and excavation areas). From the moment of its creation, parchment or leather starts to age. Ageing as such is a process resulting from damage brought about as a consequence of production technology, environmental conditions, handling and repair(3). Degradation by heat is probably one of the major factors in the deterioration of a large portion of parchment and leather in museum collections(4). There is no doubt that the first stage of any conservation process should always be a detailed study of the condition of the leather with an understanding of the deterioration process in order to present some solutions for the conservation treatment. Most leather artifacts and parchment manuscripts in Egypt usually suffer because of unsuitable environmental conditions(5). A widly used parameter for measuring the condition of parchment and leather is the shrinkage temperature, representing the temperature of which leather has to be heated in an aqueous environment in order to lose its characteristic tridimensional fibre network construction. The loss of this structure causes the leather or parchment to shrink(6).
Reed, R., Ancients skins, Parchments and leathers, Seminar Press, London,        1972, p. 48. Thomson, R. S., Leather manufacture in the post medieval period withspecial references to Northamptonshire, Post Medieval Arch., London,         1981, p.161. Larsen, R., Micro methods for the analysis of parchment – MAP –   preliminary report, in care and conservation of manuscripts 5, Fellows –      JENSEN, Gillian and Springborg, the Royal Library, 2000, pp. 28-37. Williams, R.S., Surface encrustation on caribon skin coat, Canadian       Conservation Institute, Ottawa, Canada, 1982, pp.1-14. Abdel-Maksoud, G. and Marcinkowska, E., Changes in some properties of      aged and historical parchment, Restaurator, Vol. 21, Munich, 2000, p.138.     Larsen, R. Experiments and observation in the study of environmental  impact on historical vegetable tanned leathers, Thermochimica Acta, 2000,        p.365.