With aging, many rocks surfaces not in direct contact with the soil, develop a black coating. This deposit has been given different names: desert varnish [1,2], rock varnish [3], and biogenic rock varnish [4]. The rock varnish is a dark coating, usually 10 to 30 micrometers thick, with a variation from a few micrometers to over 500 micrometers [5]. It is composed of manganese and iron oxides, silica, and clay minerals. A similar type of coating is accreted in pottery found in ancient tombs [6].

Earlier studies demonstrated quantitatively that recent salinization of the Karnak Temples, Egypt, is due to evaporation of saline groundwaters under the temples. Furthermore, it was determined that the high salinity of groundwaters is due to extensive evaporotranspiration over the adjacent irrigated fields. To abate salinization, in 1986, a desalinization station was installed in the central part of Karnak at Lake Amun. Present studies indicate that by 1987, the desalinization effort was already very successful, with the salinity of the Lake being lowered by a factor of more than 37. Some residual salinity was still evident a year after desalinization stations were installed. It appears that this residual salinity is due primarily to leaching of salts which were deposited around the Lake before 1986. Thus, not only the Lake, but also the area adjacent to it appear to be desalinized as a result of construction of the desalinization station.

The hydric properties of three types of building stone used in certain Spanish monuments of outstanding historical-artistic value have been determined. The stones selected were dolomite, limestone and sandstone used in the cathedrals of Leon (northern Spain), Seville (southern Spain) and Salamanca (central Spain) respectively.

In the work described in this paper, different rock properties related to water were measured (absorption of water and water vapour, evaporation, capillarity and permeability to water vapour). Swelling characteristics of the sandstone were also determined.

The close correlation between the values of the parameters obtained for each property analyzed and the mineralogical-textural features of the rock, notably the porosity and form of the pore system, has been also demonstrated. In these stones, it has been observed that water absorption capacity is linked both to the volume of empty communicating spaces (open porosity) and to the presence and percentage of clay minerals.

In mercury porosimetry of limestone two hystereses are generated. A PV-- diagram for initial intrusion and extrusion reveals one hysteresis as entrapment of mercury in large cavities that are connected to the exterior through narrow channels. The other hysteresis is a loop (HL) enclosed between the extrusion and reintrusion curves which indicate narrow channels. An HL is unique to a stone.

The thermodynamic work (W) calculated as ΣPV, is W1, WE, WRE, WHy, and WT for the initial intrusion, extrusion, reintrusion, the hysteresis loop, and the entrapment, respectively. The pore-potential (U) defined as

regulates the volume and rate of movement of water through the pores which in turn determines the stone's durability. Microporous stones are highly susceptible to weathering and have a large value for WHy. WHy. in association with the WT can be related to the durability factor (DF) as

The DF values, thus obtained, accurately reflect the observed condition of the strata of the Sphinx.

The direct application of epoxy resins to deteriorating stone often encounters problems of penetration and color formation. Conservation scientists have worked around these problems by using organic solvents as carriers and have successfully consolidated stone with epoxy resins in a large number of projects. Work in Poland, Czechoslovakia, Italy and the United States is described. In Europe the methodology has evolved to treat objects of moderate size and isolated parts of buildings while in the United States procedures have been developed for stabilizing large portions of major buildings.

The aim of the present work is to compare the protective effect of solvent and water dispersed products on marble, Lecce and Istria stones. This choice is justified by the need of products effective also from the ecological and toxicological point of view. To obtain these informations two tests have been chosen: contact angle and water absorption. The contact angle may, in theory, be considered a measure of the water repellency, since complete wetting implies a contact angle of 0° and absolutely no wetting an angle of 180°. This does not apply to the water absorption by capillarity test because the absorption variation may be caused by either the water repellency action of the treatments or by the pore filling. However this test may give practical information about the general effect of the treatments. Moreover, the effect of treatments on permeability was investigated by vapour permeability test. Protective effect was studied after application of the products and at various stages of artificial weathering.

Different decay mechanisms, according to the exposure to rain actions, have been identified on a series of Istria stone samples derived from the Venetian buildings. Enquiries have been carried out on these samples by means of porosity measurements and chemical analysis in depth. In order to identify the decay mechanisms and their.kinetics, simulation tests have been,performed on exposed samples of Istria stone for a period of 19 months. These specimens have been analysed by several techniques in order to verify the chemical dissolution of limestone provoked by the rain action. The initial chemical attack on the exposed samples has been pointed out by XPS and RBS micro-analytical techniques.

Cleaning treatments necessary for stone conservation consist of removing compounds that were superimposed on the original material by means of physico-chemical processes.,The purpose of this work is to identify the transformation of stone surface by the LASER treatment. Cleaning test on Istria stone with LASER radiation at different energies and in different regimes have been performed. The depletion of the original material has been evaluated by means of SEM microprobe analyses.

Gels prepared from solutions of B72 acrylic resin and methyltrimethoxysilane (MTMOS) are examined by SEM. Four initial mixtures - 0,2,5 and 10% w/v B72/MTMOS - produced gels whose fractured surfaces exhibit distinct features. Scanning electron microscopy shows that neat MTMOS produces a glass-like gel while the addition of B72 creates MTMOS-derived spheres in a “connective tissue” of acrylic resin. These particle sphere/acrylic resin solids are mechanically weak composites.

New generations of polymer-ceramic nanocomposites are being developed by intercalation of layered solids. Synthetic approaches include intercalative polymerization, direct polymer intercalation and molecular dispersion of the host layers in the polymer matrix. The unique physical and mechanical properties of the hybrids are attributed to the molecular dispersion and the synergism between the individual components.

The Australasian Antarctic Expedition base at Commonwealth Bay (67°S 142°E), also known as ‘Mawson's Huts’ include some of the earliest buildings in Antarctica. The prefabricated timber buildings of Oregon beams and Baltic Pine (Pinus sylvestris) claddings were erected in January 1912 and were occupied for two years: they are thus approximately contemporary with the better known Scott and Shackleton huts near McMurdo Base in the Ross Sea.

The expedition was led by Dr Douglas Mawson, later Professor Sir Douglas Mawson, and its inspiration was scientific rather than a race to the South Pole. The buildings and artefacts remaining on the headland, also called Cape Denison, reflect considerable scientific achievement in geology, upper atmosphere physics, surveying, meteorology and biology and the site constitutes an important monument in the early exploration of this remote and inhospitable continent.

While the huts are of recent date, the rapid rate of deterioration due to the extreme climate means there is some urgency to developing a method of preserving the building. The timbers have been seriously worn, or ‘corraded’ by snow particles carried in the katabatic winds. These winds can exceed 300km per hour, sometimes for days. The isolation of the site, accessible by sea for only three months of the year adds to the logistical difficulties. There has been considerable public debate in Australia about which method of preservation is appropriate.

The author, a materials conservator and industrial chemist, visited the site in December 1985 and has been studying the problems of the site as a postgraduate student for the past year.

Recent research on the technical aspects of the architectural reliefs at the site of Chan Chan, Peru, has yielded new evidence with which to assess conflicting relative sequences for the monumental compounds of the imperial city.

Over 108 samples of mural paintings from Teotihuacán, México, were studied by scanning electron microscopy, optical microscopy and X-ray diffractometry. The results show a sequence in the techniques employed to produce the mural painting's supporting plasters -made of lime and different sands. The technical stages found can be used as archaeological data to help understand the continuous evolution of 800-year mural paintings. The consequences of our study are discussed in detail.

Mortars collected from the Cheops pyramid, the Sphinx and the Chephren pyramid, all at Giza, Egypt, have been compared with recently found mortars of a cult building of the aceramic neolithic at Nevali üori (south east of Urfa, province Hilvan, Turkey), probably one of the earliest sites of civilization. As methods of investigation thermal analysis, X-ray diffraction as well as analytical scanning and transmission electron microscopy have been used. The egyptian mortars have been found to be primarily made up of gypsum, anhydrite and calcite. The comparative results with mortar of the recently detected temple site at Nevali Con, Turkey, give evidence that the burning or otherwise chemical treatment of limestone as crucial ingredient for the fabrication of mortar has been performed at a very early period (10'000 - 8000 B.C.). In order to further confirm the described findings 14C dating measurements have been carried out. The results of the described studies raise many questions concerning early civilizations and their knowledge of technologies as well as the transfer mechanisms of this knowledge.

An understanding of corrosion processes is beneficial in the preservation of ancient ceramic artifacts. A wealth of information is available on this topic in the materials science and engineering literature. Significant contributions to the corrosion literature have been made over the last 15 years due to the extensive research performed on nuclear wasteform systems. This paper will review the current state of understanding of aqueous corrosion of glasses. We will discuss how this information can be applied to some of the current issues in preservation of archaeological ceramics.

At 15 prominent churches and cathedrals in 7 European countries the environmental corrosive stresses at the stained glass windows were assessed by glass sensors. Special emphasis was given to the protective properties of different types of protective glazings. The obtained total stress level data, based on MI-glass sensor measurements, help to conclude on the appropriate choice of the ventilation systems and give information about specific environmental impacts. The results indicate that internally ventilated protective glazings have a higher protective effect than externally ventilated systems. The nonventilated type of protective glazing even raised the corrosive stresses for the stained glass windows.

A comparative study on the effects of restorational cleaning methods for stained glass windows was carried out using corrosion sensitive model glasses. Typical deterioration phenomena like crusting, leaching and microcracking could be simulated using accelerated weathering in climatic test cabinets. The sensibilization of such samples caused by cleaning was assessed by infrared spectroscopy and light microscopy after re-weathering.

The copper sulfate minerals chalcanthite (CuSO4.5H20), antlerite (Cu3SO4(OH)4), and brochantite (Cu4SO4(OH)6) are observed as corrosion products on copper alloy objects such as statues which are exposed to weathering. The usual product in aqueous corrosion is brochantite, though posnjakite (Cu4SO4(OH)6H20) is also known. No copper sulfate mineral is commonly found in artifacts recovered from near-surface burial. These observations can be explained in terms of stability diagrams and microbiological activity.

Thermochemical data are used to construct a modified log-activity diagram for the system Cu-H-O-Cl-(C02) at standard temperature and pressure(STP). In these diagrams, coordinate axes represent activities of aqueous copper species and chloride ions other thermodynamic variables are collapsed onto the diagram. Modified log-activity diagrams are used as a supplement to study Pourbaix diagrams for the equilibria relevant to bronze disease and copper pitting and to show the relation between them.

Corrosion of artifacts from atmospheric trace gases occur continuously. A new polymeric system which provides atmospheric trace gas corrosion protection has been developed. These polymers are called Reactive Polymers. The polymers consist of a blend of polymer resin (eg. polyethylene, polypropylene, ABS, PVC) with stable solid-state additives. These polymers can be formed into bags, tubing, sheets, bubble-pack, trays, etc. Corrosion protection is provided for artifacts from ancient periods, such as chinese mirrors, and the Freer Chinese Bronzes, to fine silver items from Colonial times in the USA. This protection from corrosion or tarnish by atmospheric H2S, COS, and HCl is provided for extended periods of time.