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Treatments of organic objects to extract ferrous compounds from waterlogged archaeological wood are well documented. For several years, numerous laboratories have been seeking to determine suitable conservation treatments for such organic objects. For chemical treatments, complexing agents such as EDTA and DTPA, along with acids such as citric and oxalic acids, were selected. In addition, oxidants and reducing agents were tested as pre-treatments to improve extraction rates. In fact, chemicals produce a selective reaction on ferrous compounds, which may improve or be inhibited by complexation or dissolution reactions. Their action depends on the type of compound to be extracted and those present inside the wood. The objective of this study was to make a comparative assessment of the various chemical conservation treatments identified and complement the evaluation of their extraction efficiency with a study of their impact on organic matter by adding criteria such as their visual aspect (using a spectrocolorimeter) and physicochemical actions by means of infrared spectroscopy and micromorphological observations. The effectiveness of EDTA was confirmed, as was that of citric acid, despite some questions arising concerning the presence of wood fibers in the treatment solution, even after rinsing. On the other hand, the extraction rate of oxalic acid, which has a very acidic pH, was unsurprisingly lower, but its visual and anatomical results raised the possibility of using it over a short period of time in view of the effectiveness observed on the wood surface. Pre-treatments improved extraction rates, except in the case of EDTA, which independently had a high extraction rate. It was observed that pre-treatments did not appear to cause any significant chemical degradation of the organic matter. This study provides a tool to assist conservators in selecting a chemical treatment that is in line with the state of decay of the wood, the characteristics of the ferrous compounds to be extracted, and the conservation objectives. [ABSTRACT FROM AUTHOR]

Highlights • The wooden foundations of Ponte di Rialto were analysed in order to determine the tree species used for its construction and to examine the timber's present-day physical and mechanical properties. • The foundations underwent micro-morphological, physical, chemical and mechanical analyses. • The footings of the bridge's foundations, mostly consisting of alder wood, were shown to be in a good condition generally. • Two periods of construction were determined. The later dating corresponds to the construction of the stone bridge that still exists today, while the other period probably refers to the foundations of the initial Ponte della Moneta. Abstract The wooden foundations of Ponte di Rialto (Rialto Bridge), the oldest and most famous of the four bridges spanning the Grand Canal in Venice, Italy, were analysed in order to determine the tree species used to construct the foundation, to examine the timber's present-day physical and mechanical properties and to identify construction periods. The material recovered during geotechnical surveys underwent micro-morphological, physical, chemical and mechanical analyses. The radiocarbon method was used for dating purposes. The footings of the bridge's foundations, mostly consisting of alder wood, were shown to be in good overall condition generally. A comparison of normal and polarised light images of wooden cross-sections showed abundant crystalline cellulose within the cell walls, indicating that the state of conservation of the waterlogged samples is very close to that of sound alder wood. Only one alder sample showed signs of severe bacterial attack, mostly concentrated in the fibre cell walls. Radiocarbon dating identified two distinct construction periods. One sample dates to 1570 AD ± 85, whilst another dates to the year 960 AD ± 59. The later dating corresponds to the construction of the stone bridge that still exists today. The earlier period, around the year 1000, likely refers to the foundations of the first bridge, built after several pontoon bridges, and corresponding to the initial Ponte della Moneta. [ABSTRACT FROM AUTHOR]

Foundation piles are a noteworthy example of waterlogged wood still constituting load bearing structures. Micromorphological analysis, investigation of physical properties (water content, residual basic density), compressive tests in wet conditions and chemical analyses (lignin, holocellulose) were carried out on samples taken in Venice. Obtained results demonstrated that both mass and strength were lost due to decay, but the residual strength loss was greater than the residual mass. It is also shown that this occurrence was due to the holocellulose decrease. Present results point out that basic density and holocellulose amount could be used as possible predictors of woodpiles residual strength. [ABSTRACT FROM AUTHOR]

The present paper deals with wood from Venice historic centre foundation elements. Samples were taken from both piles and planking (horizontal elements positioned above the pile heads), in 5 out of 6 districts of Venice. Considering the watery milieu, the diagnostic methodology for waterlogged archaeological wood was adopted, performing anatomical, chemical and physical characterisations. Our results show that the wood used for Venetian foundation elements belong to a small group of 5–6 species (alder, larch, oak, pine, elm and spruce, although the latter was probably of more recent introduction). Most of the analysed samples evidenced decay, which in some cases was high (residual basic densities of only 32%, and values of the ratio holocellulose to lignin as low as 0.3). It was evidenced how the state of preservation of wood was related to several factors, including: thickness of the element, depth of burial, horizontal/vertical position, and wood species. It was also shown how ash content does not reflect the state of preservation of waterlogged material, as it is sometimes reported in the literature. The diffuse decay was apparently not related to the general stability of the buildings under study. [ABSTRACT FROM AUTHOR]

The paper presents the results of the restoration and conservation work which has been carried out in three archaeological areas in the Autonomous Province of Trento. The areas, which have been opened to the public for more than ten years, are the open-air archaeological site of Monte S. Martino, Roman Tridentum (an underground site under the historical city centre of Trento), and Fiavé (a pile dwelling site in a peat bog). These areas present very different environmental characteristics and have therefore required different interventions according to their specific situation. In order to reduce maintenance and extraordinary costs, appropriate conservation of the archaeological remains is required. This consists of methodologies of conservation according to the characteristics of the environment; continuous monitoring systems and indirect preventive intervention; and annual maintenance planning. [ABSTRACT FROM AUTHOR]

Thermogravimetry (TG) is used to measure the change of sample mass versus temperature or time under a program controlling temperature. It is a common thermal analysis tool with a precise built-in balance, and accurate data can be obtained through a small amount of sample at the level of milligrams. The feasibility of the TG method for determining maximum water content (MWC) measurement of waterlogged archaeological wood was studied. Simulated waterlogged wood and waterlogged archaeological wood were used to determine the test condition for the TG method. MWC data obtained through the oven-dry and TG methods with different mass gradients from 0–10 mg to >50 mg were analyzed statistically. Deviation, error bar, and coefficient of variation were evaluated. According to the results, when sample mass is no less than 30 mg, and holding time at 105°C is no less than 40 min, data deviation between these two methods is less than 5%. Effect of sampling depth and presence of inorganic deposits were also investigated. Specimens were taken from an archaeological wood with a sampling depth from 2 to 6 mm, then MWC was measured through the TG method. The results indicate MWC of the samples taken from a depth of 2–4 mm is higher than that taken from a depth of 0–2 mm and is lower than that taken from a depth of 4–6 mm, which is related to inorganic deposits. The presence of deposits was verified through SEM-EDX. MWC of three archaeological wood samples from China and five archaeological wood samples from Italy were measured to verify the effectiveness of the TG method when wood species and degradation degree are different. [ABSTRACT FROM AUTHOR]

Huaguangjiao І is a Chinese ancient wooden shipwreck of South Song Dyansty (1127–1279 AD). Wood samples from Huaguangjiao І were analyzed in order to evaluate the preservation state of the waterlogged wood. Samples were studied from the anatomical, physical and chemical point of view. Thin slides of cross and longitudinal sections from samples were observed by optical microscope, micromorphological decay was classified into class 3 or class 4 according to the anatomical characters. Water content and basic density were measured. Maximum water content (MWC) of the wood samples is between 300% and 600%, residual basic density is about 50%. The proportion of the α-cellulose decreased to 25% of the normal value, and the content of the ash increased greatly. These results indicate the degradation of the wood is very high. In addition, there is a plenty of inorganic deposit in the wood structure. The inorganic compounds deposited in wood samples were analyzed by XRD and ICP qualitatively and quantitatively. The morphology and composition of the inorganic deposit was characterized through SEM-EDS, the majority were iron sulfide, including pyrite and marcasite (FeS 2 ), and fluorite (CaF 2 ). [ABSTRACT FROM AUTHOR]