古代饱水木材脱水定型机理探讨

从木材干缩的一般理论出发,探讨了古代饱水木材脱水变形的主要影响因素。阐述了古代饱水木材与新鲜木材的区别,提出饱水木材发生形变的主要影响因素同现代木材一样,是由于氢键缔合的结合水挥发,从而引起干缩和开裂。要保持脱水后的定型一方面要加固细胞壁外壁,更重要的从细胞壁内壁进行加固。     

Selected physical parameters to characterize the state of preservation of waterlogged archaeological wood: a practical guide for their determination

Non-destructive and destructive methods for determining the physical parameters of waterlogged wood such as the porosity, the water content, the wet and dry bulk densities plus the density of the cell wall material are presented. Considerations in respect to determination of masses, volumes and sampling size are discussed.     

云南剑川海门口遗址饱水古木降解的微观构造分析

文中采用扫描电镜(SEM)和透射电镜(TEM)对海门口遗址饱水古木进行降解机理分析。结果表明:古木细胞次生壁收缩严重并与胞间层分离;胞间层保存较完好,呈连续网状。说明古木纤维素和半纤维素降解相对严重,木质素降解相对较轻。古木主要是受细菌降解,通过SEM和TEM均可见明显的细菌腐朽特征。细菌首先侵入细胞腔,再通过S3层侵入细胞壁内部。细胞壁内由于降解而产生的空隙在几十到几百纳米之间。饱水古木也受到了一定程度的真菌降解,但这类真菌主要降解古木内淀粉等物质,对细胞壁物质降解能力差,主要是使古木变色。     

EVALUATION OF THE APPLICABILITY OF CONVENTIONAL METHODS FOR THE CHEMICAL CHARACTERIZATION OF WATERLOGGED ARCHAEOLOGICAL WOOD

A series of 112 waterlogged archaeological wood samples of different provenances, wood species, burial times and states of preservation were analysed with the aim of assessing the validity (in terms of limits and reliability) of procedures conventionally used in the pulp and paper industry, to evaluate the state of preservation of decayed wood. In particular, the extent of any damage wrought on decayed wood tissue by the repetitive cycles that characterize these procedures was evaluated as a function of the degradation of the samples. The results indicated that standard methodologies give reliable measurements regardless of the extent of wood decay. However, it is essential to compare these data with those of non‐decayed wood that has been measured using the same procedures to take account of the errors that are inherent in these methodologies and that affect measurements.     

泗水国出土泡桐材性研究

木质文物出土后环境发生了很大的变化,如不对其进行科学的保护处理就会发生快速的腐朽变化。在选择保护处理方法前对木材的材性进行科学的分析可以为保护方法的确定提供科学的依据。本工作从木材成分、含水率、干缩性、出土泡桐与新鲜泡桐干缩率比较、干燥过程中的电镜分析几个方面对泗水国汉墓出土的泡桐进行了材性研究。结果表明,泗阳汉墓出土的泡桐纤维素和半纤维素的含量比新鲜泡桐的含量下降很多,但木质素的相对含量却增加了,说明泗阳汉墓出土的泡桐在埋藏环境中可能更多地是受到褐腐菌的侵蚀。含水率的高低是反映木材腐蚀度一个重要指标,泗阳汉墓出土的泡桐平均含水率高达1211%,从弦向、径向、横切面的平均收缩率数值来看,出土的泗水国泡桐文物收缩变形很严重,从电子显微镜图片观察,细胞结构各向干缩特性与新鲜木材完全不同。由此可见,不能用常规木材的干缩特征和木材的变化规律来指导泗水国出土泡桐的研究和保护工作,在选择保护处理方法时要结合木材本身的现状选择适合的材料和工艺。     

Shape recovery of collapsed archaeological wood ware with active alkali-urea treatment

Most wooden remains from archaeological sites in waterlogged burial environments are found to be intact without shrinkage despite centuries of storage. However, waterlogged wooden remains are subject to shrinkage damage and some even lose up to 80% of their original volume when exposed to air. The shrinkage of archaeological waterlogged wood with the loss of a large part of the initial volume of the wooden remains has been considered irreversible. Here we show that “active alkali-urea”, serving as a re-swelling chemical agent, can almost fully restore the collapsed archaeological wood to its original shape. The restoration experiment showed that the main reason for the restoration of collapsed wood is that the collapsed cell cavity almost completely recovered its original shape during active alkali-urea treatment. We suggest that the shape of collapsed archaeological wood remains can be fully recovered, and that the collapsed archaeological wood can thereby recover its valuable cultural properties.     

Preservation,storage and display of waterlogged wood and wrecks in an aquarium: “Project Aquarius”

A test aquarium containing water and waterlogged historical wooden material was observed during a three-year period at Vänernmuseum, Sweden, to test the feasibility of preserving and exhibiting archaeological wood or shipwrecks in a way accessible to the public. Experiments were also set up in a laboratory environment, to provide information on single factors that could influence the long-term preservation state of wood, and other processes that may occur in the water.     

木材在PEG法处理过程中收缩原因的研究

论述了PEG法处理木质文物过程中造成木材收缩的原因。讨论了木材含水率、浸泡温度、PEG分子量以及其浓度变化梯度等因素与木材收缩的关系。还介绍了弥补PEG法不足的一些简单方法。     

天然树脂加固淹埋木质文物

为了对剑川海门口遗址出土的古思茅松进行实验性加固保护,对古思茅松进行草酸脱色、甲醇溶剂脱水,然后使用松香和虫胶的甲醇溶液作为加固剂进行渗透、干燥等加固工序。加固后的样品表面色泽浅淡,保持了木材原有的色泽、纹理和质感。基本密度达到0.437g/cm3,已接近现代木材的基本密度。顺纹抗压强度较加固前增加了24.58%。绝干状态时测得的各向全干收缩率分别为:纵向2.22%、径向3.54%、弦向7.73%,均在正常木材干缩变化范围之内。扫描电子显微镜(SEM)研究表明:天然树脂附着在细胞壁表面,对细胞壁起到了足够的支撑作用,加固后的木材细胞壁切面平整、致密、轮廓清晰,胞壁间界面结合好,细胞腔较光滑。研究表明,本加固方法能有效降低木质文物的吸湿性、提高其各项物理力学性质。当木质文物需做其它处理时只需用甲醇或乙醇将松香和虫胶溶出即可,加固过程可逆,这解决了木质文物将来的再处理问题。     

Physical and mechanical properties of waterlogged wood treated with hydrolyzed feather keratin

The physical and mechanical properties of waterlogged wood treated using avian feather were investigated. Avian feather is mainly composed of keratin protein and expectable materials for industrial utilization. The feather hydrolysate enhanced the mechanical properties of waterlogged wood and recovered the correlations between modulus of rupture (MOR) and modulus of elasticity (MOE) and anisotropy. The color of the wood treated with hydrolyzed feather solution exhibited natural wood texture. The feather hydrolysate had antimicrobial activity. However, the wood treated with hydrolyzed feather solution showed high hygroscopicity.     

饱水古木材难溶盐分析

为研究饱水古木材中难溶盐的成分和分布,基于电感耦合等离子体光谱、X射线衍射以及显微共聚焦激光拉曼等分析手段对出土出水饱水古木材表面和纵向横向不同取样深度的元素含量和分布、表面凝结物以及纵向横向切面颗粒物的物相进行了分析。分析结果表明饱水古木材含有大量的Fe、S和Ca元素,包含这三种元素的凝结物主要由难溶盐和不溶物组成。难溶盐主要分为两大类,一类为钙盐(包括硫酸盐、碳酸盐和磷酸盐等),一类为硫铁化合物(包括硫铁矿、黄铁矿、磁黄铁矿等);不溶物包括各类铁氧化物(如针铁矿、纤铁矿、赤铁矿和水合氧化铁)以及硫单质等。难溶盐分析结果有助于有针对性地对饱水古木材难溶盐尤其是对古木材危害比较大难溶盐进行预防控制和有效脱除。     

CONSTRUCTING CARIBBEAN CHRONOLOGIES: COMPARATIVE RADIOCARBON DATING OF SHELL AND WOOD ARTEFACTS FROM PRE‐COLUMBIAN SITES IN CUBA

The lack of robust chronological frameworks for pre‐Columbian archaeology in the Caribbean limits the interpretive potential of ongoing studies of inter‐site and inter‐island interaction. This paper reviews the dating of 28 wood and shell artefacts from sites in northern Cuba in an attempt to date pre‐Columbian activity in the region and develop dating methodologies for the study of pre‐Columbian interaction in the Caribbean. This research compares dates from wood and shell artefacts from the waterlogged site of Los Buchillones in north‐central Cuba with dates from shell artefacts from sites on eight islands in the Sabana–Camaguey archipelago in the Bahama Channel. In addition to providing a chronological framework based on absolute dates for pre‐Columbian activity in northern Cuba, this paper also considers the methodological issues of using shell for dating pre‐Columbian activity in the Caribbean.     

DESSICATION AND DESTRUCTION: THE IMMEDIATE EFFECTS OF DE-WATERING AT ETTON, CAMBRIDGESHIRE

This paper presents the first results of a long-term project to monitor changes in ground water conditions in parts of the East Anglian Fenland. So far the project has been concerned with two sites immediately north of Peterborough, at Borough Fen and Etton. The Borough Fen data are still being assessed, but Etton has provided results which warrant prompt publication.
The water levels were monitored in a series of boreholes across the Etton Neolithic enclosure for a period of two years (1982–4), to study the effects of the variation in the local groundwater table on the waterlogged contents of the enclosure ditch.
The first part of the paper (CF) assesses the results of this programme. The ambient water table remained at or above the level of the primary and lower secondary deposits in the ditch, thus accounting for the excellent preservation of botanical remains. Within one month of the adjacent quarry pumps being turned on the water table had fallen by up to one metre below the lowest archaeological deposits, and has not recovered since, to the almost immediate detriment of the botanical record.
The second part of the paper (MT) discusses the observed variation in the preservation of wood in particular, and describes the effects of de-watering on the deposits of wood in the enclosure ditch.     

DETERIORATION ASSESSMENT OF WATERLOGGED ARCHAEOLOGICAL LIGNOCELLULOSIC MATERIAL VIA 13C CP/MAS NMR*

This study investigates the residual chemical composition of waterlogged archaeological lignocellulosic material found in Greece. Hazelnut pericarps and oak wood found in a 16th‐century wreck, along with endocarps of olives dated at 300 bc , were examined. ¹³C CP/MAS NMR was applied to compare fresh and waterlogged archaeological materials. Results show qualitative alterations in their composition. The virtual absence of peaks at ~21 ppm and ~173 ppm, corresponding to hemicelluloses in all archaeological materials, indicates that these constituents can be an important indicator in assessing the type and degree of deterioration.     

Reasoned use of chemical parameters for the diagnostic evaluation of the state of preservation of waterlogged archaeological wood

Waterlogged archaeological wood undergoes decay processes that depend on both the burial conditions and the constituting species, and which cause the depletion of the structural components of wood cells. To quantitatively assess the state of preservation of the decayed material, specific parameters are usually measured by means of both chemical and physical analyses. In this paper an innovative approach in the use of the data obtained from these kinds of measurements is developed. A series of 132 archaeological wood samples of different wood species, burial times and states of preservation, and coming from different sites in Italy, was analysed. Their residual chemical composition, maximum water content and basic density were measured, and a reasoned use of these parameters was carried out through their elaboration, with the aim of both evaluating eventual incongruence or anomalies in the raw physical and chemical data (which has never been accomplished so far) and directly comparing in a reliable way the analytical results obtained from archaeological samples with very different states of preservation. This approach allowed defining the effective values of chemical parameters related to wood decay according to a same reference basis of calculation among the various data. By this way, it was possible to state that lignin can be also attacked by the agents causing biotic decay, and that in hardwoods its decay is more related to the burial conditions than to the wood species. Instead, the mechanism of polysaccharide depletion is diversified: conifers showed a uniform behaviour whereas hardwoods were more species-dependent. Moreover, in addition to the chemical composition, also anatomical factors influence the carbohydrate rate of decay in waterlogged wood.     

Kauramin法加固饱水古木件的机理

利用FT IR、DSC以及形态组织观察等方法,初步探讨了Kauramin(MF树脂)法渗透加固16世纪饱水古船残块(古像木)的过程与机理。结果表明,MF树脂可填充在橡木细胞组织的各层中,与其中的纤维素、木质素等形成大量氢键,高度交联,最终形成网络状整体,从而使古木件的机械性能得以改善。     

Laboratory Experiments as Support for Development of In Situ Conservation Methods

Abstract

Within the EU-Project BACPOLES (EVK4-CT-2001-00043) bacterial wood degradation could be simulated in laboratory experiments to investigate the living conditions of the up to now unknown bacteria consortia, named erosion bacteria (EB), which cause considerable decay on waterlogged archaeological wood. In these Microcosm (MC) experiments the role of oxygen and chemical composition of the sediment were investigated. Therefore, the microcosms were subjected to different gassing treatments and the free dissolved oxygen was measured in different depths of the microcosms by special oxygen sensors (optodes). In further experiments the chemical composition of the sediment was verified to investigate the influence of different nutrient concentrations to the degradation process by EB.

From the findings it can be concluded that bacterial wood decay can proceed without free oxygen present but that it is more intense if oxygen is available. A water flow like streams in the sea, simulated by vertical water circulation, seems to stimulate the degradation activity and the degradation of wood by EB seems to be a result of low nutrient levels in the surrounding area.     

一种新型水溶性单体聚合-冷冻干燥联用法在饱水木质文物脱水定型应用中的研究

为了改善饱水木质文物脱水定型技术保护的定型效果、操作周期以及环保经济性,本研究以田螺山遗址、河姆渡遗址和茅山遗址出土的3种饱水木材试样为实验对象,进行了以水溶性单体丙烯酰胺(AM)和N-乙烯基吡咯烷酮(NVP)为反应物的单体聚合-冷冻干燥联用法的研究。首先在水体系中选取不同比例的AM和NVP在水溶液中聚合,并根据聚合和冷冻前后的体积变化率控制在±5%以内的标准进行聚合体系的筛选。然后选取其中5组符合条件的聚合体系对3种饱水木材进行脱水定型处理,当在聚合体系中AM和NVP的质量分数总和不高于7.5%时,经单体聚合-冷冻干燥联用法处理后的试样的尺寸变化率可控制在±5%以内,达到良好的脱水定型的效果。     

THE CHARACTERIZATION OF WATERLOGGED ARCHAEOLOGICAL WOOD: THE THREE ROMAN SHIPS FOUND IN NAPLES (ITALY)*

Three apparently well‐preserved shipwrecks dating back to Roman times were brought to light near Piazza Municipio in Naples (Italy), during the excavation for the construction of Line 1 of the subway. The shipwrecks were covered by marine sand and silt, below the water table. In order to establish the nature and the extent of wood degradation and, therefore, determine how best to preserve the shipwrecks, a diagnostic investigation was carried out. The study involved the identification of wood species, chemical characterization of the residue component and physical and micro‐morphological characterization.     

To be and to continue being a cog: the conservation of the Bremen Cog of 1380

The conservation project for the Bremen Cog of 1380 took 38 years from salvage to presentation of the ship to the public in the Deutsches Schiffahrtsmuseum in 2000. The ship was salvaged from the River Weser in about 2000 pieces, and stored in water tanks. A new museum was built, and the Cog reassembled from the waterlogged timbers. The ship was reconstructed with most of the weight being taken by the ceiling of the hall via a steel-rod hanging system. Then a conservation tank was built around the hull, and a novel two-step PEG-treatment applied, especially developed for the Cog. In two consecutive baths PEG 200 and PEG 3000 stabilized lesser degraded and heavily degraded wood against shrinkage, splitting, and warping. After cleaning, the wood looks dark brown, dry, and natural. The extraordinary project is regarded a success.