赤藓糖醇在考古木材保护中的应用

选取3种不同遗址出土(出水)的考古木材为试验样品,以赤藓糖醇为定形加固材料,在50℃恒温水浴中以不同质量分数的赤藓糖醇溶液对试验样品进行渗透填充,渗透填充结束后采用真空冷冻干燥方式对试验样品进行脱水干燥。分别从尺寸稳定性、环境稳定性、力学性能、显微形貌几个方面考察了赤藓糖醇对考古木材的定形保护效果。试验结果显示赤藓糖醇作为定形加固材料能够对考古木材起到良好的定形保护作用,定形保护效果随赤藓糖醇质量分数的增加而提升,质量分数为30%赤藓糖醇即可显著提升考古木材的尺寸稳定性、环境稳定性和力学性能。赤藓糖醇以晶体形式在考古木材细胞壁上析出,对木材组织起到支撑和加固作用,提高了考古木材的尺寸稳定性和环境稳定性。     

湖州康山明墓出土明器的保护预研究

湖州康山明墓出土了53件木质家具明器。这些出土明器颜色深黑,部分器物表面附着一层厚厚的黄白色硬结物。通过XRD物相分析和ICP元素分析,黄白色硬结物的主要成分为CaCO_3,器物本体木材基质内Ca元素和Fe元素的含量也较高。本研究选取4件小木碟进行定形保护的预研究,其中3件木碟在40℃水浴中用30mmol/L的复合脱盐脱色剂(Ryt)进行脱盐脱色处理,然后分别采用乙醇—乙醚—松香/乳香胶法、乙醇—高级醇法、聚乙二醇(PEG)4000—真空冷冻干燥法进行定形处理,对照试样为去离子水—真空冷冻干燥法。研究结果表明:Ryt脱盐脱色与乙醇—乙醚—松香/乳香胶法联用处理的明器具有最好的保护效果。该保护工艺适合于康山明墓出土明器的科学保护。     

海洋出水南宋古沉船饱水木构件的定形保护

华光礁Ⅰ号南宋古沉船遗址打捞出水饱水木构件的定形保护工作包括木构件的材性分析、盐分分析与可溶盐脱除、聚乙二醇(PEG)2000渗透填充与真空冷冻干燥脱水等内容。材性分析结果表明木构件属于松属木材,绝对含水率和化学成分含量分析结果标明木构件降解严重。盐分分析与可溶盐脱除实验表明,木构件内部含有大量的可溶盐以及难溶和微溶的无机盐,采用去离子水浸渍方式可以脱除渗透入木构件内部的绝大部分可溶盐。与自然干燥引起的试样严重收缩开裂相比,用PEG2000为定形加固剂结合真空冷冻干燥的方式可以对木构件起到良好的定形保护效果。定形保护后的木构件尺寸稳定性大大增强,木质纹理清晰自然,木构件表面的附着物以及附着物中凝嵌的残瓷片和残存的海虫躯壳也清晰可见。     

PEG稳定河姆渡遗址出土香樟的干燥特性研究

研究饱水古木材的干燥特性可以对古木材的定型保护提供重要的参考,因此本研究以河姆渡遗址出土的香樟木材为试样,在加热的条件下,用不同质量百分比浓度的聚乙二醇(PEG 2000)为定形加固剂,研究了降解饱水香樟在自然条件下的干燥特性。结果表明降解饱水香樟的自然干燥过程可以分为干燥初期试样质量的快速下降和干燥后期试样质量平稳变化两个阶段。干燥初期试样质量下降比与干燥时间符合m/m0=-kt+c的干燥方程且线性良好。随着PEG处理浓度的升高,两个阶段之间逐渐出现一个过渡过程,PEG处理浓度越高,过渡过程越明显。达到干燥终点时,香樟试样的尺寸稳定性随着PEG浓度的升高而显著增强,当浓度达到70%时,纵向、径向和弦向的收缩率下降明显,但弦向的收缩率仍相对较大。随着PEG处理浓度的增加,自然干燥后的香樟试样表观色泽逐渐加深。因此,PEG 2000浓度以不超过40%为宜。     

魏家庄遗址出土铁质文物的脱盐处理研究

山东济南魏家庄遗址出土铁质文物中含有大量有害氯离子,严重威胁着文物的安全。因此,脱盐就成为该批铁器保护的重点,是阻止铁器继续腐蚀的重要保证。在经一系列实验工作后,该批铁器的脱盐溶液采用0.005mol/L NaOH溶液,对于仅为铁质的容器类铁器采用直接浸泡法,同时结合冷热交替和超声波法;对于带有鞘的兵器类铁器采用2%Primal AC33加固后再进行脱盐;对于带有漆皮痕迹的铁器也试用了纸浆脱盐法。铁器经脱盐后氯离子含量大大降低,脱盐取得了很好的效果。     

秦俑二号坑出土一件彩绘跪射俑的保护修复

本研究针对秦俑二号坑出土的一件彩绘跪射俑进行了保护修复,是在考古出土现场保存状况、文物病害及病害机理科学分析的基础上进行的现场保护与实验室保护修复。现场保护重在稳定文物状态和应急处理;实验室保护则依据文物保护程序进行保护修复,在进行文物表面清理工作后,使用AC33(丙烯酸乳液)及PEG200(聚乙二醇)加固彩绘层,使用环氧树脂对陶俑进行了粘接修复,收到了良好的效果。此彩绘陶俑的保护修复工作可为以后大型彩绘文物的保护修复提供参考和借鉴。     

西汉初期粉彩陶俑的保护研究

为了探索研究出土脆弱粉彩陶俑的保护方法,采用偏光显微粉末法(PS-PLM)对11种颜色颜料进行了分析鉴定。用X一射线衍射对文物表面土壤溶盐的成分及含量进行了测试,测得干土含盐量高达2.5%。先用WO-WO2型有机硅对粉彩进行预加固,再用8%Na2[Na4(Po3)6]溶液多层纸张贴敷法对粉彩俑进行了脱盐处理,然后进行保色,拼对粘接,再加固和表面保护,保护后的粉彩俑色彩鲜艳,无炫光,触摸弹击粉彩不掉色,保持了器物的原貌。达到理想的保护效果。     

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。     

无地仗层彩绘保护技术研究

为克服古建筑木构件上无地仗层彩绘保护的两个技术难点;彩绘加固,以防颜料脱落;防止彩绘表面易发黑,影响彩绘的色泽。本工作以常熟彩衣堂彩绘保护实例,采用先封堵木材中的纤维孔隙,再用改进的B-72配方(在配方中,加入了紫外线吸收剂,木材中油溶性成分固定剂PM-1,抗静电剂,防污剂SL等)进行化学加固处理,较好地克服了上述技术难点,为古建筑木构件上无地仗层彩绘的保护探索出了一条新途径。     

太仓万丰村半泾河古船船材主要离子的测试研究

为做好太仓万丰村半泾河古船的脱盐保护工作,本研究检测了半泾河古船的第6、7隔舱板和第8隔舱龙骨及船板下淤泥样品中主要元素和离子的含量,并用电导率仪测量样品在脱盐过程中电导率的变化情况。检测结果表明,木材和淤泥中的主要元素含量高于对照样品,且主要以可溶性盐的状态存在;木材腐蚀程度也与其离子含量有关,腐蚀程度愈严重,样品的离子含量也愈大;经过脱盐处理后,脱盐溶液的电导率值降低至较低水平。测试数据将对今后古船脱盐工作有一定的指导意义。     

Investigating the processes necessary for satisfactory freeze-drying of waterlogged archaeological wood

Preliminary studies into methods for improving and safeguarding the preservation of waterlogged archaeological wooden artefacts are presented. Mannitol, sorbitol and trehalose have been tested as replacements for polyethylene glycol (PEG) as a treatment prior to freeze-drying of wooden archaeological objects. The highest anti-shrink efficiency achieved in this short experiment was (70 ± 15) % using a 20% weight per volume solution of sorbitol after soaking for one week. The collapse or eutectic temperature of each solution used was determined using a freeze-drying microscope. Importantly, it was noted that the collapse temperature of the solutions was reduced by several degrees after use for treatment of the wood samples for one month. A freeze-drying microscope with a cold light source has been used to observe the real-time freeze-drying behaviour of various treatments inside a thin section of wood, confirming that this novel technique is indeed possible and useful. Lastly, the effects of magnesium phytate as an iron chelator have been studied. It was found that the treatment lowers the collapse temperature of a PEG 600/2000 solution by roughly 3 °C meaning that objects must be freeze-dried at a correspondingly lower temperature. Iron K-edge X-ray absorption near-edge spectroscopy analysis showed that the treatment extracted approximately half of the iron(III) ions present in the timbers.     

Study of interactions between polyethylene glycol and archaeological wood components by C high-resolution solid-state CP-MAS NMR

While use of polyethylene glycols, PEG, polymers for archaeological wood conservation has been well established, there is almost no study of such composite materials with carbon thirteen high-resolution solid-sate NMR. We demonstrate that NMR is an useful analytical tool to characterize rapidly samples of conserved wooden objects. By choosing an appropriate value of the contact time (from 3 to 5 ms) for which the PEG component gives only a small residual NMR signal in the CP-MAS experiment, it is possible to edit selectively the spectra of the wood components. It allows one to visualize the degradation extent of the archaeological wood even when the conservation processes have been already applied. Moreover, by studying the kinetics of CP-MAS experiments, the time constants, T_1ρH and T_CH values for PEG moiety were computed. From these data, it is shown that either in the crude commercial product or in incorporated in archaeological woods, two components are present and they are the signatures of crystalline (or ordered) and amorphous (or disordered) molecular domains. Moreover, it was shown in the archaeological woods that almost 30% of PEG was in close molecular interactions with lignins. This study is the first evidence that the PEG in conserved wood can interact at a molecular level with wood components. It also demonstrates that the PEG diffuses inside the residual cell walls of archaeological wood. This data are important for scientists in charge of process development for the conservation of wooden artifacts.     

Modeling wood acquisition strategies from archaeological charcoal remains

Archaeological charcoal remains are often used to reconstruct local woodland composition in the past, but rarely address how and why people may have selected specific woody taxa for particular purposes. Models from the field of human behavioral ecology predict that people forage for wood resources by taking into account the relative usefulness, abundance, and handling time related to procuring different wood types. Archaeological and ecological data from the site of Gordion, in Central Anatolia (modern Turkey), were used to test expectations associated with such models. Results suggest that inhabitants of Gordion used wood types for fuel in proportion to their local availability, but that they selected specific, more distant woods for construction. In most occupation periods pine was preferred for construction, perhaps because it produces long, straight timbers for roofing, despite the distance at which it grows from the site. This case study demonstrates that behavioral ecology modeling can help to distinguish between multiple wood acquisition strategies potentially used in the past and improve our understanding of wood use from archaeological charcoal remains.     

Investigations on pre-treatment prior to freeze-drying of archaeological pine wood with abnormal shrinkage anisotropy

The current research is aimed at determining the nature of changes in the dimensions and hygroscopicity of archaeological Scots pine (Pinus sylvestris L.) wood after treatment with polyethylene glycols and vacuum freeze-drying. The research was undertaken on mature sapwood with narrow annual rings and a small percentage of latewood. The experimental material used in a comparative assessment is characterised by a considerable degree of wood degradation, but low tangential and radial shrinkage and relatively high longitudinal shrinkage. The waterlogged samples were treated with aqueous solutions of PEG 300 with final concentrations: 8, 12, 16 and 20% (v/v), to which PEG 4000 with final concentration: 15, 20 and 25% (w/v) was added. After freeze-drying and seasoning of samples in the air at RH 30, 40, 50 and 65%, the water content of the samples and the degree of shrinkage of wood in three anatomical directions were determined. The dimensional stability of the samples was also determined on the basis of ASE values at RH 50%.     

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.     

A Spanish Man‐o‐War in New Zealand? The 1864 wreck of Grafton and its lessons for pre‐Cook shipwreck claims

This paper considers the 1864 wreck of Grafton in the Auckland Islands, and its implications for wreck analysis and pre‐Cook exploration claims. The captain of Grafton, Thomas Musgrave, stated that the schooner was built from the wreck of a Spanish man‐o‐war, and archaeological analysis of the wreck found that the timbers are a tropical South American species, and had possibly been reused. The implications of this are clear; it is possible that timbers that originated in pre‐Cook (1769) ships lie in New Zealand, but without a full understanding of the historical and archaeological context of any such timbers, including their reuse in later ships, it is not possible to claim proof of pre‐Cook European exploration of New Zealand.     

New data on relevant ancient Egyptian wooden artifacts: Identification of wooden species and study of the state of conservation with multidisciplinary analyses

Wood species identification and characterization of its weathering processes are crucial steps in the scientific approach of conservation of wooden cultural heritage. Many precious wooden objects of ancient Egypt are largely present in museums, nevertheless relatively little information is available concerning the nature of timber used and on their status of conservation. To address this gap, the wooden species of three relevant archaeological wood objects (statue, box, and coffin) arising from different Egyptian archaeological sites dated from the Old Kingdom (2,686–2,181 BC) to New Kingdom (1,550–1,069 BC) were deeply studied. Five hardwood and softwood species were identified belonging to Tamarix mannifera, T. gennessarensis, Ficus sycomorus, Vachellia nilotica, and Cedrus sp. Such data confirmed the recurrence of Vachellia and Tamarix among the most common timbers found in ancient Egypt. Scanning electron microscope, Fourier transform spectroscopy, and synchrotron x-ray radiation diffraction were conducted to evaluate the archaeological wood deterioration. The formation of microcracks, biological degradation patterns (fungal colonization), or chemical characterization (accumulation of salts on and in-between wooden cells) were detected. SEM micrographs showed the presence of fungal hyphae and conidial spores on the wooden cells. Significant changes in the chemical wood composition and decrease in the crystallinity index were detected.     

Examining Possible Driftwood Use in Viking Age Icelandic Boats

While boat and ship graves are known from across northern Europe, and are particularly associated with the Viking Age, only seven examples of such monuments have been excavated in Iceland. Furthermore, no shipwrecks are known dating from this period in Iceland, and examples of boat timbers preserved by waterlogging are very rare. As such, the mineralized wood remains from these burials comprise the vast majority of direct archaeological evidence currently available for the boats used in daily life in early Iceland. This paper uses taxonomic identification of mineralized wood remains from the Icelandic boat graves, along with comparative data from Europe and Scandinavia, to discuss boat construction and repair in early Iceland, including the possibilities of driftwood utilization and the importation of boats from Norway. The economic and social significance of the practice of boat burial in Iceland is also explored, with regard to the importance of boats as transport and the limited availability of wood suitable for boat construction and repair.     

Doel 2: a second 14th‐century cog wrecked in den Deurganck,Doel, Belgium

In 2002, the preserved bottom part of a wreck was excavated, identified as a cog, and named Doel 2. An interdisciplinary research programme (2010–2014), revealed that the ship was constructed after 1328 with wood from northern Poland. Complete 3D‐registration of the timbers, and structural analysis showed it had a keelplank with a natural upward curve at the bow that served as a hook, and that most bottom planks were recaulked, among many other repairs. The ship ended up in ‘den Deurganck’, a creek near the Scheldt river where it was partially disassembled before the surviving remains were inverted, probably as a result of a flood. This paper presents the detailed recording and archaeological interpretation of the ship remains, and the results of the dendrochronological analysis.