A case study of the conservation of the polychromed wooden choirloft of the seventeenth-century church at Carabuco,Bolivia

Abstract

The restoration of the seventeenth-century adobe church at Carabuco, Bolivia, offers a model of how to conduct the preservation of the Latin American cultural heritage at remote sites. This paper details the conservation of the church's polychromed wooden choirloft, which had previously been restored in 1765-66 after this and other portions of the church collapsed. The choirloft is made oflocally grown eucalyptus wood painted all over with a tempera-based medium. It was executed by a local artist whose style draws on local folk-art traditions while reinterpreting European Renaissance decorative schemes. The choirloft conservation project had two goals: to guarantee its structural integrity and to stabilize the decorative paint layers. These goals were accomplished in a four-month conservation project which formed part of a larger effort to restore the church.     

The repair of parchlllent: Filling

Abstract

Parchment is produced by processing the dermal layer of animal hide through limited mechanical and chemical treatment and then drying it under tension. The weak condition of many historical objects made of this material is caused by chemical, biological and mechanical degradation. Repairing these objects by filling gaps with parchment or paper patches may be inadvisable, due to important differences in intrinsic strength, which can create tensions between old and new materials. Alternative filling methods may be used, consisting of the application of solid materials in the form of a powder or a suspension, used to create a solid sheet of reconstituted parchment. The solids may consist of any kind of collagenous material (powdered parchment or hide, gelatin), paper or a combination of the two. Published methods describe preliminary treatments (e.g.relaxation), application media (water, solvents, additives), use of additional consolidating membranes (Japanese paper, goldbeater's skin), use of adhesives for pasting and surface consolidation purposes, preparation of mechanically isotropic templates for infills and tinting with synthetic dyes. A comparative investigation of methods confirms that the mechanical properties achieved in these infills, such as tensile strength and elasticity, as well as their reproducibility, are acceptable for application in conservation practice.     

Action Mechanism of Sticky Rice-Paste-Modified Site Soil: A Traditional Chinese Cementitious Material

ABSTRACT

Sticky rice paste is a viscous material commonly used in traditional Chinese construction. It has the basic properties of high viscosity and viscoelasticity, good corrosion and weather resistance, and a small coefficient of expansion. Sticky rice paste is usually added to site soils to modify their basic physical and mechanical properties. This study found that gelatinized sticky rice-paste-modified site soils have clearly improved physical and mechanical properties compared to 20 and 100°C water-modified soils when 1% (wt%) sticky rice paste is added as the soil modifier. The liquid and plastic limits, and the plastic index of the soil are improved upon modification, to 27.4, 17.7, and 9.7%, respectively. The unconfined compressive strength and hydraulic conductivity were significantly increased and reduced, respectively. In addition, there was a reduction in the rate of disintegration by water, while the water resistance of the soil was improved. X-ray diffraction, Fourier transform infrared, and thermogravimetry/differential scanning calorimetry studies reveal that the improved properties arise through physical processes between the sticky rice paste and the soil. Scanning electron microscopy reveals that dispersed branched-chain sticky rice-paste molecules extensively infiltrate the surfaces of the soil particles on the nanoscale and become attached to them to form a good adhesive colloid that solidifies the soil particles after water evaporation, resulting in a compact structure.     

Condition of Reinforced Concrete Structures and Their Degradation Mechanism at the Former Auschwitz Concentration and Extermination Camp

ABSTRACT

This paper presents the results of investigations on reinforced concrete structures present in the former Auschwitz I and Auschwitz II-Birkenau concentration and extermination camp. Field inspection employing the non-destructive method of reinforcement potential measurement according to the ASTM-C 876–15 standard, followed by laboratory investigations performed on genuine historic reinforced concrete samples collected from the former Auschwitz camp, allowed assessment of the actual condition of this 70-year-old construction material. Electrochemical potential measurements allowed mapping of the regions characterized by enhanced reinforcement corrosion risk and the regions of its immunity. The composition of concrete, water absorbency, content of detrimental salts, and degree and profile of carbonation as well as mechanical properties were evaluated. Results revealed the most common and probable mechanism responsible for degradation of the reinforced concrete structures in the former Auschwitz camp.     

Why Do Historical Beeswax Seals Become Brittle Over Time?

ABSTRACT

Mechanical properties of aged beeswax were studied by an indirect measurement, using hydrogenated beeswax as a model material. The adequacy of the model was evaluated by comparison of its chemical composition and thermal properties with those of samples of historical beeswax. It was found that the gradual decrease in content of unsaturated compounds in beeswax contributes significantly to changes of its mechanical properties. As a consequence, beeswax artefacts become increasingly prone to mechanical damage during natural ageing. Understanding the difference between mechanical properties of recent and historical beeswax is primarily important from the point of view of safe handling and storage of such artefacts. Besides, this knowledge could help conservation scientists, e. g. when preparing model samples for testing new conservation methods.     

充分发挥水土保持期刊在我国西部大开发中的作用

分析水土保持期刊在我国西部大开发中的作用.介绍<水土保持学报><水土保持通报><水土保持研究>为西北大开发服务的做法和体会.     

Marine Aerosol Weathering of Mediterranean Calcarenite Stone: Durability of Ethyl Silicate,Nano Ca(OH)2, Nano SiO2, and Nanostructured Consolidating Products

ABSTRACT

Calcarenite stone samples from a historic building (Bizerte, Tunisia) were collected and treated under different environmental conditions with several consolidating products: alkoxysilane (ethyl silicate), a surfactant-templated novel sol–gel, Ca(OH)₂, and SiO₂ nanoparticles. These were subjected to marine aerosol accelerated aging cycles and studied by several non-destructive tests and techniques to assess the stability of the products. Results show that weathering caused by salt crystallization is not inhibited but it is slowed down due to the enhancement of superficial mechanical properties (surface cohesion and micro-hardness) achieved after one month of treatments application. A high or low relative humidity of the consolidation environment significantly affects the final mechanical and aesthetical physical properties and therefore conditions the durability of the treated substrates, even producing higher damage than observed in the blank specimens, depending on the product.     

Materials and techniques in the pictorial oeuvre of Lucio Fontana

Abstract

The painting materials used by Lucio Fontana were investigated through the analysis of 28 Spatial Concept works created between the early 1950s and the artist's death in 1968. The pictorial media were analyzed by means of numerous techniques including Fourier transform infrared spectroscopy, pyrolysis-gas chromatography–mass spectrometry, scanning electron microscopy, and X-ray fluorescence. This study has provided a more complete understanding of the artist's technique, as it was found that Lucio Fontana had already begun experimenting with new synthetic pictorial and binding media such as alkyds and polyvinyl acetates at the beginning of the 1950s, and polyesters during the early 1960s. Although he never abandoned the use of commercial oil paints, Fontana's application of these new materials continued in an infinitely varied search for innovative expressive effects. The characterization results explain the physical and mechanical properties of the paint layers, and may be correlated with the conservation state of the works analyzed. All the results have been compiled and are discussed together with the artist's practices and their evolution over time.     

Use of Polarised Light Microscopy to Improve Conservation of Parchment

ABSTRACT

The preservation state of parchment primarily depends on the structure of the collagen fibre network, which in turn is responsible for optical anisotropy, i.e. birefringence. Polarised light microscopy can therefore be used as a non-invasive technique that allows recording of birefringence distribution in the parchment, which directly relates to stress–strain distribution. Using samples from diverse sources (commercial parchment, parchment used by restorers for book binding, and parchment fabricated for the purpose of this study), we assessed the capability of polarised light microscopy for various diagnostics. We performed, for instance, identification of gelatinised regions, layered or ?brous regions in parchment cross section, qualitative analysis of parchment fat content (lipids), observation of stress-induced patterns resulting from tensile tests, and observation of water diffusion. These proof-of-principle experiments extend the capability of polarised light microscopy far beyond its common use and open the path to its deployment in conservation studies.     

English Artists' Paper,Renaissance to Regency

Abstract

Oil paints dry by polymerization. This 'drying' process may be substantially complete and the surface of the paint film dry to the touch within weeks, but measurable changes continue for years. Other, slower processes also continue, primarily hydrolysis of glyceride esters. This produces carboxylic acid groups as either free fatty acids (in the case of acid groups that have not reacted otherwise) or acid groups bound to the crosslinked oil matrix (in the case of acid groups that have engaged in polymerization reactions). These may react with pigments to form carboxylate salts (called soaps in the case of a fatty acid). These changes affect the physical properties of the paint and the way that conservation treatments affect it. This paper examines the extent of hydrolysis and soap formation in some naturally aged drying oil and paint films, the extractability of these materials in organic solvents, and measured and predicted changes over time in the physical properties of naturally aged paint films. Long-term physical and mechanical changes due to aging are minor compared to those produced by overcleaning or excessive exposure to heat.     

Natural polymers as alternative consolidants for the preservation of waterlogged archaeological wood

In recent years, there has been increased interest in examining alternative polymers for the conservation of archaeological artefacts, particularly waterlogged timbers, providing better, renewable, greener alternatives to poly(ethylene glycol) (PEG). The degradation of PEG consolidants in the timbers of the sixteenth century warship Mary Rose has been examined and the rheological and thermal properties of PEG have been compared with its monomethyl and dimethyl ethers and several polysaccharide consolidants (chitosan, guar, and 2-hydroxyethyl cellulose) in order to evaluate their potential as alternative consolidants for the conservation of waterlogged wooden artefacts. Additionally, the effect of the polymers on the archaeological wood was characterised by thermogravimetric analysis and solid-state nuclear magnetic resonance spectroscopy. The results suggest that the future of conservation technologies lies with polysaccharide consolidant materials, which show enhanced compatibility with wooden artefacts with no detectable side effects while also being cheap, with extremely low toxicity, renewable, and sustainably resourced.     

Painting Hinemihi by numbers: Peoples-based conservation and the paint analysis of Hinemihi's carvings

This study describes the analysis of paint samples from carvings belonging to Hinemihi, the Maori meeting house, Clandon Park, Surrey, UK. The assessment of physical evidence contained within Hinemihi's built fabric (along with historiographic research of archival sources and oral histories) has formed a key part of the information gathering process during the current conservation project. The production of such data provides an opportunity for a dialogue that is essential for effective decision-making within participatory conservation projects. From this, it is evident that the use of paint analysis, in deciding the eventual painted scheme for a restored Hinemihi, is settled within a broader dialogue about the conception, use, and management of Hinemihi as a Maori cultural centre, as built heritage, and as an object of conservation. Therefore, the value of material analysis is considered in relation to the potential that this information has to engage a community of users in designing an effective conservation response that seeks to balance the opportunities and constraints of the cultural and physical landscapes that surround Hinemihi and Clandon Park.     

An investigation of the use of cellulose-based materials to gap-fill wooden objects†

The conservation of wooden objects is complicated by their response to changes in their environment. In particular, filling voids in wooden objects can be difficult when their dimensions might be expected to alter over time. A short survey of conservators showed that a wide variety of materials have been, and are being used for this purpose. Following conservation work undertaken on a wooden coffin, the author wished to investigate the properties of cellulosic materials and their suitability in the conservation of wooden objects. This paper shares the results of experiments that were conducted to determine the way in which hydroxypropyl cellulose (HPC) and paper pulp fills respond in various conditions, as compared to other fill materials used by conservators. The compatibility of the HPC and paper pulp fills with wood is satisfactory enough to be able to recommend their use in the conservation of wooden artefacts, but ideally further experiments would be carried out, and on a wider variety of fill materials.     

古籍历史修复遗存的形式、处理措施及启示

[目的 /意义]历史修复遗存是古籍的组成部分,是新的古籍修复周期处理的对象,研究古籍历史修复遗存不仅能丰富古籍修复技术,更能提高古籍修复质量.[方法/过程]分别运用归纳法和案例法研究古籍历史修复遗存的形式及处理措施.[结果/结论]古籍历史修复遗存形式包括修复材料、修复方法及其印记等.古籍历史修复遗存处理应依据具体情况分...     

Evaluation of the use of Funori for consolidation of powdering paint layers in wall paintings

Funori is a polysaccharide-based adhesive extracted from seaweeds and is generally used in the conservation of easel paintings for the consolidation of matte paint. It is appreciated since it does not change the optical properties of the consolidated materials and its mechanical properties do not change with ageing. Because of these characteristics, this research focused on the evaluation of Funori as a suitable material for the consolidation of powdering paint layers in wall paintings. Tests were carried out where Funori was applied onto painted plaster replicas, which were then artificially aged and investigated in order to evaluate the material's behaviour according to the specific properties and conditions of wall paintings. The effectiveness of the consolidation was evaluated from the point of view of adhesive power, as well as the interactions of Funori with some physical properties of the consolidated painting, such as colour and water vapour permeability and, therefore, its resistance to accelerated ageing and biological colonization. In addition, the behaviour of Funori applied on plasters contaminated with soluble salts, a frequent condition in wall paintings, was also evaluated.     

Material Weathering and Structural Damage in Historic Adobe Constructions in Spain: Preliminary Results of a Quantitative Approach

ABSTRACT

This article presents the study of the main phenomena of material weathering and structural damage that affect traditional architecture built in adobe, analysing the damage found in 553 case studies, representative of different technical varieties of adobe construction in Spain. The analysis methodology proposed in this text made it possible to quantify and identify the risks of damage appearing, establishing its impact and identifying its main mechanisms and causes. At the same time, the behaviour of adobe construction systems was further studied, observing how specific modifications in technique can promote or hinder deterioration and establishing the probable causes of the different responses to these phenomena.     

Deterioration Assessment and Conservation of a Heavily Degraded Korean Stone Buddha from the Ninth Century

Abstract

The standing Buddha image of Jincheon in the Republic of Korea created in the fourth year of Taehwa is engraved on a darkgray rock wall of shale. The front face has a backward inclination, meeting the strike of N40°W almost vertically. The host rock contains well-developed fine laminations and stratifications, and has small and large discontinuous planes irregularly distributed. Exfoliations make it hard to make out each part of the body. The surface of the surrounding rocks is severely contaminated with lichen and Bryophyta, and plant roots aggravate the mechanical and biological weathering. The rocks went through a series of conservation treatments, which consisted of dry cleaning followed by wet cleaning using distilled water. Broken or cracked parts were filled in or glued together using epoxy resin, surfaces with exfoliations were treated with ethyl silicate to become water-repellent and hardened. The color of the repaired parts was matched to harmonize with the rest of the image. Drainage was created to divert rainwater from the slope above away from the image, and surrounding plants were removed to control lichen growth. The bedrock of the Buddha image is deteriorated in its functions due to the surface weathering, therefore it is necessary to implement long-term monitoring and to search for comprehensive conservation solutions.     

碳纤维在档案修裱黏合剂中改性应用的探析

目前的档案修裱黏合剂普遍使用纯淀粉浆糊,但纯淀粉浆糊形成的淀粉膜抗拉力弱、脆性大、易断裂,使得修裱后的纸张强度与耐久性不高。针对这一问题,将淀粉浆糊中添加不同比例的碳纤维进行改性,通过检测纯淀粉浆糊与改性淀粉浆糊所修裱的纸张的物理与化学性能,包括耐折度、撕裂度、抗张强度、pH值、白度,对比分析不同比例碳纤维改性淀粉浆糊对档案纸张强度的影响。结果表明,当碳纤维在淀粉中的质量比为1%时,修裱纸张的各项性能得到了显著提升。     

Humidity Control in Historic Buildings in Denmark

ABSTRACT

Historic buildings in Denmark have a high relative humidity (RH) all year, so the interiors are exposed to biological degradation. The acceptable range for RH is 60–70%, which is higher than the usual recommendations for museums and galleries. There are two options for humidity control: conservation heating or mechanical dehumidification. Calculation of the energy performance of a generic building was used to determine which method is the most efficient. Studies of a cottage in Liselund Park, and of two medieval churches in Hellerup and Vemb have confirmed these predictions: dehumidification is less energy consuming than conservation heating in buildings with poor thermal insulation and a moderate air infiltration rate (AER?<?0.6?h^?1). Dehumidification is suitable for historic buildings, where heating is not needed for human comfort. A condensing dehumidifier uses less than half the energy per kg water compared to an absorption dehumidifier. But it does not work at temperatures below 2°C. The combination of a condensing dehumidifier and a little heating to prevent frost is the most energy efficient solution for humidity control. These results are only valid in mild and humid climatic conditions similar to Denmark.     

无碳复写纸档案字迹材料耐久性研究

无碳复写纸档案字迹材料耐久性与环境温湿度、酸碱性物质、有机溶剂、微胶囊牢度、显色剂性能等保存环境和内在因素密切相关。本文就影响无碳复写纸档案字迹材料耐久性的温湿度、酸碱、有机溶剂、微胶囊牢度、显色剂性能等因素进行研究和分析。