A SIMPLE METHOD FOR THE IDENTIFICATION OF INDIGO

Abstract

Before commencing the conservation treatment of a fifteenth-century coffered ceiling in the convent of Santa Fe, Toledo, the painting materials were analyzed. Elemental analysis of the pigments was carried out by XRF spectrometry. Cross-sections were made of the samples for optical microscopy. The binding media and the varnish were identified by gas chromatography, by analyzing the fatty acids, terpenes and amino acids. Once the painting had been studied, consolidation treatment was applied using different materials according to the solubility of the paint layers. Animal glue was mainly used, and Paraloid B-72 to a lesser extent, as a preliminary to the structural reinforcement of the support.     

Conservation of a Chinese gu at the Canadian Conservation Institute

Abstract

Conservation and technical issues pertaining to the investigation of six mediaeval Spanish ceramic lustre fragments are reported. Assessment of methods and materials to replicate the lustre glazes indicates that the spray application of nacreous (pearlescent) pigments in combination with conventional inorganic pigments and transparent colorants in an acrylic lacquer gives good results. The salient optical features oflustre glazes and nacreous pigments are discussed. Scanning electron microscopy in conjunction with electron diffraction studies are employed to characterize the glaze and ceramic body composition of the fragments. Transmission electron microscopy indicates that a uniform dispersion of copper crystallites, c. 2-4nm in diameter, is responsible for the lustre effect in one sherd.     

CONSOLIDATION OF FRAGILE OBJECTS

Abstract

The condition before treatment and the subsequent consolidation of the wooden parts of an eighteenth century English fire engine are described. Experiments on a range of possible consolidants are outlined, and the application of polyvinyl butyral (Butvar B90, Monsanto) by both brushing and vacuum methods is presented. A closing discussion examines the relationship of the experimental findings to the practical application, the need for consolidation, and the final results of the treatment.     

An Inorganic Magnesium-based Consolidant for the Consolidation of Silica Sand (A Substitute for Weathered Sandstone): A Preliminary Exploration

ABSTRACT

Sandstone is a common sedimentary rock that is easily carved due to its weakly cemented fine grains and relatively low strength. Therefore, numerous large-scale grottoes in China are made of sandstone. However, these sandstone cultural heritage structures are often seriously damaged due to temperature and humidity changes, air pollution, biodeterioration, and repeated dissolution and crystallization of soluble salts. In general, it is imperative that a consolidant capable of providing cohesion by infilling pores between the stone grains is synthesized. In recent years, it has been reported that using organic consolidation materials for sandstone protection comes with various negative effects, such as a short lifetime, poor compatibility, and preservation damage. Using inorganic consolidation materials to protect sandstone seems to be one of the research trends for the future. Herein, this paper introduces a permeable, inorganic magnesium-based material (MMH solution) for silica sand consolidation. To assess this consolidant, the paper investigates the influence of varying molar ratios of MgO:MgCl₂·6H₂O:H₂O on properties such as penetration depth, consolidation weight, colour variation, and compressive strength. The results demonstrate that the molar ratios of MgO:MgCl₂·6H₂O:H₂O can significantly affect the consolidation performance. Additionally, it is believed that the MMH solution of MgO:MgCl₂·6H₂O:H₂O?=?5:1:16 can be successfully used for the consolidation of silica sand, as the cubic specimens’ surface micrographs show good compatibility between the consolidation product and sand grains. Experiments (i.e. weight loss rate and mineralogical compositions analysis) are performed to evaluate the cubic specimens’ water resistance properties after being immersed in water. Furthermore, the consolidation material’s failure mechanism as a self-sacrificing material is preliminarily analyzed. Results indicate that MMH solution is a promising conservation material that shows great potential for consolidating severely weathered sandstone.     

SOME ASPECTS OF THE CONSERVATION OF WORKS OF ART IN BUILDINGS OF NEW CONCRETE

Abstract

This paper deals with the materials used in conservation treatments in the first half of the twentieth century for the preservation and consolidation of wooden art objects from the Saxony region in Germany. The use of such materials must be seen as early attempts to find a conservation treatment for wood. The documentation of conservation treatments provides a reference to the application of oils and oil–resin mixtures. The results from the chemical analysis of samples of historic preservatives from the beginning to the middle of the twentieth century (so-called 'Puckelin') carried out by gas chromatography–mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) analysis confirm the use of tung oil as a drying oil, whereas the use of linseed oil cannot be excluded. Colophony and, probably, amber varnish were used as resinous constituents. There are indications that a conservation material dating from the second half of the twentieth century most likely contained rapeseed oil.     

THE CONSERVATION AND TECHNIQUE OF SILVER BANGLES DISCOVERED AT ROJDI,INDIA

Abstract

The treatment of two silver bangles found at Rojdi and dated c. 2000 b.c. is described. The bangles were separated by removing the hard incrustations with a 20% sodium hexametaphosphate solution and 15% acetic acid. Silver chloride was removed with a 25% solution of 0.88 ammonia and a 20% aqueous solution of ammonium thiosulphate.

Silver sulphide was removed in a 20% formic acid bath. Polyvinyl acetate was used for consolidation, and a coating of polymethyl methacrylate was applied. The silver was found to contain copper and lead. The causes of embrittlement and the manufacturing technique are discussed.     

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.     

CALCIUM CARBONATE WHITES

Abstract

The treatment of flaking pigment on two paintings, one on ceramic and the other on glass, is described; a brief history of painting on glass and ceramics places these works in context. The treatments are discussed in relation to other types of treatment for paintings on similar rigid supports. The longevity of the conservation methods used is discussed, as are the results of re-examination of the objects some years after the completion of the treatments.     

A new multi-purpose clamping table for the treatment of paintings on wood

Abstract

A new clamping table designed by the author for the treatment of paintings on wood is described. The table is capable of side, overhead and underneath clamping simultaneously, with an overall opening movement to allow one half of the panel to be moved away from the other half for final glueing.     

Stone reinforcement by calcite crystal precipitation induced by organic matrix macromolecules

Abstract

The weathering of stone monuments results in the leaching of calcite, with a consequent increase in porosity and decrease in integrity. A new method of consolidation uses organic matrix macromolecules extracted from Mytilus californianus shells to induce the precipitation of calcium carbonate within the pores of the stone. The procedure has been tested in the laboratory on samples of bioclastic limestone and dolostone, by measuring changes in total porosity, amount of water absorbed and superficial cohesion. The results appear to confirm the success of the treatment.     

Fabrication of an Ultrasonic Nebulizer: Rate of Flow and Performance Studies

ABSTRACT

This article describes how to build, in-house, a new type of ultrasonic nebulizer and presents the results of tests to determine its rate of aqueous flow and its performance during the transport of a collagen-based adhesive (ratio of adhesive actually delivered to adhesive misted). It also reports on a consolidation treatment case study carried out with the new ultrasonic misting prototype: the NebulA-MG 14. This case study was applied to powdery paint layers of a medium-sized oil painting on canvas, 111.5?×?86.5?cm. The new device is shown to be both reliable and effective, particularly for consolidating medium and large-sized works.     

Technique and treatment of the St Michael Weighing Souls in the Royal Convent of Santa Clara,Toledo, Spain

Abstract

The history, materials and technique of an early fifteenth-century wall painting, St Michael Weighing Souls, are described. The pigments are typical of mediaeval Spain but the methods by which they were applied show a sophisticated understanding of their optical properties. Complex mechanisms of deterioration in some areas of colour are discussed, together with the rationale, materials and methods used in the conservation treatment.     

Trust v. Antitrust

SUMMARY

The legal publishing industry in the United States went through a period of rapid consolidation during the last decade of the 20th century. Almost all United States publishers are now owned by foreign conglomerates that have a vast presence in the information business. The consequences of this change and consolidation of ownership has had far-reaching effects; some are already known, but some are certainly unknown at this time. In looking at the phenomenon, this article tries to give some historical perspective on legal publishing, examines the conglomerates as businesses (a “top down” approach), considers important legislation concerning databases, and wonders at the effects all this concentrated change may have on law libraries and the patrons they serve.     

THE CONSERVATION OF PYRITIC STONE ANTIQUITIES

Abstract

The occurrence and identification of ‘fossil disease’ in stone artifacts is described, together with details of techniques for the stabilization and consolidation of the specimens.     

Influence of Process Parameters on Chlorinated Biocide Decontamination by li-CO2 on Artificially Contaminated Model Materials

ABSTRACT

Previously, heavy use of biocides for the treatment of objects made of organic materials in museum collections (e.g. ethnographic, historical collections) was very common. Now suitable decontamination methods/technologies are being sought. A decontamination treatment by li-CO₂ was optimized that considered the specific requirements of museum objects. The treatment was tested on model materials artificially contaminated with biocide solutions containing dichlorodiphenyltrichloroethane (DDT), pentachlorophenol (PCP), lindane, and permethrin or cypermethrin. High decontamination was achieved for DDT, lindane, PCP, and permethrin on artificially biocide loaded wool and wood model materials. Optimal process parameter settings for li-CO₂ decontamination include a single 30?min cycle for woolen materials and three sequential 30?min cycles each for wood. These methods allow a reduction of at least 90% of all biocides for wool and between 70% and 85% for wood. Decontamination of the latter was more effective for less polar biocides as DDT and permethrin. Despite a significant improvement in decontamination for wood using co-solvents such as acetone, ethanol, and methyl tertiary-butyl ether (MTBE), their use is not recommended due to the increased risk of damage to the objects, in particular if a surface coating is present.     

Altération et nettoyage de pièces en argent doré

Abstract

By studying the mechanism of sulphation of silver-gilt objects in relation to the method used for gilding, its thickness and its appearance, it has been possible to develop a procedure for electrolytic treatment. The two-step treatment is carried out in a buffered solution of sodium nitrate and comprises cathodic reduction of the silver-based corrosion products followed by anodic dissolution of the reduced silver. The behaviour of the different materials is described, as well as certain limiting factors.     

Relining with Glass-Fiber Fabric

Abstract

Thermoplastic resins such as Butvar B98 and Acryloid B72 used as consolidants in solution may retain solvents which lower the glass transition temperature and plasticize the polymer. These effect scan be minimized by using solvents with low boiling points. This study is part of a continuing effort to examine consolidation of deteriorated wood in a systematic manner.     

Moiré fringe analysis of cradled panel paintings

Abstract

Cradle-related effects, such as ‘washboarding’ and tented flaking, were investigated by computer-aided moiré fringe analysis of panel models subjected to cycled changes in relative humidity. In-plane and out-of-plane displacements were recorded and compared for cradled and unreinforced panel models. These results were related to the behaviour of actual cradled panel paintings. Results indicate that restraint of warping increases in-plane strain due to swelling, and the strain distribution is in close correspondence with cradle restraint. Compressive strain, recorded over the fixed battens, and out-of-plane distortions in the exposed panel areas are discussed in relation to deformations and damages in cradled panel paintings.     

Some conservation problems encountered with turmeric on ethnographic objects

Abstract

The pH dependency of turmeric, used as a dye or pigment on ethnographic objects from the Santa Cruz Islands, can present a conservation problem. Great care must be taken with the cleaning, consolidation, repair, storage and display of objects of this nature. A section on the analysis of suspected turmeric is included.     

NOTE ON THE TECHNIQUE AND CONSERVATION OF SOME THANG-KA PAINTINGS

Abstract

The article is a concise report on the art historical as well as technical aspects of thang-ka paintings. It also describes briefly the traditional methods and materials employed in the execution of these paintings. The artists’ materials described in the literature are compared with actual findings as a result of analysis of pigments, binding media and other materials involved in the execution of the thang-ka paintings. An outline of the causes of deterioration of thang-kas is also mentioned. Finally, an extensive account is given of the method of treatment carried out in the author's laboratory.