THE SCIENTIFIC EXAMINATION OF THE POL YCHROMED SCULPTURE IN THE HERLIN ALTARPIECE

Abstract

An account is given of the examination of the polychromed sculpture in the Hedin altarpiece (1466) in Rothenburg old T. (W Germany). Analytical methods used, such as microscopy, wet chemical analysis, infrared spectrophotometry, thin-layer chromatography and gas-liquid chromatography are briefly described. Criteria for identification are summarized. Pigments identified are azurite, indigo, verdigris, green earth, madder, vermilion, red lead, lead white and carbon black. The binding medium is glue in matt areas. In other parts paints are mostly based on a resinous medium with varying amounts of oil. The materials identified in the applique relief brocades are compared with recipes described in the Liber Illuministarius from Tegernsee. Silver foil is used in producing translucent paint.     

VISION OF THE SERMON BY PAUL GAUGUIN: AN EXPLORATION OF MAKING AND MEANING

Abstract

In preparation for a major exhibition at the National Gallery of Scotland in 2005, a thorough technical examination of VISION OF THE SERMON by Paul Gauguin was undertaken for the first time since the painting's acquisition in 1925. An inter-disciplinary approach to the research was adopted in an attempt to assess how innovative were the materials and techniques employed by Gauguin in this iconic work. The importance of the unique customs and religious piety of Brittany in 1888 to the iconography of Vision is discussed, as well as the various ways in which the original appearance of the painting has altered over time. Changes have occurred through both the natural ageing of materials and as a result of human intervention, particularly an aqueous lining and reframing. Analysis suggests that the paint medium consists of several different drying oils, confounding years of speculation that it may contain wax. The discovery that the original surface coating contains beeswax and tallow has grave implications for the feasibility of future conservation treatments. Following Gauguin's accusation of plagiarism by Emile Bernard, a tentative comparison is made between Vision and the latter's Breton Women in the Meadow. This reveals that while compositional similarities exist, Vision is far more complex, both in conception and execution.     

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.     

THE CONSERVATION OF NON-METALLIC SEALS

Abstract

The conservation of non-metallic seals is an aspect of archival conservation which is all too often neglected.The authors show the most usual causes and forms of damage together with various methods of treatment. Among the aspects discussed are composition and manufacture; cleaning and repair of single and double-faced seals made of beeswax, shellac and other thermoplastic compounds; the conservation and repair of papered seals, together with seals and wafers applied en placard to documents; and methods of packing and storage used in the University of Glasgow Archives.     

ON THE OCCURRENCE OF BROMINE IN CORRODED SILVER

Abstract

Attention is drawn to the finding of silver bromide as a regular corrosion product on buried ancient silver. The chemical processes leading to this, and their relation to the burial environment, are discussed.     

THE PRESERVATION AND RESTORATION OF CANADIAN ETHNOGRAPHIC BASKETRY

Abstract

A method is given for the restoration and preservation of basketry. The treatment utilizes polyethylene glycol 600 with glycerine, dissolved in a 75% aqueous ethyl alcohol solution. No objectionable changes in the appearance have been observed.     

THE POLYCHROME DECORATION OF GREEK TERRACOTTAS

Abstract

This paper describes the composition of the pigments used for the decoration of Greek terracotta figurines, in the light of previous scientific analyses, and of supplementary analyses recently made by the Research Laboratory of the British Museum.     

DECREASING THE YELLOWING RATE OF DAMMAR VARNISH USING ANTIOXIDANTS

Abstract

The use of antioxidants to retard the yellowing rate of dammar varnish is investigated. A dammar formulation is given which should not significantly yellow in two to three hundred years of natural ageing. It is also shown that the choice of solvent when preparing a dammar varnish solution will affect yellowing rates of the resulting films.     

CORROSION AND CONSERVATION OF A SILVER VISCERAL VESSEL FROM THE BEGINNING OF THE SEVENTEENTH CENTURY

Abstract

Two different cleaning methods were found necessary to remove silver chloride corrosion products from different areas of a silver canopic vessel containing about 6% of copper. Two possible mechanisms of silver corrosion which could have led to the differing silver chloride corrosion products are put forward.     

THE DISCOVERY AND CONSERVATION OF AN ANCIENT EGYPTIAN LINEN TUNIC

Abstract

The archaeological evidence for dating a linen tunic found amongst other pieces from the Petrie Museum of Egyptian Archaeology, UCL, is weighed against the evidence from Carbon-14 dating. An account of the structure, conservation and mounting of the tunic is then given.     

ON THE CONSERVATION OF THE BAPTISTERY DOORS IN FLORENCE

Abstract

The causes of deterioration of the gilded bronze doors of the Baptistery in Florence have been examined and the mechanism of corrosion discussed. An apparatus for thermal conditioning has been proposed and tested either on the north door of the Baptistery, or on samples exposed to the urban atmosphere in Milan and by laboratory tests on an electrochemical model. The effectiveness of the proposed apparatus has been verified by weight losses, by assessing soluble salts, by visual observations, by local chemical microanalyses, by morphological examinations with a scanning electron microscope equipped with an X-spectrometer and by X-ray diffraction.     

THE POTENTIAL OF THE CANADIAN WINTER CLIMATE FOR THE FREEZE-DRYING OF DEGRADED WATERLOGGED WOOD

Abstract

The winter climatic conditions of much of Canada provide an ideal environment for freeze-drying. We have been attempting to use these conditions for the drying of large waterlogged timbers. In the freeze-drying process the wood is kept in a frozen state and the drying proceeds by sublimation. We are particularly concerned with the treatment of large timber which present great difficulties when treated by the accepted methods. A structure was built to keep snow and rain off the wood but which allowed air to pass over it. The structure was covered with polyethylene sheet to allow the sun to shine on the wood surface and heat it. Weight changes in the wood were measured with a load transducer and temperature wa followed with thermocouple probes. Temperature and relative humidity of the surrounding air were recorded instrumentally. The timbers were of several varieties of wood in various states of decomposition. All of the wood dried quickly and much of the water was removed. This technique appears to have the potential to treat large quantities of timber in an economic and simple way.     

THE RESTORATION OF TWO MARBLE STATUES BY ANTONIO CORRADINI

Abstract

The restoration of two early eighteenth-century marble statues by Antonio Corradini is described. Methylene chloride was used to remove plant stains. Sepiolite (magnesium silicate) and water drew out the dirt, and thick incrustations were removed with an ultrasonic dental tool. Incorrectly restored parts were remodelled according to contemporary prints, not in marble but using a casting procedure.     

THE CONSERVATION OF TAPESTRIES FOR MUSEUM DISPLAY

Abstract

A broad outline of the considerations which arise with regard to the conservation of a museum collection of tapestries is given in this paper. The various types of damage to, and deterioration of, tapestries is discussed.

Various methods of washing and dry cleaning, and the equipment necessary for these procedures, are reviewed, and a caution is included as to the necessity of testing all dyes for colour fastness in both water and any solvent used for dry cleaning. The equipment, materials and techniques of repair are discussed; three methods of repair being currently used in museums and specialist workshops — re-weaving, stitching on to a backing and the use of synthetic resins for impregnation and adhesion to a woven support. It is suggested in conclusion that the optimum method of repair in museums is stitching on to a backing. More research must be undertaken into the use of synthetic resins, and re-weaving usually alters the original appearance of the tapestry.

Finally, the need for specialised conservation staff in a museum with a tapestry collection is emphasised.     

BEST OF THE LITERATURE

Abstract

Welcome to the new “Best of the Literature” column of Public Services Quarterly. Every issue of this column will provide a survey of the best of the recent library literature either on a particular topic within public services (as with this first column on services to distance learners) or on public services broadly conceived. I hope that this column can highlight library literature that deserves to be read by every public services librarian. Ideally, readers of the column and I will collaborate to select the best of the literature. In that spirit, suggestions for great articles or special topics are always welcome.     

MAKING THE FIBRE GLASS REPLICA OF THE SUTTON ROO SHIP IMPRESSION

Abstract

It was decided to make a replica from the plaster mould of the Sutton Hoo ship impression using polyester resin reinforced with glass fibre matting and paper rope. For easy storage and transportation the replica was cast in twenty-five sections which could be bolted together. The problem of supporting these and preventing them from sagging or twisting out of shape was solved by using eighty accurately measured leg attachments fixed to the underside of the cast.     

THE USE OF THE AIRBRASIVE PROCESS FOR CLEANING ETHNOLOGICAL MATERIALS

Abstract

Ethnological specimens of many different materials can be dry cleaned mechanically by means of a grit-spraying unit. Plain and painted leather, corroded metal, beadwork, metallic embroidery, wood, ivory, bone, basketry, some paper, pottery, shell, some textiles and stone are items which can be cleaned with less disturbance to the surface than is often occasioned by the use of other methods. A specimen constructed of several materials may be cleaned by this one method rather than by several, thereby also avoiding the use of water, solvents or other chemicals. The powdered abrasives used are calcium magnesium carbonate, sodium bicarbonate, glass beads, and several grades of aluminium oxide. Silicone carbide powder is used occasionally for very hard corrosion products on metal.     

MAGNETIZATION OF SHARDS AS AN ASSISTANCE TO THE RECONSTRUCTION OF POTTERY VESSELS

Abstract

When pottery vessels are fired, they acquire a magnetization that is uniformly parallel with the ambient field in which they cool. If the vessels are subsequently broken, each shard retains its original magnetization which can be used either to supplement jigsaw fitting, particularly if several hundred shards are available from the same vessel, or to evaluate the shape of the original vessel when only a few, non-adjacent shards are available.