Van Eyck: Notes on the Material Aspects

Notes on the Material Aspects The recently discovered metalpoint drawing has convincingly been attributed to Jan van Eyck or his immediate environment.1 Measuring 254 x 187 mm, the drawing shows a large crowd of bystanders around the Crucifixion. It bears an obvious relationship to the left wing of a diptych by Jan van Eyck, now in the Metropolitan Museum of Art in New York.2 A technical examination of the sheet may shed some light on the genesis of this drawing in particular, and workshop processes in Jan van Eyck’s studio in general. Although the drawing has recently been the subject of technical investigations (see the appendix in this volume), there is a need to address a number of insufficiently understood material aspects.3 A Rag Paper without Texture? In our analyses of the drawing, we began by attempting to identify the substrate on which it was made. Under the microscope we found that it was executed on a linen rag paper. The examination also showed that the paper was primed with a coating.4 Elemental analyses indicated that the coating could be a calcium phosphate,5 and indeed, polarized light microscopy verified that the particles of the coating had all the optical properties of bone white.6 This was further confirmed with X-ray powder diffraction.7 This coating appeared to consist of hydroxyapatite, in other words the basic structure of bone white.8 A protein was identified as the binding medium.9 This bone-white coating makes it difficult to detect the pattern of chain lines and laid lines of the paper underneath. The detection of any trace of a watermark that could have given us clues about the paper’s date and origin was similarly impossible. No watermark was discernible in either raking light or transmitted light. The bone-white layer served as the substrate for the metalpoint drawing. It provided a smooth surface, yet with some abrasive ‘tooth’ for the metal to adhere to. The application of such coatings is entirely consistent with the methods described in historical sources for the preparation of paper for metalpoint drawings.10 Such texts prescribe the calcination of animal bones to white powder. Usually poultry bones are used, because their hollow structure allows a faster reaction. Mixed to a watery suspension with dilute gelatinous animal glue, the bone-white paint was applied with a brush to give the paper a coating of the desired thickness.11 Under the microscope this material appeared as a relatively smooth layer, 0.03 mm thick, effectively covering the paper fibres. Once the surface of the coating was burnished to a perfect ivory-white smoothness, it was ready to receive the tracing with a metalpoint.12 Notes on the Material Aspects Arie Wallert, Birgit Reissland, Luc Megens An Eyckian Crucifixion Explored: Ten Essays on a Drawing 24 Notes on the Material Aspects 25 Not One But Two Metal Points A medieval manuscript text, included by Jehan le Bègue in a compilation of technical treatises (Paris, Bibliothèque nationale de France), indicates that several types of metal and alloys could be used for drawing on bonewhite coatings, ‘so you would be able to draw upon them with black chalk, or with a stylus, either of gold, silver, tin or copper’.13 In this case, the drawing was made with at least two different styluses. There are lines in silverpoint and lines in goldpoint. The silverpoint lines are not made with pure silver, but rather an alloy of silver and copper. The ratio of silver to copper resembles that of the composition of one of the styluses used for the famous study for the work known as the Portrait of Cardinal Niccolò Albergati in Dresden (fig. 61).14 The lines in silverpoint on the present drawing are marked by significant amounts of mercury. This element has recently been established in other metalpoint drawings.15 Other parts of the drawing were done in goldpoint. The goldpoint lines were likewise not done with the pure metal, but with an alloy in which fairly large amounts of copper and zinc and smaller amounts of silver seem to be present.16 It was not immediately clear why Van Eyck would have used those two different styluses. The traces of both metalpoints give fairly similar grey lines initially. Micro-spot elemental analyses did not allow us to draw any conclusions about the distributions of gold or silver lines over the whole drawing, or their possible function. The whole drawing is executed in these two metalpoints: gold and silver alloys. The lettering of the titulus may have been done in ink, but there is no absolute certainty even about those letters. The only unquestionably positive identification for an iron gall ink is in the rather heavy-handed outline around the rock in the lower left foreground. This was probably not done with a fine brush. Form and contour rather suggest the use of a pointed quill. This ink line, which stands out quite prominently in UV, was clearly added by a later hand. At this point, the examination of the drawing in the infrared wavelengths proved useful.17 A peculiar change in colour of both metal tracings appeared to be of significance. Initially, both metalpoints would have yielded similar cool grey marks on the abrasive bone-white ground. These marks, however, are extremely thin. It is estimated that the total amount of metal particles deposited on to the bone-white preparation would add up to some tens of µg per square centimetre. This would amount to just some nanometres of thickness of material. The metal deposited therefore has a large surface relative to its volume. Such large, exposed surfaces make the metal particles invitingly open to influences from the environment. Lines in silverpoint are particularly inclined to react with even the smallest amounts of sulphides in the air or in the substrate. This results in a relatively fast change in colour. Fresh silverpoint lines on a test panel showed a notable change in colour from a cool bluish-grey to a warmer purplish-grey in just two weeks. Lines done in gold or gold alloys remain unchanged, however. These changes are too subtle to be distinguished on the present drawing with the unaided eye. They can be observed, though, using infrared reflectography. Metals, and therefore the metallic lines of a metalpoint drawing, are usually not transparent to infrared radiation. An Eyckian Crucifixion Explored: Ten Essays on a Drawing 26 Fig. 9 The Rotterdam Crucifixion in infrared reflectogram, showing the goldpoint lines very prominently, whereas the silverpoint lines are largely invisible Notes on the Material Aspects 27 They tend to absorb the longer wavelength ranges, and so often appear as black in infrared reflectograms. Over time, however, the metallic silverpoint lines had deteriorated and effectively converted from metallic silver lines into silver sulphide (AgS) lines. Those lines, no longer being metallic, became increasingly translucent to infrared radiation.18 In the reflectogram of the drawing, the lines in silverpoint, no longer purely metallic and thus no longer fully infrared absorbent, were largely invisible, which meant that the whole landscape and the city of Jerusalem behind the scene of the Crucifixion all but disappeared in the infrared image (fig. 9). The goldpoint lines, on the other hand, remained quite prominent in the reflectogram – more so, in fact, than in normal light. This is particularly evident in the expression on St John’s face and in the dramatic figure of Mary Magdalene (fig. 10). In the reflectogram it becomes much more evident that the drawing has a stronger emphasis on the dramatic aspects of the event than the painting in the Metropolitan Museum of Art. The crucified thief on the upper right of the drawing has all the signs of suffering. His body – drawn in goldpoint – shows up much better in the reflectogram than in the drawing itself; it is more twisted and contorted and, in his agony, his right leg has come loose from the cross (fig. 11). In the painting, the bodies of the thieves to the left and right of Christ draw much less attention. As we have said, it is not immediately clear whether the use of goldpoint or silverpoint represents a different stage in the execution of the drawing. It is hard to imagine that the clubs and spears emerging from behind the group of horsemen could have been drawn first, without having the shape of the crowd below to support them. The position of the rider with the fur-lined bonnet (drawn primarily in silverpoint), however, is determined by the two figures drawn in goldpoint in front of and behind the horse’s head (fig. 12). There, one would expect the use of goldpoint to precede the silverpoint. The use of either silver or gold does not seem to be reserved for specific figures in the drawing, nor could we deduce that the use of gold represents a specific stage in the process – for instance, that the first lines were done in gold and the drawing was then further worked out in silver, or vice versa. The execution of the garb of the riders to the left is of a very fine dense hatching, running at very acute angles, almost parallel to the main outlines. The changes of movement and planes that can be observed in the angular pleats and folds of the gambeson worn by the rider at the foot of the cross are executed in a dense network of subtle strokes supported by heavier but soft contours (fig. 13). The manner in which the horses and the group of women around Mary are set off against the background is remarkably similar to the way the shape of Brother Leo is set off with dense hatching against the rocky background in the underdrawing of St Francis Receiving the Stigmata (Turin, Galleria Sabauda) or the underdrawing of equivalent figures on the New York panel.19 The volumes of the horses – one urinating in gold, defecating in silver – are similarly modelled with forceful parallel hatching indicating the shadows around the bodies. The outlines of the horses are long and powerful, and filled with brisk, shorter modelling strokes that convincingly suggest the movement of strong muscles under a smooth, velvety hide. The outlines of the horses, An Eyckian Crucifixion Explored: Ten Essays on a Drawing 28 Fig. 10 Detail of St John and Mary Magdalene in the Rotterdam Crucifixion in infrared and normal light Fig. 11 Detail with the bad thief at Christ’s left hand in the Rotterdam Crucifixion in infrared and normal light Notes on the Material Aspects 29 Fig. 12 Detail of the crowd in the background of the Rotterdam Crucifixion in infrared and normal light with long continuous strokes, are largely in silverpoint; the sturdier parallel hatchings and crosshatchings, placed rectangularly around these contours to bring the figures into relief and to indicate shadow, are primarily done in goldpoint. The lines in silverpoint tend to be longer and are much thinner, whereas the lines in goldpoint are broader and are situated in darker, shadowfilled areas. This may be due to the characteristics of the drawing material. It is not possible to obtain darker areas just by putting more pressure on the stylus when using metalpoint. Pressing harder does not produce darker lines, it simply makes grooves in the paper.20 The only way to obtain depth in metalpoint is by repeatedly returning to the same place, or having a broader stylus tip so that more metal is deposited on that spot than on other areas. A silverpoint is harder than a goldpoint. The softer goldpoints consequently tend to deposit more material in a single stroke than the silverpoint. It therefore comes as no surprise that we find most of the goldpoint touches in areas where the greatest contrast is needed: the figure groups around the cross and in the foreground. We do not find the goldpoint used in the rather low-contrast part of the hazy background with the city of Jerusalem. The use of different metals in one drawing may not be exceptional. The statement in the Le Bègue manuscript that one could draw ‘with a stylus, either of gold, silver, tin or copper’ already points in that direction. But there is other convincing historical evidence that most fifteenth-century artists worked with more than one type of metal. A painting from the studio of Dieric Bouts, St Luke Painting the Virgin, depicts the evangelist in the act of drawing. He is shown holding a stylus with a different metal point at each end (fig. 14). A similar two-tipped stylus can be seen in the St Luke Drawing the Madonna that is attributed to Hugo van der Goes (fig. 15) and in Jan Gossaert's St Luke Drawing the Madonna (Vienna, Kunsthistorisches Museum). The styluses in these works are more than simple drawing tools, they are examples of meticulous craftsmanship. Their two tips were presumably made of different metals or their alloys with differing physical properties, for instance gold and silver, and probably also varied in the shape of their tip. Such a drawing tool makes it possible to draw lines of varying width and morphology, allowing the artist to accomplish subtle but effective differentiations within the drawing. A two-pointed drawing tool lets the artist switch quickly between the points and promotes a fluent drawing process. The present drawing is important evidence of such a studio practice. Fig. 13 Detail of horses in the Rotterdam Crucifixion in infrared and normal light The Lining Paper The presence of a lining paper on the back of the original drawing is a major impediment to establishing a watermark. It was pasted with starch directly on to the verso of the original, which was covered with indigo pigment.21 The lining paper is also hand-made with a clearly visible pattern of chain lines and laid lines. It has a watermark, type gothic letter P with a forked stem. In his essay Albert Elen gives a detailed analysis of the watermark and explains its limited relevance to the dating of the drawing. An Eyckian Crucifixion Explored: Ten Essays on a Drawing 30 Notes on the Material Aspects 31 Fig. 14 Dieric Bouts (workshop of), St Luke Drawing the Virgin (detail), c. 1460, oil on panel transferred to canvas, 109 x 86.5 cm, National Trust, Penrhyn Castle A Dark Blue Prepared Verso and Heavy Incisions in the Drawing At some point the lining paper at the lower right corner had been torn away, revealing the dark blue coloured surface of the original paper (fig. 16).22 The prepared verso is also visible through a small Y-shaped wormhole at lower left, which indicates that the preparation was probably applied all over the back. The dark blue colour was identified as indigo pigment deposited on the cellulose fibres.23 This kind of preparation of the reverse is part of a common transfer technique for drawings. We know of many examples throughout the centuries.24 Their purpose is to transfer the outlines of the composition of the drawing on a scale of 1:1 on to an underlying support such as a sheet of paper, a copper plate for printing or a prepared panel for painting. Cheap red or black pigment powders such as red or black chalk or charcoal are usually used to provide a contrast to the colour of the new substrate. The use of expensive indigo, although it may seem uncommon, makes sense in the context of an artist’s workshop. Indigo has the advantage of being a very finely powdered colourant, leaving easily recognisable traces with the use of limited amounts of material. Along with carbon black it is probably the most effective tracing material. In order to transfer the drawing, the lines are traced with a pointed instrument that will not leave coloured marks on the drawing. The most common tool, for this reason, is a blunt iron stylus. The pressure applied to incise the outlines of the drawing leaves indentations in the paper. In the present drawing they are broad and rather rigid in comparison with the delicate, smooth and flowing lines of the metalpoint. Elemental analysis revealed the presence of iron in the incisions.25 This suggests that in our case a relatively blunt iron pin was used (fig. 17). A Severely Discoloured Intermediate Layer While an iron stylus does not leave coloured lines on a common drawing paper, however, it would be very likely to leave marks on a paper coated with a bone-white preparation layer. The presence of a transparent – now brownish discoloured – varnish-like layer that covers the entire drawing may be related to attempts to prevent that from happening. This coating is extremely thin, and actually consists of two layers – starch underneath a protein glue, each layer being 1/1000 mm thick.26 The spatter-like discolouration pattern suggests that one or both layers were not brushed directly on to the delicate surface of the metalpoint drawing. Instead, the glue/starch solutions were probably applied by moving a curved wooden stick over a stiff-bristled brush. For centuries, this method was used for fixing friable surfaces. It leads to a relatively homogeneous distribution of droplets with comparable diameters, but with the chance of some irregularities (fig. 18). Both the starch and the protein glue were initially transparent and invisible. The mixture is known to discolour over time, however. Applying an iron stylus over such a coating might not leave any marks. Without such a coating, the ‘blind’ iron stylus would probably not be as blind as one would wish, and would still leave visible traces. It is nonetheless possible that the coatings might have been applied at a later stage, probably even at differing times and for other purposes. Fig. 15 Hugo van der Goes (attributed to), St Luke Drawing the Madonna (detail), c. 1470, oil on panel, 104 x 62.5 cm, Museu Nacional de Arte Antiga, Lisbon An Eyckian Crucifixion Explored: Ten Essays on a Drawing 32 Notes on the Material Aspects 33 Fig. 16 Detail of the verso of the Rotterdam Crucifixion revealing the verso of the original paper coated with indigo pigment Conclusion The materials that we have found and their application are entirely consistent with the drawing’s having been made by Jan van Eyck himself, or in his studio, around the 1430s. The whole drawing is executed in metalpoint on paper with a bone-white coating. The grooves and thicker lines that have been observed are not ink lines, but rather notches from a ‘blind stylus’ that was used to transfer the main outlines of the image. X-ray fluorescence measurements indicate that this must have been done with an iron stylus. The pressure used in this transfer process not only caused these indentations, it also resulted in the depositing of iron on the abrasive bone-white coating. In a way, one could consider this to be a ‘non-intentional, three-metallic’ metalpoint drawing. Gold and silver lines being intentional; iron traces being unintentional. It has been convincingly argued elsewhere that the handling of these materials is so similar to that of unquestioned drawings and underdrawings by Jan van Eyck that the present drawing can be attributed to Jan van Eyck with a fair degree of confidence.27 Fig. 17 Detail of the Rotterdam Crucifixion, in raking light. Heavyhanded indentations retrace the outlines of the original drawing Fig. 18 Detail of the Rotterdam Crucifixion, discoloured varnishlike surface layer with irregular spatter pattern An Eyckian Crucifixion Explored: Ten Essays on a Drawing 34 Notes on the Material Aspects 35 Contents Foreword 4 Sjarel Ex Introduction 6 Friso Lammertse, Albert J. Elen 1 The Discovery 8 Friso Lammertse 2 Notes on the Material Aspects 24 Arie Wallert, Birgit Reissland, Luc Megens 3 Two Papers and a Watermark 36 Albert J. Elen 4 The Use of Goldpoint and Silverpoint in the Fifteenth Century 44 An Van Camp 5 Attribution, Style and Date 58 Fritz Koreny 6 Reflections, Models and Possible Function 70 Guido Messling 7 Copying and Beyond: the Multiple Functions of Early Netherlandish Drawings 80 Stephanie Buck 8 Some Eyckian Drawings and Miniatures in the Context of the Drawing 94 Till-Holger Borchert 9 The Drawing and Colour 108 Stephan Kemperdick 10 The Relationship Between the Rotterdam Drawing and the New York Painting 116 Maryan W. Ainsworth Summary of Methods for Examination of the Drawing 134 Notes 142 Bibliography 152 Biographies 158 museum van boijmans beuningen Contents An Eyckian Crucifixion Explored: Ten Essays on a Drawing 2 Contents 3 Appendix Summary of Methods for Examination of the Drawing Composition of the Support •฀Paper฀identified฀with฀digital฀microscopy฀(Hirox:฀KH-7700฀digital฀microscope฀ with 2.11 megapixel CCD sensor, res. max. 10,000 x 10,000 pixels, magnifications 35x – 2000x: fibre morphology). •฀Fibres฀for฀paper฀identified฀as฀linen฀with฀polarized฀light฀microscopy฀(PLM:฀in฀ plain transmitted and polarized light, with a Zeiss Standard 17 microscope, (mag. 200x): multiple sided cylindrical filaments with nodes at intervals and fine pointed edges), and microchemical test (MCA: potassium iodide – sulphuric acid stain). Preparation of the Paper Identified as Bone White, i.e. Hydroxyapatite •฀With฀elemental฀analyses฀by฀energy฀dispersive฀X-ray฀fluorescence฀ spectrometry (XRF: ARTAX µ-XRF spectrometer, 50kV, 600µA, Mo anode, using a 0.060 µm capillary lens. 120 seconds, He flush (1.7 l/min): strong signals for phosphorus and calcium). •฀PLM:฀in฀plain฀transmitted฀and฀polarized฀light,฀with฀a฀Zeiss฀Standard฀17฀ microscope, (mag. 200x): birefringence, polarization colours refractive indices. •฀X-ray฀diffraction฀(XRD):฀Siemens฀D8,฀GADDS฀(general฀area฀detection฀ diffraction system) instrument with CuKα radiation and with monocapillary optics; (2 Theta from 18.00º to 56.50º with 100 s step time) / XRD: with 57.3 mm Gandolfi cameras with CuKα radiation, voltage set at 40 kV, with current at 30 mA, exposure times varied from 1:30 to 5:30 h). •฀Scanning฀electron฀microscopy฀with฀energy฀dispersive฀X-ray฀spectrometer฀of฀ a small sample / cross-section (SEM-EDX, JSM5910LV: presence of calcium and phosphorus). •฀Fourier฀Transform฀Infrared฀–฀Attenuated฀Total฀Reflectance฀(FTIR-ATR)฀of฀ cross-section (Perkin Elmer Spectrum 100 FTIR Spectrometer, Spectrum Spotlight 400 FTIR Microscope, 16x1 pixel linear Mercury Cadium Telluride (MCT) array detector). •฀Sample฀for฀cross-section฀taken฀at฀lower฀left฀corner. Fig. 97 Cross section: 1. top layer, 2. bone-white layer, 3. paper Summary of Methods for Examination of the Drawing Arie Wallert, Birgit Reissland, Luc Megens An Eyckian Crucifixion Explored: Ten Essays on a Drawing 134 Summary of Methods for Examination of the Drawing 135 •฀Digital฀microscopy:฀(Hirox:฀KH-7700฀digital฀microscope฀with฀2.11฀megapixel฀ CCD sensor, res. max. 10,000 x 10,000 pixels, magnifications 350 - 2000x). Identification of Binding Medium for Bone-White Layer •฀With฀MCA:฀staining฀of฀the฀cross-section฀with฀acid฀Fuchsine฀(rosaniline฀ hydrochloride). •฀FTIR-ATR฀(Perkin฀Elmer฀Spectrum฀100฀FTIR฀Spectrometer,฀Spectrum฀ Spotlight 400 FTIR Microscope, 16x1 pixel linear Mercury Cadmium Telluride (MCT) array detector). Fig. 100 Distribution of gold particles (HIROX digital microscope) Fig. 98 Identification of a protein as a binding medium in the bone white layer (magenta colour, staining with Fuchsine), cross section Spot Identification of Goldpoint Line •฀With฀XRF:฀ARTAX฀μ-XRF฀spectrometer,฀50฀kV,฀600฀μA,฀Mo฀anode,฀using฀a฀ 0.060 µm capillary lens. 120 seconds, He flush (1.7 l/min): quantification FP, PyMca. Identification of Silverpoint Lines •฀With฀XRF:฀ARTAX฀μ-XRF฀spectrometer,฀50฀kV,฀600฀μA,฀Mo฀anode,฀using฀a฀ 0.060µm capillary lens. 120 seconds, He flush (1.7 l/min): quantification FP, PyMca. •฀Digital฀microscopy:฀(Hirox:฀KH-7700฀digital฀microscope฀with฀2.11฀megapixel฀ CCD sensor, res. max. 10,000 x 10,000 pixels, magnifications 350 - 2000x). Fig. 101 XRF spectrum silverpoint line Fig. 99 XRF spectrum goldpoint line An Eyckian Crucifixion Explored: Ten Essays on a Drawing 136 Summary of Methods for Examination of the Drawing 137 Distribution of Gold Point Lines •฀Analysis฀with฀macro฀XRF฀scanning฀(MA-XRF:฀Bruker฀M6฀Jetstream฀scanning฀ instrument. The surface of the entire drawing scanned in three cycles, excitation radiation of 35 kV and 500 µA from a Rh anode focused onto the 356 µm measuring spots with a monocapillary lens. Step size 350 µm with mechanical res. 267. Dwell time 50 ms. Elemental distribution maps created for Ag, Pb, Fe, K, Au and Ag). •฀Visualized฀with฀infrared฀reflectography฀(IRR:฀Osiris฀512฀x฀512฀infrared฀ camera with Rodagon 1:5.6 lens, f = 150 mm IR, equipped with a Hamamatsu (G11135-512DE), InGaAs image sensor allowing a 4096 x 4096 pixel capture area. Sensitivity in the NIR region to approx. 1700 nm. Visible light filtered off at 875nm by a Schott RG830 filter. Instrument fitted with dedicated f = 75 mm macro lens for close-up examinations). Identification of Indigo on the Back of the Drawing •฀With฀PLM:฀in฀plain฀transmitted฀and฀polarized฀light,฀with฀a฀Zeiss฀Standard฀17฀ microscope, (mag. 200x): isotropic, refractive indices. •฀MCA:฀reduction฀to฀leuco฀form฀with฀sodium฀dithionite. •฀Fibre฀optic฀reflectance฀spectroscopy฀(FORS:฀Avantes฀AvaSpec–2048฀ spectrometer, over range of 380 nm - 750 nm, illumination from Mikropak HFX-2000 xenon light source and AvaLight-Hal source). Iron Gall Ink Lines •฀With฀XRF:฀ARTAX฀μ-XRF฀spectrometer,฀50฀kV,฀600฀μA,฀Mo฀anode,฀using฀a฀ 0.060 µm capillary lens. 120 seconds, He flush (1.7 l/min). •฀Visualization฀by฀‘false฀colour฀infrared’฀imaging:฀IR฀photography฀in฀the฀850฀ nm – 1100 nm range with a Sony 848 digital camera with a Schneider BW infrared filter, cutting off at about 850 nm. IR image integrated in the VIS image by manipulation of the channels in Photoshop C5. •฀Ultraviolet฀Fluorescence฀(UVF)฀photographs:฀lines฀drawn฀in฀iron฀gall฀ink฀ showed the typical absorption under UV radiation and appeared darker. Fig. 102 UV fluorescence photo: the contour lines of the rock absorb UV radiation and appear darker Indentations with Iron Stylus •฀In฀raking฀light. •฀With฀XRF:฀ARTAX฀μ-XRF฀spectrometer,฀50฀kV,฀600฀μA,฀Mo฀anode,฀using฀a฀ 0.060 µm capillary lens. 120 seconds, He flush (1.7 l/min): quantification FP, PyMca. Identification of Protein and Starch as Two Top Layers •฀With฀PLM:฀UV฀and฀normal฀light:฀identification฀of฀2฀layers฀(each฀1฀μm฀thick). •฀MCA:฀staining฀of฀the฀cross-section฀(embedded฀in฀Polypol฀PS฀230฀resin฀ with Peroxan ME-SOL) with acid Fuchsine (rosaniline hydrochloride) and subsequent staining with iodine/potassium iodide solution (I/KI). •฀Pyrolysis฀gas฀chromatography/mass฀spectrometry฀using฀ tetramethylammonium hydroxide for thermally assisted hydrolysis and methylation (THM-Py-GC/MS) (Frontier labs 3030, Thermo Focus GC - ISQ mass spectrometer; 500°C, TMAH 2.5 %). •฀Raking฀light:฀determination฀of฀brush฀strokes. Fig. 103 Cross section: on top of the bone-white layer are two layers: the first layer is a protein (magenta, stained with Fuchsine), and the second layer consists of starch (black, staining with KJK) Fig. 104 Cross section (UV): 1. two top layers (blue fluorescence), 2. some dirt particles between top layers and bone white layer (dark), 3. Bone-white layer, 4. unidentified fluorescing layer, 5. paper support An Eyckian Crucifixion Explored: Ten Essays on a Drawing 138 Summary of Methods for Examination of the Drawing 139 Verso: Differentiation of Secondary Paper Layers The reconstruction of the layer structure of old repairs and mounting papers on the original verso is quite complex. Most of the paper has been removed and the original context has been lost. About nine different papers can be distinguished (in chronological order, oldest first): 1. Verso of the original paper with indigo powder 2. Complete historic lining with a laid paper showing the watermark P and the inscription: Huybreght van Eijck 3. Repair paper (vergé with clear lines) mending old paper damage 4. Paper (possibly the same as paper 3?), on old tear 5. Mounting paper (vellum?, nineteenth century?) 6. Blue paper (eighteenth or nineteenth century?) 7. Corner of strong paper (nineteenth century?) 8. Traces of paper on paper 7 9. Paper with inscription: Van Eik / Uitvinder van de Olijverf Adhesives between Secondary Paper Layers •฀MCA:฀staining฀of฀the฀cross-section฀(embedded฀in฀Polypol฀PS฀230฀resin฀ with Peroxan ME-SOL) with acid Fuchsine (rosaniline hydrochloride) and subsequent staining with iodine/potassium iodide solution (I/KI). •฀FTIR-ATR฀(Perkin฀Elmer฀Spectrum฀100฀FTIR฀Spectrometer,฀Spectrum฀ Spotlight 400 FTIR Microscope, 16x1 pixel linear Mercury Cadium Telluride (MCT) array detector). Fig. 105 Verso showing some nine different remains of mounting and repair papers as well as residues of brown coloured adhesive An Eyckian Crucifixion Explored: Ten Essays on a Drawing 140 Summary of Methods for Examination of the Drawing 141 Contents Foreword 4 Sjarel Ex Introduction 6 Friso Lammertse, Albert J. Elen 1 The Discovery 8 Friso Lammertse 2 Notes on the Material Aspects 24 Arie Wallert, Birgit Reissland, Luc Megens 3 Two Papers and a Watermark 36 Albert J. Elen 4 The Use of Goldpoint and Silverpoint in the Fifteenth Century 44 An Van Camp 5 Attribution, Style and Date 58 Fritz Koreny 6 Reflections, Models and Possible Function 70 Guido Messling 7 Copying and Beyond: the Multiple Functions of Early Netherlandish Drawings 80 Stephanie Buck 8 Some Eyckian Drawings and Miniatures in the Context of the Drawing 94 Till-Holger Borchert 9 The Drawing and Colour 108 Stephan Kemperdick 10 The Relationship Between the Rotterdam Drawing and the New York Painting 116 Maryan W. Ainsworth Summary of Methods for Examination of the Drawing 134 Notes 142 Bibliography 152 Biographies 158 museum van boijmans beuningen Contents An Eyckian Crucifixion Explored: Ten Essays on a Drawing 2 Contents 3