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The Restoration of the Panel Painting depicting the Adoration of Shepherds with a Saint Bishop

Three-dimensional reintegration of missing elements by 3D printing
Claudia Cricchio

Abstracts

This paper presents the restoration of a panel painting with frame of the second half of the XVI century and now preserved at the Abatellis (i.e. Galleria Regionale della Sicilia di Palazzo Abatellis, Palermo, Italy). A careful historical and artistic study as well as a diagnostic analysis preceded the restoration that aimed to re-establish a good reading of the painting. The essay focuses on the possibility to reintegrate a missing element of the frame with materials used in the 3D printing, in order to restore its function of “spatial connection” between the painting and the expositive environment. The result of the experimentation was the design of two elements, printed using reverse engineering and a 3D printer, after testing three types of filaments.

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Historical and artistic information

1The whole restoration was accompanied by a careful historical and artistic analysis that permitted to collect information about the painting (Fig. 1).

Fig. 1 The Adoration of shepherds with a Saint bishop

Fig. 1 The Adoration of shepherds with a Saint bishop

The painting before the restoration: a) recto; b) verso.

Credits: © Claudia Cricchio 2017

2It represents “The Adoration of shepherds with a saint bishop” by an unknown author of the second half of the 16th century. In a concise way (similar to the engraving style), the painter depicted few figures in a scenario in which ruins and a wooden shed are visible. In the central part of the scene, the Holy Family is represented with the ox, the donkey and two shepherds observing the Child. The other spectators are a shepherd and a bishop, respectively represented on the left and on the right of the central figures, while a group of three angels are observing the scene from a cloud. On a second level other two shepherds are receiving the message of the Christ birth.

3Analysing some archive documents, the original expositive place was discovered: the painting came from the ancient Benedictine abbey of San Martino delle Scale [Meli 1870]. The examination of a catalogue written by Giuseppe Meli during the transportation of some artefacts from the abbey to the current Museo archeologico Antonino Salinas [Meli 1873; Abbate 1989] revealed the production by an unknown Sicilian painter of the second half of the 16th century [Meli 1870].

4The iconology choices (such as the background), the elongated figures and the vibrant colours would confirm the painter’s belonging to the Mannerism. Comparisons with other painters operating in Sicily in the same period highlighted analogies with Giovanni Paolo Fonduli, especially in the firm drapery description and the bright colours [Pugliatti 2011].

Executive techniques

Support

5The examined painting has a landscape rectangular shape (108,5 x 85 cm x 4,5 cm thickness) and it is composed of two horizontal planks, assembled with a tenon and mortise joint (probably glued with calcium caseinate) [Cennini 2003]. The tangential cutting and the presence of knots reveal that the chosen constitutive material was not so refined. On the painting verso two crossbars are anchored to the support with handmade nails, inserted from the verso. They have the function to maintain the painting planar, reducing warps induced by thermo-hygrometric variations and influenced by the kind of wood cut, defects in the grain and the interactions with the overlying layers. The wooden species identification, performed by means of transmitted light optical microscopy and according to identification keys available in wood anatomy literature [Nardi Berti, 2006, Schweingruber, 1990], was arduous because of the poor conservative conditions of samples taken from the support and the crossbars. The observation of anatomical features indicates that probably silver fir (Abies sp.) wood was used.

Ground, painted film and varnish

  • 1 Analysis perfomed by means of a Shimatsu FTIR 8000 on a sample prepared by mixing around 2mg of sam (...)
  • 2 Analysis perfomed by means of a BWTek i-Raman Plus (785nm) by La.Ma.R.C.
  • 3 Analysis perfomed by means of the portable instrument CPS100 by CRPR (Centro per la Progettazione e (...)
  • 4 Analysis perfomed by means of the portable instrument CPS100 (750-1150nm) by CRPR.

6The whole wooden surface (excluding the edges, verso and the crossbars) is covered by a gesso layer composed by animal glue and gypsum, whose components were identified by FTIR analysis1. On this layer a preparatory drawing was identified consisting of a dark pigment probably diluted in water and applied by brush. Observing the painting in raking light, the figures also appear delimited by incisions. According to the 15th and 16th century practices, the technique used by the painter could be identified with the so called mix technique, consisting of tempera covered by oil-resinous glazing: the latter was generally used to confer a higher sense of transparency and depth to painting [Maltese 1973]. Raman spectroscopy was performed by means of a portable instrument2 on several points of different colours. Comparing the Raman Spectroscopy results with the False colour infrared photography3 ones, part of the palette used by painter was reconstructed. Particularly the use of two different pigments of the same colour was highlighted both for red and blue. Red colours consist of cinnabar and minium for characters’ skin tone and lips, shepherd’s dress (behind Saint Joseph) and Virgin’s dress. Azurite and indigo were found mixed in the sky. The Infrared photography4 allowed a more detailed reading of painting, highlighting a final glazing.

Frame

7A rectangular “a cassetta” frame [Sabatelli, Zambrano and Colle 1992] enhances the painting. It consists of four wooden planks assembled with mitre joints, by means of artisan nails and probably animal glue. The four angles present a sculpted phytomorphic decorations and probably they were anchored to the wooden structure by nails.

8Nowadays the frame is covered by a varnished silver gilt, whose orange fluorescence was observed by a UV lamp. The gilt was made applying the silver leaves on a red bole clay; probably, gypsum and animal glue were used for the frame ground layer. The visual analysis of the superior right angle permitted to speculate that, probably, the original colour of the frame was black: it was observed also in other little areas not covered by gilded layer. Moreover a perimetral overhanging traces of ground and bole were observed on the painting. These details suggested that probably the gilt was the result of a later intervention.

9Again the identification of constitutive wooden species was hard due to the poor conservative condition, the microscopic observation suggests the use of silver fir even for the frame.

Condition assessment and Restoration History

10A considerable layer of incoherent dirt covered the whole painting and largely the sculpted parts and the upper edge of the frame.

11The support looked structurally weakened and full of boredust due to a past attack by insects. They belong to Anobidae family, probably Anobium Punctatum, as identified by professor Giovanni Liotta who examined the boredust and a pupal cell [Liotta 1994]. Holes and galleries were evident on the recto, edges and verso (Fig.2a).

12The painting underwent severe thermo-hygrometric variations during its life that, coupled with the plain sawn and the presence of knots and other defects, resulted in a slightly cup of the constitutive planks, two large shrinkage cracks in the upper board and a disjoint between the boards [Ciatti et al. 2012]. These alteration caused a large amounts of ground and painted layer lacunae. A significant area was abraded, perhaps because of a previous and improper intervention, which caused the loss of material in the Virgin’s dress (Fig.2b). Probably it had to be blue: indeed the analysis by means of digital microscope permitted to identify a blue area beyond the brown layer (probably related to a lacquer alteration).

Fig. 2 State of preservation of the painting

Fig. 2 State of preservation of the painting

a) Signs of insects attack; b) abrasions in the Virgin’s dress observed by a digital microscopy (200x); c) oxidised varnish; d) missing frame angle.

Credits: © Claudia Cricchio 2017

13Surface texture and deteriorations were observed in raking light. An examination of the ground’s and painted layers’ craquelure was conducted more accurately: this phenomenon was probably caused by support dimensional variations and shifted to the upper layers, giving rise to delamination and inter-layer delamination phenomena. Moreover the presence of too long nails caused local deformations of the painting layers.

14Many repainted areas covered the painting (Fig.3): they appeared more evident in UV fluorescence.

Fig. 3 Repainted areas

Fig. 3 Repainted areas

Saint bishop’s head observed in a) incidence light; b) UV; c) grazing light.

Credits: © Claudia Cricchio 2017

15Two samples were taken from a repainted area above the Saint Bishop crosier with different purposes: ADP01 was used to prepare a polished section analysed in Reflected light microscopy, revealing the presence of an oil repainted layer on a dark ground composed by coarse aggregates (Fig.4); ADP02 was a small fragment that underwent FTIR spectroscopy leading to the identification of an oil as binder.

Fig. 4 Analyses of repainted areas

Fig. 4 Analyses of repainted areas

a) FTIR spectrum of the sample ADP02; b).stratigraphic section observed by a reflected light optical microscopy.

Credits: © Bartolomeo Megna 2017

16An uneven varnish was observed in visible light: it was so much oxidised to hinder a proper interpretation of the figures (Fig.2c). Raman spectroscopy detected the presence of lead-based pigment in several areas corresponding to different colours. This fact would suggest that the pigment is not related to the painted film, but to the protective one: it could have been used to accelerate the polymerization process and to simulate an older protective layer [Cennini 2003].

17Considering the frame, some lacunae of the ground were visible as well as abrasions and oxidation of the silver leaves. Some cracks were evident on ground and finishing layers, probably caused by natural movements of wood as the gypsum layer cannot follow the wood deformation due to RH fluctuations and it results in a failure of the ground layer [Łukomski, 2012]. An element of the superior right angle is missing (Fig.2d). Finally on the verso some puttying is visible on the knots.

Restoration

18The restoration intervention was conducted in the room X of the Abatellis and it had the purpose to re-establish a correct reading of the painting. The first operation was the mechanical removal of surface dirt by brush and poli-styrene-butadiene sponge (Wishab® 4101 soft- Akapad).

19A permethrin-based (Xylores® pronto antitarlo– Antares) insecticide was applied by means of brush and syringe, taking advantages of the holes made by insects, as a preventive treatment of the support as no evidences of occurring attack were found. In order to reduce the evaporation a polyethylene packaging wrapped the painting for fifteen days.

20A slight consolidation of the wooden structure with an acrylic resin (Paraloid® B72- CTS) in acetone was considered mandatory because of the massive insects attack. As the structural conditions were not so severe the concentration of acrylic solution was maintened low ranging from 3% at the beginning to 5% at the end of the treatment. After general consolidation a vinylic adhesive(Bindan-P®, Bindulin – AN.T.A.RES) was applied inside the cracked wooden parts by means of a metal spatula and its adhesion was increased using clamps, while the delaminated frame wood fragments were stuck together with a thermoplastic poly ethyl oxazole-based adhesive (Aquazol 500®- CTS).

  • 5 The set consists of solvents like ligroin, acetone and ethanol used pure or mixed together with dif (...)

21The painting layers were consolidated too. In order to verify the hydrophilicity of the surface a drop of water was applied on the painting and observed to qualitatively determine contact angle; the measure was repeated in several points of the painting and highlighted its weak hydrophilic nature. A little agarose gel disk was placed on the painted surface in order to measure the pH with a skin pH meter: registered value was 5.0. Then the painted surface was tested with a set of neutral organic solvents, the Wolbers-Cremonesi mixtures5: it confirmed the polar nature of the surface [Cremonesi and Signorini 2012]. During the whole intervention, the support responsiveness to relative humidity fluctuations was verified, checking the distance between the two boards by means of calibre. All these tests lead to the choice of poly ethyl oxazole-based adhesive (Aquazol 200®- CTS), dissolved to 5% in deionized water as consolidant for the delaminated painted film applied by syringe: its penetration was increased by means of a thermocautery interposing a heat-resistant transparent polyester film (Melinex®- AN.T.A.RES) between the instrument and the surface.

22After consolidation was finished cleaning phase started. The first step was the removal of the superficial coherent dirt, applying an gelified oily emulsion consisting of ligroin and a buffered solution with pH 5.0: it was applied using a brush for a minute and removed first of all with a dry swab and then with one soaked of ligroin. Simultaneously the frame was cleaned with an oily emulsion.

23The aim of the second cleaning step was the removal of the oxidised varnish thinner testing the previously described oily emulsion and a set of buffered solutions prepared at pH of 5.5, 7.0, 8.5 and 9.5. Every set included:

  • simple buffered solution

  • buffered solution with non-ionic water–soluble cellulose (hydroxypropylcellulose)( Klucel G®- CTS)

  • buffered solution with citric acid

  • buffered solution with tetra sodium EDTA

  • buffered solution with neutral pH non-ionic surfactant (Tween 20®- CTS)

  • buffered solution with sodium lauryl sulphate [Cremonesi and Signorini 2012].

  • 6 60% of ligroin and 40% of ethanol.
  • 7 80% of ligroin and 20% of ethanol.

24The best results were obtained with some mixtures made of ligroin and ethanol. In order to reduce the interaction with the surface, too abraded, a mixture of LE46 in form of Solvent Surfanctant Gel was used. It was worked for a minute, then removed with a dry swab and a LE27 soaked one (Fig.5). The black background (probably repainted) seemed sensitive to this system, thus the gel was not used there. The LE4 Solvent Surfanctant Gel was also useful to remove some repainted layer. Drips and perimetral bole were definitively removed by means of a scalpel after the application of a gel made of 2% gellan in water.

Fig. 5 Cleaning phases

Fig. 5 Cleaning phases

Virgin’s face a) before the cleaning phase; b) after the first step of the cleaning phase; c) during the second step of the cleaning phase; d) after the second step of the cleaning phase.

Credits: © Claudia Cricchio 2017

  • 8 Silver fir used was previously treated with biocide and acclimated in the working room for seven mo (...)

25Preliminarly to support consolidation the painted film was protected using a urea-aldehyde resin-based varnish (Laropal ®A-81- CTS): when the varnish dried, the cracked parts were temporary protected with Japanese paper stripes, applied with cyclododecane in White Spirit at 80%. The disjoint between boards and the large cracks in the upper board were treated by inserting silver fir wedges8, as it’s the wooden species of the support, glued inside them with a vinylic adhesive(Bindan-P®, Bindulin – AN.T.A.RES ), chosen for its elasticity. The excess of the wooden wedges were removed and then sanded.

26Metal elements were treated with an anti-corrosion product (Fertsab- Bresciani Srl). Central disjunction and cracked wooden parts were filled with a pigmented bi-component epoxide puttying; while the ground lacunae were filled with a Bologna gypsum and rabbit glue-based putty, polished with scalpel and sandpaper.

27The next phase consisted in retouching purposing to re-establish the painting readability: first of all the abraded areas were retouched with watercolours and varnish colours (Fig.6); particularly the smaller puttying were retouched mimetically, while the larger one using distinguishable techniques: hatching for the painted layer and speckling for the sculpted frame. The colours used were watercolours and, after a layer of the varnish previously used, varnish colours.

Fig. 6: Retouching phase

Fig. 6: Retouching phase

Virgin’s face a) before the retouching phase; b) after the retouching phase.

Credits: © Claudia Cricchio 2017

  • 9 Produced by Kremer.

28Finally, a chromatic balancing of the wedge used on the verso and a last varnishing using a 20 % of an aliphatic resin (Regalrez 1094- CTS ) dissolved in Shellsol ®D409, added of stabiliser(Tinuvin®292- AN.T.A.RES) (2%) and an elastomer (Kraton®G1650- CTS.) (3%), were used.

Experimental study

29The following report was conceived from the necessity of re-establishing the frame completeness, restoring its function of “spatial connection” between the public and the expositive environment, as suggested by Cesare Brandi [Brandi 2000]. The study proposes a reverse engineering and 3D printing methodology to produce a reproduction of the missing element that could be considered alternative to cast operation or insertion of brand new carved wooden elements, guaranteeing a higher reproduction accuracy.

30Casting is generally banned in Italy and its use is regulated by Ministerial Decree April 20, 2015; when the operation is accepted, the application of silicon rubber could imply chemical (because part of the constitutive materials can be absorbed by the surface) and physical mechanical detriments (particularly risky if the surface is weakened as in the examined case) [Tosini 1999]. As a matter of fact, carving operation involves the search for seasoned woods with thermo-hygrometric features similar to the original one and implies a high risk of interpretation by the carver. Finally the use of reverse engineering allows the availability of a model that can be printed over and over again with the same result, giving the opportunity to produce several identic pieces if necessary.

  • 10 https://en.wikipedia.org/w/index.php?title=Reverse_engineering&oldid=811747899
  • 11 A set of data points in a three-dimensional coordinate system (x,y and z).
  • 12 A collection of vertices, edges and faces that determine the shape of a polyhedral object in 3D com (...)

31Reverse engineering “consists in a process of extracting knowledge or design information from a product and reproducing it or reproducing anything based on the extracted information” 10. Among the several current systems, a structured light 3D scanner was used: it takes advantages of precise and fixed patterns of light in order to capture geometrical data from a real object, without touching it. The acquired data are processed in a point cloud11, then convert into a mesh12.

32The obtained mesh allows to print the object by 3D printers. There are many kind of devices that use different printing techniques, but probably the most used one is the FDM (Fused Deposition Modeling) technology: it consists in printing objects using thermoplastic materials (filaments or pellets) that are extruded in overlapping layers [Gibson, Rosen and Stucker 2015]. These new technologies have been often used in the conservation and restoration field in order to digitalise artefacts [Sher 2013; Alberghina et al. 2017] and recreate a copy, to design packaging structures [Asla et al. 2012] and reproduce missing elements [Bigliardi et. al. 2015].

33In our case we used the FDM printing to produce two elements: one intending to reproduce the frame stratigraphy and the other proposing the wooden frame colour. These elements are applied on the frame by means of magnets so that they can be easily exchanged, ensuring a not invasive connection to the artwork. Preparing two different substitutive elements was intended to show the potential of such technique in creating a more interacting experience for visitors.

Filaments selection

34Three different filaments produced by the Dutch society Formfutura were chosen:

    • 13 Technical sheets available on Formfutura website.

    two EasyWood™ filaments (ø 1.75 mm): the main characteristic of these filaments is the presence of a 40% of pulverized cellulosic particles dispersed in a slightly modified PLA(polylactic acid). Among the several colours of this products category, the EasyWood ™ Pine and the EasyWood™ Coconut 13were picked: the latter is described as a less responsive to humidity material and characterised by a low shrinkage and deformation values; the first one was selected for its light dye.

    • 14 Technical sheets available on Formfutura website.

    ApolloX™(ø 1.75 mm)14: consists of a modified mixture of ASA, acrylonitrile styrene acrylate. It is an opaque whitish amorphous polymer, belonging to the styrene class. It is produced from the addition of an elastomer during the copolymerization between styrene and acrylonitrile polymers. It’s proposed as a climatic and heat variations, UV and impacts resistant material, with colour stability: all these characteristics allow outdoor exposition. All these peculiarities motivated the choice of this material. A white filament was selected in order to easy the retouching phase.

Printing phase

35It consisted in preparing 78 5x2x0.2 cm samples: 72 addressed to an accelerated ageing and 6 to retouching test. They were developed by a CAD software, successively converted into .stl format and submitted to the slicing step using the freeware Cura. After generating a G-code, the printing was launched by means of a FDM machine (MakerBot The Replicator 2).

Samples preparation and artificial ageing

36As the substitutive elements are not directly connected to the original frame nor painting support, the investigation on compatibility is limited to the coupling of 3D printing materials and traditional ground layers to be applied on them and it’s not extended to compatibility between wood and the 3D printing materials.

37In order to test the compatibility between different traditional and synthetic ground layers and the previously described filaments, several different samples were prepared and named using the first letter in Italian of the constitutive materials:

  • the first ones stand for the support names (A= ApolloX™; C= EasyWood™ Coconut; P= EasyWood ™ Pine)

  • the second ones are the abbreviations for the adhesive (C= rabbit glue; P= Plextol® B500)

  • the third and the fourth ones stand for the aggregates (G= gypsum; C= calcium carbonate).

38E.G. APGC indicates a sample consisting of ApolloX support with ground composed of mixed Gypsum and Calcium Carbonate aggregates binded with Plextol, while PCC indicates a sample consisting of Easywood Pine with ground composed by Calcium Carbonate and rabbit glue.

39Six samples were prepared for each combination following the scheme below (fig.7).

Fig. 7 Table 1

Fig. 7 Table 1

Scheme for the preparation of the samples.

Credits: © Claudia Cricchio 2017

40Since the adhesive used were water-based, a preliminary test on samples was conducted for verifying the water and rabbit glue absorption: it revealed the water-repellent behaviour of ApolloX™. Once the ground layer was dry, it was sanded to obtain a smooth surface.

41The samples underwent three different kind of physico-chemical stress for 1320 hours designed to induce chemical and mechanical stresses in order to observe incipient cracks or other alteration forms:

  • alternated exposition every 8 hours to UV and dark inside a QUV machine (40°C) to induce oxidation or other UV inducted alteration to the surface;

  • humidity variations at constant temperature, RT, moving the samples from a hermetic heat-resistant box containing water to another containing silica gel to verify the stability of the samples with respect to relative humidity fluctuations;

  • temperature variations between -18 and around 20 °C every 8 hours, inside hermetic heat-resistant boxes to induces mechanical stresses related to temperature variations.

42Two samples of each combination of filament and ground layer and specifically the samples 1 and 2 underwent to QUV machine, 3 and 4 to temperature variations lastly 5 and 6 to humidity variations. The ageing was documented, scanning the samples and observing them with a Leica MS5 microscope equipped with a Leica M170HD camera: it allowed noting the emerging alteration phenomena about every day that were reported in the table presented in Fig. 8.

Fig. 8 Examples of alterations produced by accelerated ageing

Fig. 8 Examples of alterations produced by accelerated ageing

a) discolouration caused by QUV ageing; b) deformation caused by temperature variations; c) ground detachment from support caused by humidity variations.

Credits: © Claudia Cricchio 2017

Retouching colours test

43A coating and absorption test was executed in order to produce an element with a colour similar to the wooden frame dye: the EasyWood™ Coconut filament was excluded because its colour was considered too dark. For this kind of test six samples were used and prepared as follow (Fig 9.).

Fig. 9: Table 2

Fig. 9: Table 2

Scheme for the retouching test on printed samples.

Credits: © Claudia Cricchio 2017

44During the test, the following remarks were made:

  • on PC1, a homogeneous coating was reached tamponing the surface by absorbent paper;

  • on AC1, tamponing the surface by absorbent paper and PVA sponge do not permitted a homogeneous coating;

  • sanding the surface of sample PC2, PC3, AC2 and AC3 improved the coating: only on PC1 and PC2 a more homogeneous coating could be obtained even without tamponing (Fig.10).

Fig. 10 Experimental study

Fig. 10 Experimental study

Printed samples used for the retouching phase.

Credits: © Claudia Cricchio 2017

Conclusions

45The results obtained with the accelerated ageing and the retouching colours addressed the choice on the EasyWood™ Pine filament. Indeed, it could be considered the most compatible material with the traditional ground layers, because in any case a ground delamination from the support was noticed after ageing. The selection was confirmed even if it revealed itself responsive to thermo-hygrometric variations, because the thermo-hygrometric conditions of the storage (where the painting will be stored) are stationary. Moreover the finishing test highlighted that the appearance of the thermoplastic material can be improved polishing the surface by sandpaper. In the examined case, EasyWood™ Pine represents the best compromise between aesthetic aspect and resistance to physico-chemical stress.

Models design and printing

  • 15 Artec 3D Scanner Spider.

46Simultaneously, a study on modelling of missing frame angle was conducted. After puttying operation on the frame, the scanning of the angle with the missing element and the less damaged one was planned: a structured-light 3D scanner15 with a high accuracy and without any contact with the artefact was used. Points clouds were acquired, removing the external points from the scanned object and creating two meshes. The final angle 3D model was obtained with a subtraction operation starting from the superimposition and alignment of a mesh on the other (Fig.11). A parallelepiped, provided with holes useful for housing three small neodymium magnets, was added to the final mesh in order to place the printed element in the frame cavity.

Fig. 11 Frame acquisition by portable scanner

Fig. 11 Frame acquisition by portable scanner

Alignment between the two meshes.

Credits: © Francesco Di Paola 2017

Finishing choices and placement of printed elements

47The last printing set up allowed producing two identical elements whose edges were polished by means of carpentry tools, in order to conform them to the frame cavity: it highlighted the good workability of EasyWood™ Pine. The two printed elements were worked differently: on the first one, the frame stratigraphy was re-proposed, while on the second one the wood colour of the frame was achieved using retouching colours. In both cases, the staircase effect was reduced by means of a thermocautery at 250 °C and sanding the surface. A hole originated from the removing of an old nail was used for screwing a metal plate in the frame cavity: it permitted to place the elements in reversible way using the small neodymium magnets placed in the 3D printed elements.

Final considerations

48In this work reverse engineering and 3D printing were used to integrate a missing element in a 16th century gilded frame. These techniques have been chosen instead of traditional carving or casting as they can ensure a more accurate reproduction of the missing parts based on the similar present elements, without touching the delicate original frame as requested by casting and avoiding risk of interpretation involved with wood carving.

49An experimental study has been performed to verify the compatibility between suitable 3D printing materials and traditional and modern ground layers.

50The central purpose of the research was a respectful actualization of the main restoration principles (i.e. distinguishability, reversibility and compatibility), as the proposed integration method for missing repetitive parts can ensure a safe, contactless, not interpretative reproduction. Moreover the 3D printing allows the reproduction of several identical elements designed to vehicle different information on the restored artwork, as shown by the two different printed pieces proposed in this work. This integration method offers the opportunity of enhancing one of famous Brandi statement: “Restoration is the methodological moment of recognition of the work of art, both in its physical composition and in its aesthetic and historical bipolarity, before being transmitted into the future” [Brandi 2000:6].

51The information derived from the experimental study were surely essential: it highlighted the Easywood Pine responsiveness to high relative humidity conditions. Therefore a conservative place climatic monitoring is recommended.

52A more detailed study about the thermoplastic materials composition and physic-chemical behaviour could be guide towards a discovery of new materials useful for restoration field. Finally it could be useful verifying the constituents of thermoplastic materials commercialised as pellets, whose composition could be make adaptable to specific necessities.

53The results of this experimental study are a starting point about the use of 3D printing materials in the restoration field and have to be intended as an initial phase of a more complex project. (Fig.12)

Fig. 12 The painting after the intervention

Fig. 12 The painting after the intervention

Painting with a) the wooden coloured angle; b) the angle illustrating the frame stratigraphy.

Credits: © Claudia Cricchio 2017

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Notes

1 Analysis perfomed by means of a Shimatsu FTIR 8000 on a sample prepared by mixing around 2mg of sample with 100mg of KBr, by La.Ma.R.C. (Laboratory of Materials for Restoration and Conservation), Università di Palermo.

2 Analysis perfomed by means of a BWTek i-Raman Plus (785nm) by La.Ma.R.C.

3 Analysis perfomed by means of the portable instrument CPS100 by CRPR (Centro per la Progettazione ed il Restauro) of Palermo.

4 Analysis perfomed by means of the portable instrument CPS100 (750-1150nm) by CRPR.

5 The set consists of solvents like ligroin, acetone and ethanol used pure or mixed together with different proportions.

6 60% of ligroin and 40% of ethanol.

7 80% of ligroin and 20% of ethanol.

8 Silver fir used was previously treated with biocide and acclimated in the working room for seven months.

9 Produced by Kremer.

10 https://en.wikipedia.org/w/index.php?title=Reverse_engineering&oldid=811747899

11 A set of data points in a three-dimensional coordinate system (x,y and z).

12 A collection of vertices, edges and faces that determine the shape of a polyhedral object in 3D computer graphics and solid modelling.

13 Technical sheets available on Formfutura website.

14 Technical sheets available on Formfutura website.

15 Artec 3D Scanner Spider.

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List of illustrations

Title Fig. 1 The Adoration of shepherds with a Saint bishop
Caption The painting before the restoration: a) recto; b) verso.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-1.jpg
File image/jpeg, 688k
Title Fig. 2 State of preservation of the painting
Caption a) Signs of insects attack; b) abrasions in the Virgin’s dress observed by a digital microscopy (200x); c) oxidised varnish; d) missing frame angle.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-2.jpg
File image/jpeg, 208k
Title Fig. 3 Repainted areas
Caption Saint bishop’s head observed in a) incidence light; b) UV; c) grazing light.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-3.jpg
File image/jpeg, 372k
Title Fig. 4 Analyses of repainted areas
Caption a) FTIR spectrum of the sample ADP02; b).stratigraphic section observed by a reflected light optical microscopy.
Credits Credits: © Bartolomeo Megna 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-4.jpg
File image/jpeg, 296k
Title Fig. 5 Cleaning phases
Caption Virgin’s face a) before the cleaning phase; b) after the first step of the cleaning phase; c) during the second step of the cleaning phase; d) after the second step of the cleaning phase.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-5.jpg
File image/jpeg, 856k
Title Fig. 6: Retouching phase
Caption Virgin’s face a) before the retouching phase; b) after the retouching phase.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-6.jpg
File image/jpeg, 648k
Title Fig. 7 Table 1
Caption Scheme for the preparation of the samples.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-7.jpg
File image/jpeg, 496k
Title Fig. 8 Examples of alterations produced by accelerated ageing
Caption a) discolouration caused by QUV ageing; b) deformation caused by temperature variations; c) ground detachment from support caused by humidity variations.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-8.jpg
File image/jpeg, 256k
Title Fig. 9: Table 2
Caption Scheme for the retouching test on printed samples.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-9.jpg
File image/jpeg, 508k
Title Fig. 10 Experimental study
Caption Printed samples used for the retouching phase.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-10.jpg
File image/jpeg, 156k
Title Fig. 11 Frame acquisition by portable scanner
Caption Alignment between the two meshes.
Credits Credits: © Francesco Di Paola 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-11.jpg
File image/jpeg, 316k
Title Fig. 12 The painting after the intervention
Caption Painting with a) the wooden coloured angle; b) the angle illustrating the frame stratigraphy.
Credits Credits: © Claudia Cricchio 2017
URL http://journals.openedition.org/ceroart/docannexe/image/5224/img-12.jpg
File image/jpeg, 704k
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References

Electronic reference

Claudia Cricchio, « The Restoration of the Panel Painting depicting the Adoration of Shepherds with a Saint Bishop », CeROArt [Online], EGG 6 | 2017, Online since 18 May 2018, connection on 19 October 2018. URL : http://journals.openedition.org/ceroart/5224

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About the author

Claudia Cricchio

Claudia Cricchio graduated in 2017 in Conservation and Restoration of Cultural Heritage at the University of Palermo, specializing in painted artefacts on wood and canvas, wooden sculpted artefacts, structures and furniture, assembled and synthetic painted artefacts. After the graduation, she participated to the annual conference of IGIIC 2017, competing for the prize “Best thesis”. She was selected by Fondazione Cologni, obtaining an internship contract with a laboratory settled in Palermo.

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Copyright

Licence Creative Commons
CeROArt – Conservation, exposition, restauration d'objets d'arts est mis à disposition selon les termes de la licence Creative Commons Attribution - Pas d'Utilisation Commerciale - Pas de Modification 4.0 International.

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