AIC's 42nd Annual Meeting

Conservators will present tips and techniques that they have discovered, invented, and found handy, in a casual, conversational "open mic" format. Many will have pre-arranged tips with projected digital images, while all are welcome to spontaneously offer a tip verbally from the microphone the day of the session. The PSG will have a raffle for various prizes donated by vendors in the Exhibit Hall; this year, we have an Optivisor from Museum Services Corporation, a set of historical pigments from Sinopia, and Caselli spatulas from Talas, among others! Any tip-giver receives extra raffle tickets per tip presented, increasing the chances for winning these great prizes. It's always fun and useful at the PSG tips session, come participate on Thursday at 1pm.

Some cracks and small distortions that disrupt a paint film cannot be categorized as threats to the health and stability of the entire piece, yet they can have a profound influence on our aesthetic appreciation of the artwork, particularly in abstract paintings where the subtlety of the surface is the artistry. There is little in the literature about the treatment of these small but prevalent irritations, yet in my experience during 20 years of private practice treating Contemporary paintings, it is clear that they represent a disproportionate source of anguish for artists, viewers and owners.

The talk will consist of three parts:

1. A brief look at the history of treating cracks by lining or other means, whether such treatments were successful, and how they have shaped subsequent treatments.




2. A very practical demonstration of a method for treating cracks in paint films that we have been practicing in our studio for some time, including a discussion of the chemical and physical changes wrought by the treatment, our successes and failures, and what can be learned from those. This part of the talk is an expansion of a paper given in London in 2006 (see below for link to the paper), detailing several new variations adapted to different paint surfaces and types.




3. Some observations on our tolerance of damage, and how that varies with the age and type of object under consideration.

Pencil marks present a great challenge to removal when applied, purposefully or otherwise, to textiles such as unprimed cotton canvas. This problem is relevant to textile conservation as well as the conservation of contemporary paintings, where unprimed canvas is frequently left exposed, such as in the works of Morris Louis, Robert Goodnough, and Kenneth Noland. Errant, accidental marks and those applied intentionally as acts of vandalism are equally problematic. Pencils are generally comprised of low quality amorphous graphite, an electrically conductive semi-metal allotrope of carbon, pressed together with clay. When used to write, the powdered crystalline flakes of graphite break off; when this occurs on canvas, these powdery flakes become entrapped in the fiber and thread bundles, and are difficult to remove without compromising the structure of the fabric. Methods of safe removal were tested including laser ablation, mechanical removal methods, and reversed microemulsion cleaning agents including siloxane systems. The effectiveness of the method of removal was determined by visual results, the hand of the fabric, and microscopic examination to check for fiber damage and discoloration. Mechanical removal proved ineffective and impractical, and an appropriate microemulsion system could not be found that would not compromise both the aesthetic and the hand of the canvas. Successful results were only obtained with laser ablation at 532 nm; other wavelengths tested (266 nm, 355 nm, and 1064 nm) did not give satisfactory results. Ageing tests on the ablated canvas samples are forthcoming.

During the course of writing two books on American painters’ techniques, the authors have compiled and interpreted first-hand descriptions of techniques from artists’ notebooks, painting manuals, periodicals, suppliers’ catalogues, letters, diaries, and interviews. This talk focuses on the diversity of methods used during the period 1860-1910, when increased numbers of Americans traveled to various parts of Europe for instruction, resulting in an explosion of transplanted techniques. The influence of French teachers was especially strong; painting over brown underlayers, as Thomas Couture advocated, sometimes produced problems when paint became more transparent over time. A British handbook on technique that was edited for an American audience by Susan N. Carter reflects the influence of Couture on Americans and the diversity of approaches toward adding media at this time, as well as giving insights into Americans’ special relationship with the pigment chrome yellow. The painter Elizabeth Boott wrote letters that shed light on techniques used in Couture’s studio and in William Morris Hunt’s classes in Boston, as well on Frank Duveneck’s practice, in Munich, of adding medium copiously and applying extremely glossy varnishes. Hunt and his pupil Helen Knowlton were important as teachers and authors; Hunt’s comments on the darkening of the works of William Page were perceptive, but both Hunt and Knowlton reflected the growing unfashionability of caring too much about technique as the century neared its end. Other trends of this period include changing views on the aging of paintings, and a growing love of varying techniques simply for the sake of variation.

Some of the earliest artists’ advice columns, published under the editorship of Montague Marks in the magazine Art Amateur during the 1880s and 1890s, are useful in providing details of techniques at that time. These columns document, for instance, Thomas Dewing’s use of extremely thin, matte varnishes; the growing popularity of the shellac-based Soehnée’s varnish as both a retouching and a final varnish; and the surprisingly early beginnings of the tempera revival in America. Another important, little-known source is a series of interviews by DeWitt McClellan Lockman, who asked his fellow painters the kinds of detailed technical questions about topics like varnishing, pigments, and added media that tell conservators (for once!) what we really wanted to know. The Lockman interviews give insights into many topics, including changing varnishing practices and evolving ideas about adding medium, the increasing use of kerosene and other petroleum-derived solvents, and the growing influence of the controversial French author J. G. Vibert, whose many idiosyncratic theories included a preference for petroleum solvents and for zinc white over white lead. Albert Abendschein is an author who is still little known, but who had an influence on painters of the Ashcan school among others. His 1906 book documents many trends of this period, including the growing tempera revival and experiments with wax that spilled over from murals to easel painting; wax and commercially-produced paints containing wax and/or non-drying petroleum fractions were used by a number of American painters around the turn of the century.

This paper will present a summary of some of the varying materials employed in the creation of Spanish colonial paintings, including support systems, image media (such as cochineal and shell inlay), and surface coatings (related to European and American paintings from comparable time periods); and will discuss possible overlap of condition issues and treatment options with other painted objects.  The poor state of condition these paintings are often in will be reviewed, and examples of the examination and treatment of specific paintings presented.  Finally, a suggestion of how the treatment of Spanish colonial paintings may apply to the present field of conservation in general will be offered.

The Paintings Conservation Laboratory of the National Center for Conservation and Restoration (CNCR) was requested to restore part of a collection of paintings belonging to the Museo O’Higginiano y de Bellas Artes, from Talca, a city in the center-south of Chile. The interesting thing was that all of them were oil paintings on metal support. This was the first time the Paintings Conservation Lab had to face the intervention of objects of this kind, so the conservation and restoration of these paintings became the opportunity to learn about an unknown topic, and also to face the challenge of performing the appropriate treatments to ensure the future existence of these works of art.

These paintings were bought in Europe by the end of the XIX century, and later donated to Talca’s Museum. Three of them are medium sized (62 x 78 cm. aprox) and the other two are smaller (25 x 19 cm. aprox). It is believed that at least three of them are Flemish paintings, since one is signed by Flemish artist Willem Van Herp (XVII century), and there is another one with very similar characteristics but not signed, while a third one is different in iconography, but similar in other aspects. The small ones could be American instead of European, but they are still being studied. The painting that is signed by Van Herp is dated in 1655, what makes it the oldest object that has been treated in the Paintings Conservation Lab.

The paintings have been photographed, non-destructive analyses were performed (UV photographs and IR reflectography), and samples were taken to identify the painting technique and materials. In addition, metal supports were analyzed through X-ray fluorescence to know its composition: four of them are copper plates and one is an iron-tin alloy.

In addition, a wide research was made to understand the technique used by Flemish artists in the making of paintings on these supports, that are so different to canvas, and to collect information on the most appropriate methods and materials to restore paintings with these characteristics. Some of the damages are distortions of the support, ground and paint film losses, abrasion, lack of adhesion to the support, corrosion, yellowing of the varnish, previous interventions in bad condition and over-paints that cover big areas. In addition, two of them had cradles, which showed lack of adhesion to the copper plate in some areas. It is believed that environmental conditions may have contributed to the damages, because Talca is a dry and hot city in summer, and cold
and humid in winter, so the paintings will be returned with recommendations on proper exhibition and deposit conditions.

In order to perform treatments in the proper way, prototypes were made with copper plates, to make tests of adhesion, consolidation, fillings and chromatic reintegration. At present we are working in cleaning and consolidation, and then the other stages of the restoration will be executed.

Traditionally, many conservators have preferred daylight, and specifically northern daylight, as the preferred source for inpainting. Unfortunately, the availability and control of northern daylight limits the amount of time, and the location in which it can be used as the primary source of illumination. Therefore, supplementary and alternative sources of illumination for inpainting are necessary. What are the essential characteristics of northern daylight that make it a preferred source? What criteria should be used to select viable alternative sources of illumination?

This presentation will analyze the key components that make daylight a preferred source for inpainting, including such characteristics as color temperature, color rendering and light distribution. It will also take into account the fact that many artifacts will ultimately be exhibited at a color temperature that is extremely different from northern daylight and how this should influence the selection of an inpainting light source.

A primary focus of the talk will be the importance of selecting an appropriate color temperature with adequate color rendering properties. In order to illustrate the importance of color temperature and how appearance is altered at different color temperatures, a live demonstration of this phenomenon will be presented.

The goal of the presentation is to suggest that there is an underlying technical basis for color temperature selection that takes into account the fact that objects may be exhibited in a variety of different color temperatures. Most importantly, normal conditions of exhibition generally utilize a warm color temperature source whereas inpainting with northern daylight is done at a very cool color temperature. Research published by the author in conjunction with the National Institute for Standards and Technology will be described which will provide the basis for a theory regarding color temperature preference and its significance in the selection of an appropriate inpainting source.

The Virgin and Child with Saint Anne attributed to Andrea Salai, an associate of Leonardo da Vinci, came from the Hammer Museum at the University of California Los Angeles to the Paintings Conservation Department at the J. Paul Getty Museum for study and treatment in preparation for an exhibition at the Museé du Louvre. Dated to 1500-1524, it is a scale version of the same subject painted by his master now at the Louvre, and was almost certainly created in Leonardo’s studio. The Virgin and Child with Saint Anne has come down to us in remarkable condition from both a structural and aesthetic point of view. The panel has been virtually unaltered since it was constructed and the paint surface remains very much intact with only a few discrete losses. This paper will describe aspects of the painting technique for which analysis of cross-sections greatly enhanced our understanding of it. Some of the interesting findings include a methodical approach to the paint build-up with the occurrence of intermediate varnish layers, and evidence of a textile and the hand used to manipulate blue and red glazes.

Depicting the aftermath of a carnivalesque episode in the infamous and glamorous Maison d’Or, Paris, Thomas Couture’s Supper After the Masked Ball could be described as itself suffering from poor judgements, a tendency to excess, and weakness for immediate gratification. A painting now important to art history and notorious in its day, it nonetheless spent the last 90 years in storage, largely ignored except for episodes of invasive treatments – two linings and at least two campaigns of cleaning and restoration. The painting is once again under treatment, now at the National Gallery of Canada.

This is not an uncommon story for objects in many collections today. As art market prices rise beyond levels most museums and collectors can manage, objects with problematic histories often become an area of focus. We are frequently faced with the legacy of decisions and common practices within conservation made at a time of development, where historic, craft practices were confronted by practitioners at the limits of their understanding, employing new procedures.

In Supper After the Masked Ball, beyond at least two partial and selective cleaning procedures, the treatment sought to undo critical changes wrought by glue-paste and wax-resin linings, leaving a large painting (180 x 228cm) de-lined and not re-lined. The conservation involved a series of structural and restoration treatments to both the painting and its stretcher. Partly, this treatment occurred because the verso of the canvas was used by Couture, as was his habit, to test tint combinations and paint consistencies for other paintings, possibly in a teaching context within his atelier – information typically now lost. This treatment also occurred in part because it is common practice today – attempting to reverse changes made by our forefathers – both in the museum sector and in the realm of private practice, where recovery of ‘authentic’ objects can bring broad benefit and is seen as profitable and desirable. In doing so, we likely bring further issues, both beneficial and potentially problematic, to the fore. This presentation elucidates a methodology for confronting key structural issues clumsily sidestepped by traditional lining practices, using Couture’s Supper After the Masked Ball as a case-study.

In addition to the treatment of the painting, the original Beaux-Arts frame for the painting was also restored, having spent nearly a century off the painting, stored in its shipping crate. The restored painting and its frame will be the subject of a focus exhibition at the National Gallery of Canada and the Vancouver Art Gallery, with web-based content focusing on the essential role of conservation, and additionally on the importance of professional development of emerging conservators through sponsored fellowship initiatives. The painting is expected to make a full recovery from its hangover.

In March 2013, news broke that the Palace Hotel in San Francisco would be selling its historic 1909 Maxfield Parrish wall painting at auction in New York City. Due to the public response the owners responded to the community and made the decision to keep the painting. Already en route to New York when the reversal came, the owner decided to proceed with the previously planned surface cleaning to be done on the east coast. The conservators at Rustin Levenson Art Conservation Associates were contracted for this treatment having cleaned and conserved Parrish’s 1906 New York City wall painting, Old King Cole, in the St. Regis Hotel. The opportunity to examine and analyze The Pied Piper of Hamelin, which has never been lined or had its original varnish removed, was a rare and fruitful endeavor. New information about Parrish’s materials and methods were discovered. The surfactant used for surface cleaning was water-soluble, readily biodegradable, and is considered an alternative by the EPA’s DfE and CleanGredients, 2011. In addition, an alternative to organic solvents was found when testing methods for removal of a non-original alkyd layer.

Dutch artist Piet Mondrian was born in Holland in 1872 and trained at the Rijksacademie. His work of the 1890s was influenced by the contemporary styles of the day: the Hague school, the Amsterdam Impressionists, and Symbolism. Shortly after a 1905 van Gogh exhibition at the Stedelijk Museum, Mondrian’s work transitioned to Neo-Impressionism or “Luminism”, where he explored color and contour. By 1909 he would have his first retrospective at the Stedelijk where he was regarded as a leader of the avant-garde. Studying the style of the day he embraced the transition from Luminism to Cubism and moved to Paris in 1912. He immersed himself in the café and salon scene with fellow artists such as Léger, Rivera, and Braque. He would travel back and forth from Holland to Paris, until the outbreak of World War I would force him to stay in the Netherlands. From 1917 to 1920 he painted experimental works and wrote for van Doesburg’s De Stijl , where in an autobiographical account of his own painting career he expressed, “Only the primary colors—red, blue and yellow—filled in with white and black were required in order to express universal light.” Returning to Paris in 1919, he wrote Le Néo-plasticisme in 1920. He continued to write and to paint throughout the 1920s and 30s and was exhibited throughout Paris, Germany, the Netherlands, and the United States. As the second World War approached he moved to London in 1938 and finally New York in 1940 where he died in 1944 at the very height of his career.

With twenty five of his works, spanning from 1902 to 1944, the Museum of Modern Art holds the most comprehensive collection of paintings by Mondrian in North America. For the last 4 years the conservation department has continued to utilize ever developing technology to study Mondrian’s sixteen oil paintings through examination, documentation, technical analysis, re-treatment, and inter-museum collaboration with colleagues such as conservators and curators at the Gemeentemuseum Den Haag. Technical examination including imaging, X-radiography, Reflectance Transformation Imaging, and X-ray fluorescence spectroscopy with multivariate analysis have been carried out on the majority of the collection. This research is presenting stratigraphic elemental palette information, transitions in his type of paints and medium, a plethora of compositional changes, as well as evolutions in his paint layering technique.

Many of Mondrian’s post 1917 works have exhibited cracking and paint lifting due to intra- and interlayer cleavage of ground and paint. In the past these instabilities warranted lining treatments. The information gleaned through this technical evaluation is expected to produce data that may correlate current and past condition issues with the artist’s material choices and application techniques. Ultimately the collective documentation will be migrated to a Mondrian database to provide the MoMA as well as other institutions and art historians with a more comprehensive understanding of this critically important body of Piet Mondrian’s work.

Throughout his career, Georges Seurat devoted himself to the current color and aesthetic theories of his time. Early on, he began applying these theories to canvas, fine-tuning both his technique and selection of materials, culminating in his mature style, pointillism, around 1886, exemplified by A Sunday Afternoon on the Island of La Grande Jatte. This study investigates an early work by Seurat, Vase of Flowers, c. 1878 - c. 1879, in the Harvard Art Museum’s Wertheim Collection, painted around the time he quit the École des Beaux-Arts in Paris in 1879. A number of recent studies (Kirby, Jo. et al. 2003; Herbert and Harris 2004) have characterized Seurat’s later style, technique, and material choices; there is, however, a dearth of material about his earliest works. The goal of this study is to gain a better understanding of Seurat’s early technique and style, especially when compared to his later works.

Overall, the painted structure of Vase of Flowers is complex and shows just how much forethought and planning Seurat invested in a painting. One facet of his layering system in Vase of Flowers is prominent brushwork throughout most of the composition that has no correlation to the painted objects within the composition. Cross-sections reveal that this texture is not in the ground, but rather in between paint layers: it is part of a layering system that involved abrading the top paint layers to reveal certain colors side by side. Cross-sections, SEM-EDS analysis and mock-ups helped to better understand this process. Furthermore, compositional changes and reworking of the composition visible in the X-ray may indicate Vase of Flowers was only a study, never considered a finished work.

Seurat was a meticulous artist, using materials and methods of paint application as a means of integrating theoretical concepts into his paintings. In Vase of Flowers, he was experimenting with a number of different techniques, though there is reason and theory behind every choice. Vase of Flowers can be viewed as a stepping-stone in Seurat’s career, as he works toward Pointillism.

The attribution of the portrait of Pierre-Edouard Baranowski by Amedeo Modigliani in the Fine Arts Museums of San Francisco (FAMSF) has been questioned on several occasions during its thirty-year history in the collection. Long complicated by the active market for forgeries of the artist’s work that arose soon after his death in 1919, Modigliani scholarship has been marked by a general wariness of previously unpublished works. FAMSF painting’s omission from earlier catalogues of the artist’s oeuvre, gaps in its provenance, and its relationship to another well-known depiction of the sitter cast doubt in the minds of some experts, and the portrait was formally demoted to “attributed to” status in the mid-1990s.

Prompted by the family of the original donor to revisit the attribution of FAMSF’s painting, a new technical study took place in 2011-2012. It was found through the examination and comparison with works by the artist in other collections that many of the idiosyncrasies of the painting that were initially taken as signs that it is not authentic are the very reasons for a favorable attribution. In the course of the study, the enormous influence that bias can play in our approach toward research was recognized. In this paper, the case for the restoration of the portrait’s status will be discussed and the subjective nature of visual perception will be explored.

The picturesque stone Fort Herkimer Church is the oldest church remaining in the “Leatherstocking” district of upstate New York. Although the church likely began its existence as part of the original defenses of Fort Kaouri (Fort Bear), assembled around the homestead of the Herkimer family during the French and Indian War, the current structure began as a single story stone building in 1767.

During the Revolutionary War, Fort Herkimer was rebuilt as a defensive stone and earthwork perimeter to protect the church. Later, in the years between 1812 and 1814, a second story was added to the church and the interior was refitted. At that time a new church pulpit was installed. The church is located on the south side of the Mohawk River/ Erie Canal, and during the construction and later reconstruction of the canal, the surrounding defensive walls were dismantled and repurposed in the canal works.

By the 1960’s the church had reached a state of neglect and deterioration. However, a local funeral director named Donald Fenner recognized the historic value of the site and began a forty year long program of restoration beginning in the 1970’s. By 2006, largely through private funding, the church had been carefully stabilized and decayed architectural elements restored.
As one of the last tasks of this long project, the pulpit was being prepared for a new coat of white paint using disk sanders, when the painting crew began to uncover a complex polychrome decorative scheme. Excited by this discovery the crew continued working, uncovering much of the original paint layer before realizing that the process was not without collateral damage.
This presentation will discuss the challenges of removing the remaining white lead overpaint and identifying and restoring the original, and unique, polychrome surfaces.

Object conservators at the American Museum of Natural History (AMNH) conducted a project focusing on the treatment of a large collection of monumental wooden carvings from the Northwest Coast (NWC) from 2011-2013.  Approximately 80 carvings, many of which are painted, were collected between the 1880s and 1920s and have been in open display in the museum for over a century.

Many of the carvings had significant condition issues resulting from of a combination of factors, including deterioration due to original installation in the wet environment of the NWC, and long term open display at AMNH without climate control or protective barriers.  Heavy dust accumulation resulting from high visitorship necessitates regular surface cleaning of fragile wood and painted surfaces.  Previous undocumented interventions by museum staff prior to the establishment of a conservation laboratory had also contributed significantly to both structural and surface problems.

Because of its scope, this project posed a number of practical and logistical constraints requiring both creativity and adaptability to successfully address. Planning and execution were often complicated by staff and budget limitations and the large size and number of objects involved.  Challenges encountered and solutions generated will be addressed, including addressing ethical issues appropriately with limited resources, development of efficient documentation and low-tech rigging and moving techniques, and investigation of complex structural and surface issues within the limitations of the project. Treatment procedures that adapted and streamlined standard wood treatment protocols for consolidation and fills were developed, as were controllable cleaning systems for the fragile and complex painted surfaces.

This paper wants to share with colleagues how the guiding principle of reversibility has been translated into the practice of frame and gilding conservation during the past quarter century at the Rijksmuseum in Amsterdam. With a plethora of synthetic materials available it is often hard to see the forest for the trees. It sometimes leads to overly complicated approaches, or to clinging to just that one favorite material even though the case at hand may not call for just that.

In a field where art history and material sciences overlap, different opinions about treatment approaches and end results are inherent. This is not a problem but a pleasure to participate in. The presented case studies will touch upon the technical aspects of restorations as well as frequent communications with other conservators and with curators. Collaboration with colleagues has traditionally taken place within a rather large forum of conservators and curators, especially within the paintings department at the Rijksmuseum.

The presentation intends to shed light also on reasoning and common sense that have lead to the choice of contemporary media for gilding restoration like for example aquazol, plextol and acrylics in combination with traditional materials such as rabbit skin glue, shellac, dextrin or gum Arabic. Economy of means is important, not just in terms of the cost of labor and materials, but also as a process with its own beauty and appeal. Usually there is more than one approach possible to approach a conservation project. Individual preferences and talents of the conservator are also valid factors in deciding on a treatment approach. For example, in restoring or part of a sculpture, or ornamentation, one colleague prefers to restore by carving a missing piece out of wood while another is more expedient at modeling it out of paper mache. The end result of both approaches can be equally effective and convincing if done with skill and finesse.

Case studies include the conservation and restoration of picture frames and a gold ground panel painting by Lorenzo Monaco (Stigmata of the Holy St. Francis of Assisi; ca.1420). Some frames are still original to their paintings. The discussed frames are connected to works by the following painters Cornelis Kruseman (Piety; frame & painting 1823), Georgius Johannes Jacobus van Os (two large pendant still lives; frames & paintings 1817 and 1818), Pierre Prud’hon (Portrait of Jan Schimmelpenninck and His Family; frame & painting 1801-1802), Ludolf Bakhuysen (frames 1661), Cornelis Engebrechtsz (Christ in the House of Mary and Martha; frame & painting 1515-1520), Master of  the  Conversazione di Santo Spirito (Madonna and Child; frame last quarter 15th C.).

With special thanks to Camille Marchand from The Netherlands, David Beaudin from North Carolina, Lea Wegwitz from France and Satu Rantala from Finland, who contributed to the work in several of the case studies to be presented.

Almost a quarter of the Walters Art Museum’s approximately 2500 paintings are on wooden panel supports. These range from the early 12th up to the 19th Century and come from Northern and Southern Europe, Ethiopia and Thailand. A number of the panels are in a fairly pristine state but most have received a variety of structural treatments by many different hands over the years. Some had undergone major work in Europe prior to entering the collection, while others received treatments at the Walters both before and after the introduction of climate control to the buildings; including the infamous “wax tank” treatments. Damage to the substrate caused by these treatments, sometimes in combination with inherent vice and climate issues, often had a harmful effect on the paint layer resulting in paint loss. Several of these treatments have resulted in increasingly challenging problems for the conservator as we look for practical solutions to structural problems with panel paintings.
Surveying the Walters panel collection allows for an historical overview of structural treatments to panel paintings, both in Europe and North America, and illustrates the evolution of more conservative methods of treatment concomitant with the development of better climate control and a new philosophy that recognizes the importance of the wooden support to the artwork as a whole.

In the debate about safe climate ranges, the majority of scientific literature concerning the reactivity of wooden objects which supports the new proposed guidelines has been carried out in laboratory conditions, assuming that the characteristics of the sample can be safely extrapolated to real size objects. Some field measurement campaigns have been carried out in an attempt to detect the most irreversible damage element, the crack, although there is probably more to investigate regarding the long term warping of real objects under fluctuations. This paper will focus on the latter aspect.
Case studies monitoring long-term warping of panel paintings have been conducted for many years. The mechanical monitoring has been combined with microclimatic logging, in order to provide quantitative information directly related to the environmental conditions; these data are useful to validate mathematical models that eventually may predict the long-term behaviour of objects.
The climate fluctuations can have both temporary and permanent effects on hygroscopic objects and they are a potential cause of damage.
Although there is long-term evidence of the generally positive effects of a microclimate within the standard range of allowable fluctuations, we lack wide experimental data regarding the effects of broader ranges on real objects over a long period of time.
Panel paintings are useful in representing the complexity of possible reactions.
Due to the specificity of each artwork, both from its structural point of view and from its previous microclimatic history (for the most part totally unknown), the analysis of an artifact’s response to short- and long-term variations can supply useful information about its “individual” sensitivity to the exhibition microclimate, suggesting the adoption of more or less rigid parameters.
The benefits of such an approach are many, both from the preventive conservation point of view and as a support for conservation interventions. The methodology can be useful in monitoring objects in transit and to evaluate the effects of structural interventions.
Due to the size of the instruments employed, the methodology is minimally invasive. Since it is placed on the back of the support, the device can also be used while the object remains on exhibition without disturbing visitors and, thanks to recent improvements, it can be easily detached and exactly repositioned without affecting the quality of measurement.
From the scientific point of view, widening the data-base of monitoring experiences would benefit  the understanding of this sensitive issue in the conservation of panel paintings.

Warped panel paintings were commonly treated in the 19th and early 20th Centuries by thinning the panel to increase flexibility and to obtain a flat surface on which to attach a cradle. As is well known, the sliding cross-members frequently became blocked and accumulated stresses eventually caused cracking, splitting, and other deformations of the panel. Subsequent treatments often require removal of the cradle in order to repair the splits and adjust the surface curvature. After treatment, the panels are often too fragile on their own without additional secondary support to increase stability.  The need for increased stability while still allowing for expansion, contraction, and cross-grain flexing of the panel during humidity fluctuations eventually led to the use of springs.
Springs were first used in the design of secondary supports for panel paintings in Italy in the mid 1970’s. Research began at the Istituto Centrale del Restauro in Rome and later continued at the Opificio delle Pietre Dure in Florence.
In recent years, new designs for controlling movement in wood panels have been developed at The Metropolitan Museum of Art. This paper will review the most recent designs of the spring mechanisms themselves as well as refinements to certain characteristics of the support strainers. 

The collection of the Wallraf-Richartz-Museum in Cologne, Germany includes a late medieval panel painting depicting Scenes from the Life of Jesus Christ: The Two Banquets. Originating from Cologne and dated around 1450, the panel once formed the cover of a wooden chest, and its two sides are today extraordinarily different in appearance, function, and condition. The recto, which would have been on the inside of the chest and only visible upon opening the lid, resembles an altarpiece depicting highly detailed figurative scenes from the life of Christ; the verso, or outside of the chest, is painted more modestly and consists simply of a monochromatic red paint layer with decorative gilding.

Owing to its exterior position and functional nature, the decorative verso has sustained a greater amount of wear and shows significant signs of use. Moreover, when the lid was separated from the body of the chest, the hinges were removed from the verso, the panel was framed as a painting, and the recto with the figurative scenes was treated as the primary work of art: this side has been carefully preserved and retouched. Meanwhile, the verso was subjected to sub-par treatments, poor-quality conservation materials, and neglect. 

For the double-sided display of the panel in the context of its original function in the exhibition „The Painters’ Secrets: Cologne in the Middle Ages” taking place from September 20 2013 - February 9, 2014, the verso required treatment during the summer of 2013. The extreme discrepancy in condition between the two sides necessitated the methodical development of a restoration concept prior to treatment.

The major questions throughout the treatment centered on the level of intervention appropriate in order to reflect the functional nature of the object, while bringing the verso to a condition more akin to that of the recto and to a state of preservation more consistent with the other works within the exhibition. Treatment decisions were required that reflect the work’s original function as well as its recent history as a painting, while acknowledging the physical changes it has experienced over time. Specific challenges included developing a philosophy of retouching exposed ground, exposed raw canvas, large areas of loss, and loss to the gilded pattern.

This paper will treat the historic use and context of the object and provide information regarding its materials and construction. More importantly, it will develop an overview of the ethical and practical considerations of the restoration of this object, as well as present a summary of several similar case studies. The treatment philosophy is proposed as a potential model for complex objects with similar challenges.

The Ghent Altarpiece by Jan and Hubert van Eyck (1432) is one of the most iconic works of Western Art as it embodies the birth of new skills and vision. It is still housed in Saint Bavo Cathedral (Ghent), the site for which it was created. Here it is seen by thousands of visitors a year. In October 2012, a five-year 1.2 million Euro restoration project by a team of conservators from the Royal Institute for Cultural Heritage (KIK-IRPA) began for this work.

A painting with this level of cultural importance could not be taken off view for an extended period of time. The decision was therefore made to conduct the three-phase treatment in a gallery in the Museum of Fine Arts Ghent behind a large glass window so the public could follow every step. This approach created the need to inform the visitors who are not accustomed to witnessing conservators at work. The window maintains a barrier but with its transparency, it creates new opportunities for engagement. How can the demystification of conservation work influence the perceived value of painting conservation and collection care? In what new ways can information exchange happen in this specific situation? Are there chances for misunderstanding or negative misinterpretation on the part of the museum visitor?

This paper will address the early experiences of conservators who, by working in the public eye, take on unforeseen responsibilities and challenges. These conservators must find the equilibrium between assisting with public outreach and conducting the treatment; all this while maintaining constant dialogue with the different partners and safeguarding a strict deadline for the project.

 The author will explore these experiences in this very specific and complex project in the hope they can be useful and instructive for similar undertakings in the future.

The deterioration of an early 15th century panel painting (originally from an altarpiece since dismembered) attributed to the Spanish artist Luis Borrassa, has been studied to devise a method to remove intractable restoration materials from the painting, particularly on the blue robes of the Christ figure, which appeared black.

Many panel paintings from the 14th to 16th centuries have come down to the present day with the original colors altered by previous restoration. This is especially true in the blue robes of Christ or the saints in which lapis lazuli or azurite blues are the primary pigment. Historically, the blue pigments are loosely bound and easily abraded when subjected to traditional solvent cleaning methods typically used for the removal of soot, wax, and natural resin varnishes. Often compounding the problem is the consolidation of the paint layer with animal glues and later with drying oils, which have often cross-linked and darkened, in some cases to almost black. This is further complicated by the addition of restoration paint and glazes to cover losses and abrasion.

This is the case with the Borrassa, where the blue robe of Christ looked essentially black. A half century ago in an unsuccessful attempt to correct the problem and conceal additional damages to the painting, a restorer applied a pigmented varnish of a dark amber color. The toned varnish imparted an overall uniform tone to the painting and cosmetically obscured the existing damages. In the current treatment, solvent methods were effective in removing the toned varnish from the painting, but not the composite layer of old consolidant, cross-linked drying oil, and restoration from the blue robes and other blue passages in the composition.

After extensive analytic studies the intractable restoration layer was identified by conservation scientists from the University of Pisa in conjunction with Duke University using GC/MS, FTIR, Scanning Electron Microscope and Microanalysis. The materials in the composite layer were identified as a combination of cross-linked drying oil and animal glues combined with natural resin varnish tinted with pigment. Testing was carried out successfully with the Er:YAG laser and the encrustation was removed or substantially reduced leaving intact the original lapis pigments.

This presentation will consider the analytic findings and demonstrate the Er:YAG laser methods for removing intractable materials without causing damage to the original surface. The Er:YAG laser operates at 2.94 microwatts, using pulsed laser energy to vaporize debris. The laser energy is confined to a surface depth of no more than a few microns, providing a natural barrier to energy penetration into underlying layers.