Month: July 2014

42nd Annual Meeting – Book and Paper Session, May 29, 2014, "Digital Rubbings. Monitoring Bookbindings with the Portable Mini-Dome (RICH)” by Lieve Watteeuw

In this talk, Lieve Watteeuw showed images produced by the Reflectance Imaging for Cultural Heritage (RICH) project and demonstrated the functionality of the Mini-Dome module. I was excited to see this presentation after reading advertisements for the “New Bownde” Conference at the Folger Shakespeare Library last year, in which the RICH project and Mini-Dome were featured. Fortunately, for those unable to attend the presentation, extensive documentation about the project is available online through the project’s webpage and blog.

Downloaded from: http://portablelightdome.files.wordpress.com/2013/11/foto-1.jpg
The Mini-Dome module

The Mini-Dome module is a small, hemispherical-shaped imaging device that is tethered to a laptop. The module creates dynamic digital images through polynomial texture mapping, a technique commonly referred to as Reflectance Transformation Imaging (RTI). This technique involves taking a series of images from a fixed camera position, while changing the angle of lighting, in order to reveal the surface of an object. The original dome was created in 2005 at Katholieke Universiteit Leuven for reading cuneiform tablets, but has since been used to image bindings, illumination, wax seals, cuir bouilli, and other cultural objects. The current module is equipped with a single 28 MP digital camera and 260 white LED lights to capture a total of 260 images in approximately four minutes. Watteeuw showed a video of the Mini-dome in action during her presentation, but readers can view a similar video here.
KU Leuven, Maurits Sabbe Library, second quarter 16th century, SPES Binding, panel stamp on brown calf leather.
Example of images and filters. KU Leuven, Maurits Sabbe Library, 16th century SPES Binding, panel stamp on brown calf leather.

After capture, Watteeuw described how the images are processed by software and interpreted by seven dynamic filters. She  demonstrated some of these filters, including sharpen, shading, generate models, line drawings, and sketch.  Using the mouse or interface buttons, the user can zoom in, drag the image, or change the direction of lighting in real-time. For those that would like to experience the software interface, a web viewer is available here. Watteeuw reports that the software suite can also export to 3D shaded or rendered modes.

Watteeuw’s presentation included a demonstration of a measurement tool built into the image processing software. The tool can be used to measure the distance between two points or generate a height map for a portion of the object. This blog post includes an image of a height map created on the blind-tooled surface of a leather binding. Watteeuw explained that by scaling the image, the measurements can be accurate to 10 microns.

Watteeuw’s presentation included several examples of how the Mini-Dome could be used to learn more about the production of a binding. Images of a late 15th century book of hours were manipulated with filters to show tool marks on the uncovered wooden boards, providing evidence of how the boards were shaped and the lacing of the sewing supports. A second example showed a 16th century book (pictured above and described here), in which the binder scored a vertical line in the leather to align a large, central impression. Watteeuw described instances in which previously unknown marks or designs were revealed by manipulating the filters or direction of the lighting, such as three leaves emerging from an emblem design, or shallow impressions from a decorative roll being more clearly defined. This tool could be quite useful for identifying individual finishing tools and documenting how they changed or became damaged over years of use.

In addition to leather bindings, Watteeuw shared images of Belgian damask silk, remains of a ribbon, and embroidered bindings from the Folger Shakespeare Library. Once again, the dynamic filters in the software suite were applied in order to enhance details of the objects. The “sketch” tool provides clear images of weaving and embroidery patterns and could be very useful to textile historians and conservators. The measurement tool could also be used to gather data on the thickness of threads or cord used to construct the object.

ccsmicrodome
The Micro-Dome module fitted to a copy stand.

The RICH project will continue until 2015 and additional investigations are already underway. Watteeuw reports that the topographic data from an object is exportable into spreadsheet form. Engineers on the team are currently exporting high points of objects scanned to create a large data set for further analysis. Additional projects include the development of optical character recognition (OCR) for specific tool shapes or patterns on bindings. Testing is proceeding on a smaller “micro-dome” (pictured above) that  is constructed in two pieces so that it can be placed inside the opening of a book to capture images of the gutter or surface of a page. Watteeuw described a student research project currently in progress to measure sewing in manuscript textblocks.

Two questions were asked by audience members following the presentation. The first individual asked if a database of the existing images is available. Watteeuw answered that an open access database of all images captured would be ideal; however, since this is a research project using prototypes, the team is collaborating with institutions to link with existing databases. A second audience member asked if any attempts had been made to identify tools of various workshops. Watteeuw replied that a corpus was needed before any comparisons could be made.

Advanced imaging technologies, such as RTI, offer tremendous opportunities for the study of cultural objects and for digital libraries in general. The RICH project has produced a suite of tools that could be used by scholars and practicing conservators to gain a better understanding of an object’s composition and production. Wider use of devices such as the Mini-Dome in imaging collections of note and greater access to the software suite is required in order to exploit the full potential of the technology.

42nd Annual Meeting – Book and Paper, 42nd Annual Meeting, Book and Paper Session, May 29, "Treasure from the Bog: The Faddan More Psalter" by John Gillis

Faddan More Psalter
Faddan More Psalter

John shared with us his particular torment, a project that has occupied him daily for over six years, a highly deteriorated psalter uncovered from a peat bog in 2006. He still has his sense of humor, even though he freely admitted the project was pretty nightmarish at times. The psalter was uncovered from a commercial peat bog in July of 2006. Research suggests that the sphagnum moss in these bogs is what helps organic material survive so much better there than in regular soil, as the moss has a tanning effect on the organic material.
Once the psalter was uncovered, work stopped in order to rescue the fragile book. The psalter was covered in a wet layer of peat, then silicone Mylar and finally cellocast resin bandages were wrapped over the psalter to keep it wet until help arrived. This was exactly the right thing for the bog excavators to do. These men were not archaeologists or conservators themselves, but they knew what to do to keep it stable until conservators could arrive due to extensive museum outreach in the area. Local museums have provided a lot of training in order to help protect the wealth of archaeological materials located in Ireland’s bogs – most of which are commercially owned. Back at the lab in Dublin, the manuscript was kept wet and cold – at 40°C in a walk-in fridge. The media hyperbolically reported the discovery of the Psalter as being an apocalyptic omen due to a misidentification of one of the psalms. Really, psalters like this were used by monastic novices to learn their bible.
John’s first goal was to establish a collation map of the psalter. This usually easy task took two years due to the extensive trauma to the book. The psalter has five quires, 60 folios, no flyleaves, and it does not follow the insular nor the continental tradition of orienting the hair and flesh sides of the parchment folios. As John said, it seems to be “in the best Irish tradition, of completely ad hoc”.
Using a grid system, John mapped out each chunk of parchment before putting it through the drying process. He used a database to compile the veritable mountains of information the treatment of the Psalter generated. They cleaned the manuscript with water, removing thousands and thousands of seed pods with tweezers. One of the most challenging parts of the project was the “letter fishing” the group had to go through, to snag words and letters and letter-bits out of the bog. The tanning agents in the iron gall ink tanned the vellum so that frequently words or letters… or letter-parts would survive when the rest of the inner manuscript did not. In general, the inner portion of the manuscript was more likely to dissolve than the outer edges, which were exposed the tanning elements of the bog, would be preserved.
After cleaning, the Psalter page fragments underwent hyper spectral scanning, which John and his team undertook in an effort to read some of the illegible areas of the manuscript. After scanning, the fragments were ready to be dried.
The process that creates vellum creates a lot of tension in the material, and that tension shows itself most dramatically when drying wet vellum…. in intense shrinking and warp. John’s talk mostly focused on the de-watering of the vellum. Using some old historical vellum flyleaves the he had laying around the lab, John recreated putrefied vellum on which to test various drying methods. He and his crew kept track of changes in color, size and flexibility. After months of testing, they decided to proceed with a solvent bath of alcohol. They needed to restrain the vellum while it dried to minimize dimensional changes. The solvent exchange took place in a vacuum sealed bag that exerted even pressure against the entire fragment. This neatly solved the problem of restraining fragile vellum.
The National Museum of Ireland has a page devoted to the Faddan More Psalter project, with the full report on the psalter freely available.

42nd Annual Meeting – Paintings, May 30, "Piet Mondrian: Technical Studies and Treatment" by Ana Martins, Associate Research Scientist, MoMA, and Cynthia Albertson, Assistant Conservator, MoMA

NYC’s Museum of Modern Art owns sixteen Piet Mondrian oil paintings, the most comprehensive collection in North America. From this starting point, conservator Cynthia Albertson and research scientist Ana Martins embarked on an impressive project, both in breadth and in consequence—an in-depth technical examination across all sixteen Mondrians. All examined paintings are fully documented, and the primary preservation goal is returning the artwork to the artist’s intended state. Paint instability in the artist’s later paintings will also be treated with insight from the technical examination.
The initial scope of the project focused on nondestructive analysis of MoMA’s sixteen oil paintings. As more questions arose, other collections and museum conservators were called upon to provide information on their Mondrians. Over 200 other paintings were consulted over the course of the project. Of special importance to the conservators were untreated Mondrians, as they could help answer questions about the artist’s original varnish choices and artist-modified frames. Mondrian’s technique of reworking areas of his own paintings was also under scrutiny, as it called into question whether newer paint on a canvas was his, or a restorer’s overpaint. Fortunately, the MoMA research team had a variety of technology at their disposal: X-Radiography, Reflectance Transformation Imaging, and X-ray Fluorescence (XRF) spectroscopy and XRF mapping were all tools referenced in the presentation.
The lecture discussed three paintings to provide an example of how preservation issues were addressed and how the research process revealed information on unstable paint layers in later Mondrian paintings. The paintings were Tableau no. 2 / Composition no. V (1914), Composition with Color Planes 5 (1917), and Composition C (1920), but for demonstration’s sake only the analysis of the earliest painting will be used as an example here.
Tableau no. 2 / Composition no. V (1914) was on a stretcher that was too thick, wax-lined, covered in a thick, glossy varnish, and had corrosion products along the tacking edges. Research identified the corrosion as accretions from a gold frame that the artist added for an exhibition. The painting has some obviously reworked areas, distinguished by dramatic variations in texture, and a painted-over signature; these changes are visible in the technical analysis. The same research that identified the source of the corrosion also explained that Mondrian reworked and resigned the painting for the exhibition. XRF mapping of the pigments, fillers, and additives provided an early baseline of materials to compare later works to, as the paint here did not exhibit the cracking of later examples. Ultimately, the restorer’s varnish was removed to return the paint surface to its intended matte appearance, and the wax lining was mechanically separated from the canvas with a specially produced Teflon spatula. Composition no. V (1914) was then strip-lined, and re-stretched to a more appropriate-width stretcher.
It is possible to create a timeline of Mondrian’s working methods with information gleaned from the technical examination of all three paintings. His technique had evolved from an overall matte surface, to variations in varnish glossiness between painted areas. XRF analysis demonstrated a shift in his palette, with the addition of vermillion, cobalt, and cadmium red in his later works. XRF also revealed that the artist used registration lines of zinc and lead whites mixed together and used on their own. Knowing the chemical composition of Mondrian’s paint is vital to understanding the nature of the cracking media and identifying techniques to preserve it.
The underpinning of all this research is documentation. This means both accounting for un-documented or poorly documented past restorations, as well as elaborating upon existing references. Many of the MoMA paintings had minimal photographic documentation, which hinders the ability of conservators to identify changes to the work over time. The wealth of information gathered by the conservation and research team remains within the museum’s internal database, but there are plans to expand access to the project’s data. Having already worked in collaboration with many Dutch museums for access to their Mondrian collections, it’s clear to the MoMA team how a compiled database of all their research and documentation would be groundbreaking for the conservation and art history fields.

42nd Annual Meeting – Paintings , May 30, “The Pied Piper of Hamlin: Color and Light in Maxfield Parrish in the Palace Hotel, San Francisco” by Harriet Irgang Alden, Director/Senior Paintings Conservator, ArtCareNYC/A Rustin Levenson Company

In the spring of 2013, San Franciscans were outraged to discover that a cherished Maxfield Parrish wall painting had been removed from its home in the Palace Hotel and sent to New York to be sold. Prior to auction, it was to be cleaned of the hundred-plus years of accumulated grime and accretions it had been subjected to while hanging in The Pied Piper Bar. Thus, even after the Palace Hotel had acquiesced to public sentiment and agreed to return it to San Francisco, the painting remained in New York to be treated.
Harriet Irgang Alden, of Rustin Levenson Art Conservation Associates, had experience with other Parrish wall paintings, and knew the treatment concerns that were inherent to his working methods. The artist alternated thin transparent glazes of brilliant, unmixed pigments with saturating layers of varnish. This made the removal of a restorer’s varnish on a Parrish painting a fraught process that is typically not undertaken, because of the likelihood of disrupting the original layers. The planned treatment outcome only focused on grime removal. The immediate uniqueness of this Parrish wall painting was in the details of its construction. Despite its substantial size at 5 feet by 16 feet, the Pied Piper was not painted in sections, as Parrish’s other wall paintings were. The painting appeared to have been shipped rolled from the artist’s studio to San Francisco, where a stretcher was constructed for it—possibly of redwood due to the incredible length of the members. Additionally, the back of the original canvas remained visible, and displayed a ticking pattern similar to the canvas used for an 1895 Old King Cole painting. The unlined canvas, as well as the unique stretcher, provides new material evidence of Parrish’s working methods.
Unlike previous Parrish treatments, grime removal on the Pied Piper had revealed a broken varnish layer. Apart from thick brush drips and a pockmarked appearance, there were passages of flaking, which curiously did not reveal dull, unvarnished paint beneath. Instead, beneath the discolored upper varnish there appeared to be a clear, glossy layer of a different varnish, and beneath that were the brilliant blues typical to Parrish’s paintings. FTIR analysis at the Museum of Modern Art in New York verified that there were two distinct varnishes: the crumbling upper layer was an alkyd, and the lower a decolorized shellac. Alkyds like this alcohol-acid polymer were not produced prior to the 1920’s, so they could not have been original to Parrish’s 1909 Pied Piper. The decolorized shellac was stable and was still firmly adhered to the paint beneath. Both original layers had actually been protected from UV and bar patron damage by the alkyd addition.
After an aqueous cleaning removed the grime layer, the conservators were faced with an exciting prospect: could they remove the restorer’s varnish, and in doing so, reveal a pristine Maxfield Parrish painting? Solvents would penetrate through both layers and affect the pigment. A more complex process was tested: methyl cellulose in water was applied, and removed after five to ten minutes, to soften the alkyd layer. Though in initial attempts a scalpel was used, the conservators found that the softened alkyd varnish would lift easily and safely by being pulled up with tape using the ‘Texas Strappo’ method. This technique was successful, and revealed a brilliant and unharmed original varnish layer, but it was also incredibly time consuming.
The Palace Hotel declined to extend the treatment of the Pied Piper to include a months-long varnish removal. The alkyd removal test area was toned to blend back in, the painting was varnished with Regalrez, and the Pied Piper returned home. The non-original alkyd varnish remains, still degrading, but it continues to protect the pristine painting and original varnish beneath. In the future, it will be possible to remove the new Regalrez varnish with naphtha, which does not affect the original shellac varnish. It will also be possible to remove the alkyd layer with the solvent and mechanical methods outlined in the test, and revarnish with Regalrez, and possibly a UV stabilizer. Maxfield Parrish’s vibrant original may not be fully unveiled, but until then, the beloved painting is safely on display.