Category: Topics

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Silver Nanoparticle Films as Sensors to Measure the Emission of Sulfur Gases from Wool Fabrics Degrading Under Ambient Conditions” by Rui Chen

Dr. Rui Chen has been developing optical sensors using silver nanoparticles for the detection and quantization of sulfurous gases. These sensors are meant to serve as an improvement over the metal coupons used in the Oddy test, as silver nanoparticles react faster and with higher sensitivity than bulk silver. Additionally, their reaction with hydrogen sulfide causes the nanoparticles to lose their color, so the kinetics of the reaction can be monitored spectrophotometrically with the decrease in the absorbance spectrum.

To make the sensors, spherical yellow nanoparticles are assembled as a monolayer on a glass surface with a polyethylenimine linker. When the monolayer films are exposed to hydrogen sulfide gas, the observed decrease in absorbance is faster when the concentration of hydrogen sulfide is higher. At concentrations of 10 ppm hydrogen sulfide, for example, the reaction is complete within about an hour, while completion occurs within 4 to 6 minutes at concentrations of 100 ppm.

Furthermore, Dr. Chen has found a linear relationship between the first-order rate constant for the reaction and the concentration of the gas. Thus, an unknown concentration of hydrogen sulfide gas can be calculated based on the reaction rate observed between the gas and the nanoparticle-based sensor.

The sensors have been applied to wool samples aged under UVB light. These samples exhibited the highest emissions within the first 400 hours of aging, with concentrations of hydrogen sulfide reaching nearly 600 ppb per gram of wool. The sensors have also been applied to photograph cases and a box containing naturally aged silk fibers; four of the five objects tested exhibited some emission of hydrogen sulfide to give concentrations that ranged from 33 ppb to about 150 ppb. Future work on this project will involve the development of a user-friendly protocol for the application of the sensors.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Measuring Changes in the Appearance of Surface Textures” by Paul Whitmore

The ability of conservators to accurately describe surfaces is integral to effective documentation and communication in the conservation field. While changes in color can be accurately described by the Munsell and CIELAB systems, changes in the appearance of a surface texture are often described by vague and indefinite terms. The work described by Dr. Whitmore arose from the desire for a new vocabulary for describing the surface texture and appearance of regularly-patterned surfaces such as canvas. His talk presented a background of how we perceive surface texture and some mathematical analyses that can be performed to yield qualitative metrics for describing certain textures.

Texture is not only an artifact of the topography of a surface, but also a result of the illumination of this topography; the appearance of a surface depends on the position and directionality of the light source as well as the distance of the light from the surface. As viewers, we perceive texture from the resulting distribution and contrast of light and dark areas.

The limitations of our perception can be mapped by a contrast sensitivity function, which relates our ability to perceive patterns of varying degrees of contrast with the size of the pattern and the distance at which it is viewed. Changes to texture are often accompanied by changes in contrast; a weathered surface, for example, exhibits decreased contrast between its light and dark areas. In periodic patterns, the contrast can be quantitatively measured by a gray-level correlation matrix analysis. Once this contrast value has been determined, the contrast sensitivity function can be used to calculate the maximum viewing distance at which a pattern of the given contrast can be perceived. This “maximum visibility distance” may serve as a useful metric with which to describe periodic surface textures.

The analysis has been successfully applied to canvases that had been subjected to extreme treatment, and further work will examine the degree of textural changes caused by common conservation treatments. Future work may also investigate other mathematical and image processing analyses for application to different surface textures.

AIC’s 39th Annual Meeting – Paintings Morning Session on June 3, “Industrial Literature as a Resource in Modern Materials Conservation” by Dawn V. Rogala

Artists working in the post-WWI era frequently used industrial products in their work.  This can put conservators in the position of dealing with materials with unknown compositions and behaviors that are not conducive to long-term preservation.  Unfortunately, existing conservation literature does not always provide adequate materials information or case studies for conservators wrestling with these issues.  Expanding literature searches to include period industrial articles can fill in those informational gaps.

Dawn Rogala discovered the benefits of such industrial literature while researching mid-century American oil-based zinc oxide house paint during her postgraduate fellowship at the Smithsonian Institution in Washington, DC.  Her research focused on a group of abstract expressionist paintings and the relationship between their zinc oxide grounds and failure of the paint layers.  She found that industrial literature provided significant evidence of a connection between the choice of materials and the current unstable condition of the paintings.

The period between 1925 to 1950 provided Rogala with the most useful articles, likely due to market demand and frequent product adaptation during that time.  The largest percentage of articles she found were presented by representatives of the paint manufacturers who were focused on promoting the benefits of their paint to consumers.  Those may seem like biased and unreliable sources for accurate information, however such articles often mentioned engineered mechanical behaviors that were considered beneficial in their paint films.  Approximately 25% of the articles in her research were affiliated with scholarly research.  Those articles provided more comprehensive and practical analyses of paint film behaviors with useful reference bibliographies.

Weathering test articles were another rich source of information on paint formulations and behaviors.  The variations in regional weather often caused adaptations in regional paint formulations.  This meant that artists working with a zinc oxide house paint in a mild climate may have worked with an entirely different formulation of zinc oxide house paint than an artist working in a more severe climate during the same period.  It also suggested titanium dioxide’s introduction into house paints in the mid-1950s could have been delayed on a global scale when considering issues of climate influences on formulation changes.

One of the specific examples Rogala gave to illustrate the usefulness of industrial literature referred to self-renewing paint films.  Weathering test articles cited a preference for acicular particles because their brittle nature allowed for microfissures in the paint, which would cause it to slough off in the rain and result in a crisp clean surface.  Another example was the mention that three years was the required life expectancy for engineered paint films according to industrial standards.  While such qualities were acceptable and even desirable in house paints, such paint films pose clear disadvantages for conservation.  In fact, Rogala pointed out a 1909 article that warned about the dangers of zinc oxide paint as a ground layer!

I thought this was an outstanding presentation.  Conservators must be resourceful and adaptable when dealing with unknown, unpredictable materials.  This is a particular necessity when it comes to the conservation and preservation of modern and contemporary artwork.  I appreciate Rogala’s study for delving into the industrial side of zinc oxide and providing an open look at a somewhat unconventional resource for conservation research.

39th Annual Meeting – Joint Paintings/Research and Technical Studies Session, June 3, “Speed, Precision, And A Lighter Load: Metigo MAP 3.0, A Great Advancement In Condition Mapping For Large-Scale Projects” by Emily MacDonald-Korth

Emily MacDonald presented on the usefulness of a new condition mapping program called Metigo MAP 3.0.  She began her presentation with a description of a collaborative project between  the University of Delaware and the Tsinghua University (Beijing) led by Dr. Susan Buck (Winterthur/University of Delaware Program in Art Conservation) and Dr. Liu Chang (Tsinghua University) to examine and document Buddhist murals and polychromy in the Fengguo Temple (Fengguosi), located in Yixian County, Liaoning Province, China.  The four interior walls of the temple are lined with the murals.  The murals were in very poor condition and their contained images were skewed by loss and other damage.

The Metigo Map software allowed the conservation team to map the murals’ condition issues in a short period of time.  The software incorporates mapping, digital imaging, and area measurement tools. The program streamlines the mapping process and is easy to use.  Emily compared the software to known and used techniques of documentation and illustrated the limitations of each.

Metigo Map was created by German company fokus GmbH Leipzig, dedicated to architectural surveying in addition to documentation of large scale conservation projects.

Maps are produced by uploading images into the software.  The images can then be drawn on and annotated.  The program makes the image true to scale and is able to rectify skewed images to proper orientation.  This allows images to be used that were taken from an angle if your subject is not accessible from the front.  By inputting the dimensions of the painting, the software can give exact locations of areas of interest and calculate the surface area of damage.  This feature can also be useful in making time estimates for proposals on big projects.  Image processing setting allows for photo editing to aid mapping.   Mapped images can then be exported as tif. files and opened in other programs.

For the presentation, Emily chose three murals to be representative of the condition issues they noted overall.  The conservators worked as a team, using Metigo Map to document the condition of the murals.  After the murals are mapped, the maps can be compared easily for condition issues.  The software can also be used to map the locations of samples.  Annotations can be made to the maps for future referral.

For large scale projects or projects particularly difficult to photograph, users can use the tiling function of the software to piece together the rectified image.  This allows for seeing the project unobstructed.

Emily also illustrated how Metigo map can be used to document experiments.  She has also used the software while working on a graffitti removal research project at the Getty to document surface changes and areas of treated surfaces.

Emily summed up the talk with an excellent slide comparing the pros and cons of the software.  The pros included:  easy mapping, image processing, rectification, measurement functions, compatibility with other software, and easy interface.  Cons included:  requires initial training, no white balance (but this can be done on photoshop beforehand), and cost (more expensive than adobe creative but less expensive than autocad).

39th Annual Meeting – Joint Paintings/Research and Technical Studies Session, June 3, “Raman Revealed: A Shared Internet Resource for the Cultural Heritage Community” by Suzanne Quillen Lomax

Suzanne Lomax presented on IRUG’s (Infrared and Raman Users Group) latest efforts to distribute data for Raman spectra.  She began the talk with a brief discussion on the history and mission of IRUG and their new initiative to create a Raman spectra database due in large part to a $239,650 two-year IMLS grant awarded to the Philadelphia Museum of Art in partnership with IRUG.    The 118 institutional members will contribute to the database which will be used by individuals, scientists, conservators, and students to study cultural heritage.  The Raman database will be maintained on their website.  IRUG has biennial conferences and their website www.irug.org contains information on grant funding and the conferences.  All of the coauthors for this paper are board members of IRUG.

Suzanne described the model for the database and compared it to the widely used infrared database.  By 2009, the IR database was 100% digitalized, available on CD, and in two print volumes.  The latest edition contains over 2,000 infrared spectra. On the current IRUG website, members are able to search terms and match by keyword resulting in a hit list for searched components.  The resulting spectra provide in their file name link the mode of collection and where it was collected.  The largest represented group in the IR database is organic dyes and pigments followed by mineral pigments.  Raman spectra are currently being collected and added to the database.

Suzanne also stressed the growing use of IR and Raman data use in the field and how this is being reflected in papers at IRUG conferences specifically related to art and archaeology.  She provided examples in which mineral pigments as well as synthetic organic pigments have been identified though used of the database and how Surface enhanced Raman spectroscopy (SERS) can be used to overcome the problems of fluorescence by using nanoparticles to magnify the signal.

Objectives of the IRUG database will include a website interface with the ability to upload data by users, software, a translator to transform native data into IRUG standard, a searchable library, an interface for keyword searches, data download, and spectra printing.

Suzanne is chair of the newly formed Raman review committee, which reviews spectra and format.  The format to be used by IRUG is JCAMP-DX (ASCII) files for universal access.  This will also allow batching of spectra for submission.  To learn more about the format refer to the IRUG website.

The first batch of spectra has been pledged but the invitation is open to new contributors.  Interested people should contact Suzanne or Beth Price, the project manager from the PMA.  Currently users cannot upload data but can do searches on the website.

A comment after the talk reminded the audience that it is a free database though users need to contribute 10 spectra to get access to the searchable version.

39th Annual Meeting – ECPN Portfolio Session, Thursday, June 2, 10-10:30am and 3-3:30pm

ECPN Portfolio Session at the 39th Annual AIC Meeting

The Emerging Conservation Professional Network (ECPN) organized the first graduate student portfolio session ever sponsored at an AIC Annual Meeting. Graduate students in conservation programs from the University of Delaware, New York University, University of California Los Angeles, and Buffalo State College presented their portfolios to a packed house of attendees during both the morning and afternoon sessions. In all, over 80 individuals attended the two sessions.

The graduate students volunteered to exhibit portfolios representing their cumulated experience as either a first-year, mid-term, or graduating student in art conservation. The portfolios highlighted their treatment experience and professional training; including reports, photographs, and research projects. The participating students were available to address any questions attendees had and to offer advice and information to those interested in pursuing a graduate education in art conservation. Attendees included pre-program students, current graduate students, emerging professionals, and AIC professional members and conference attendees who were curious about the work graduate students are doing.

The portfolio sessions were a tremendous success and we look forward to the opportunity to make this an annual event at the AIC meetings. ECPN would like to extend our deepest gratitude to the following students for participating in this initiative and making it such a wonder experience for all:
Buffalo State College – Genevieve Bieniosek, Kari Kipper, and Rebecca Summerour
New York University – Julia Sybalsky and Maggie Wessling
UCLA/Getty Conservation Program – Tessa de Alarcon and Dawn Lohnas
Winterthur/University of Delaware Program in Art Conservation – Sarah Gowen, Laura Hartman, Gwen Manthey, Carrie McNeal, and Elena Torok

To read and contribute your comments on this event please visit ECPN on Facebook or our Blog.

39th Annual Meeting – Notes from an Emerging Conservator

I am a third-year fellow in the Winterthur / UD Program in Art Conservation, and this year’s annual meeting in Philadelphia was my first. I was amazed at the sheer size of the conference, the number of conservators, students, scientists and educators present, and at the expanse of topics discussed during the talks. As bewildering as the event often felt, it was wonderful to be able to engage in conversations with friends and colleagues. I was extremely impressed with the strong presence of emerging conservators, especially the many pre-programmers who ventured to Philly. It was equally inspiring to watch the many leaders in the field present at the meeting share their expertise, and engage in discussions with young professionals.

As with any new experience there were many surprises. I did not realize how much I would regret not having a business card – everyone, pre-programmers, students, and recent graduates should have one. During the meeting I had the opportunity to deliver a talk, and while I felt prepared in the moment, I was surprised at the amount of interest people showed when I was approached with questions afterward. I am very glad that the talk – as well as those delivered by two of my classmates – were so well received. It showed me that student research has a place at AIC conferences, and is valued by many in our profession.

I am so grateful for the opportunity to attend this year’s AIC meeting, which would not have been possible without the support of the FAIC George Stout Grant, as well as the gracious hospitality of two of my WUDPAC classmates. It was inspiring to see many conservators at so many levels in their careers together in one venue, and to observe such an active exchange of ideas between them. The online tools that enable this exchange are helping us make the most of the collaborative relationships we build at these conferences. It would be great to see the debates raised during the general and specialty group sessions continue on some of these available platforms – including the AIC and ECPN blogs, as well as the email distribution lists (which, I have heard many say, would benefit from an inter-specialty-exchange of ideas).

39th Annual Meeting – Joint Paintings/Research and Technical Studies Session, Friday June 3, “Microclimate and Anoxic Frames” by Judith Bannerman

Judith Bannerman and a team of researchers at the Tate, London have been developing microclimate frames to reduce fading and preserve sensitive works of art, particularly photographs and works on paper.  While we know that light fades materials and low-oxygen environments can reduce this phenomenon, the research team set out to design a functional microclimate frame and then measure the impact of various environments on sensitive works of art.

First, the microclimate frames were introduced; the frames are designed to be versatile, compact, reusable, and fit into existing installations and frames.  Following a conference at the Tate in September, 2011, the frames should be commercially available through KeepSafe Microclimate Systems in 3 sizes: A1 (841 x 594 mm / 33.11″ x 23.39″), A2 (594 x 420 mm / 23.39″ x 16.54″), and A3 (420 x 297 mm / 16.54″ x 11.69″).  The frames allow for easy access to the gas valves and artwork for unframing while maintaining a good seal through a sandwich design with the use of elastomer “o” rings.  Questions were raised about the composition of the elastomer and adhesives used in the frames, and while they could not be disclosed at this point, Judith assured that more technical information would be available after the patents are finalized.

With their prototype frames, the Tate began to study the impact of various oxygen levels and relative humidities on the fading of various art materials.  Three oxygen levels were chosen: air at 21% oxygen, hypoxia at 4-6% oxygen, and anoxia at 0-1% oxygen.  Temperature and humidity (at 40% and 50% RH) were monitored inside the frames during testing, and a microfadeometer with a 0.4mm spot size was used to study the accelerated fading of various materials.  Generally, when the oxygen level was brought to 5%, the fading was halved for most materials at both 40% and 50% RH, but at 0% oxygen some materials improved slightly while others faded more.  The study determined that 5% oxygen at 40%RH was best for a work on paper with iron gall ink and a dyed basket, and 0% oxygen at 50% RH was best for the digital photographs tested.  Some composite objects, like the iron gall ink on paper, required a compromise since one set of conditions might reduce the fading of one component but increase the fading of another.  During the question period, someone mentioned that some pigments fade more rapidly in anoxic conditions, so it is important to remember that conditions should be carefully considered for each object.

Future topics of research include studying long-term display or storage in the microclimates and pressure-testing the frames.  They may also develop larger cases for objects, but at this time the three frame sizes are slated to be available in September.

39th Annual Meeting – Architecture Student Session, 6/2/2011, 9:40AM-10:40AM

Following my own presentation in this session, I had the privilege of listening to my colleagues at Columbia University and the University of Texas-Austin discuss their research on architectural conservation material issues.

Sarah Sher (Columbia) exposed the design theory behind soiling on Marcel Breuer’s buildings through conducting an elaborate study of his personal writings and lectures.  She challenged conservators that approach Breuer’s structures to view the soiling as significant to its overall design aesthetic, because it was intentional.  For Breuer, reinforced concrete was the ideal material- requiring little to no cleaning (as opposed to its glass/steel counterpart), and that soiling in fact enhanced the aesthetic of the architecture “to aid in the process of aging.”  In the section of her presentation entitled “Designing the Aging Process,” Sher focused her discussion on Breuer’s Cleveland Trust tower.  Breuer anticipated heavy soiling on the structure, quoting the effects of polluted Cleveland air.  He designed for this effect, which he believed allowed shadowing and depth of the surface.  Sher ended her talk with Riegl’s conception of age value, and the questions that modernist pose for conservation interventions.  With a fascinating talk, Sher introduced research into a field that will need to be expanded and better understood as we are increasingly working on modernist and Brutalist structures.

Sarah Caitlin von Hedemann (Columbia) presented her thesis research on current cleaning formulations for removing biogrowth on stone, utilizing a newly manufactured Prestor gel.  She utilized laboratory testing, as well as field tests on sites around the city of New York, including 1- Wallace limestone (facade of the Metropolitan Museum of Art), 2- Indiana limestone (exterior of The Cloisters museum), 3- Texas limestone (Bronx Victory Memorial), 4-Tuckahoe marble ( Lagrange Terrace, Delbarton School), and 5- Carrara marble (Portrait Bust, Delbarton School) –if I mislabeled or misunderstood any of these stone types, please comment to correct me!  Utilizing analytical tests ranging from XRD, SEM-EDS, FTIR and GC-MS, she tested the products’ effectiveness and the presence of residues left by the cleaners.  von Hedemann concluded with her recommendations:  Prestor gel should be used for less porous stone, as it had atendency remove porous stone surfaces, CB-4 requires more research but was overall ineffective and left larger residues, BioKlean was successful but this might be due to its 2-step process and it is considered very agressive and alkaline, and D-2 and BioWash had average cleaning capability.

Payal Vora (UT-Austin) studied as a Materials Science engineer in her undergraduate education, and became interested in preservation efforts following natural disasters.  Her thesis is an extension of this interest, as she conducted a study of masonry cleaners for Fort Livingston, LA following the 2010 Gulf coast oil spill.  The fort, located on Grand Terre island is the only occupied barrier island in Louisiana, and has been greatly affected by the spill due to erosion issues that allow parts of the fort to remain underwater.  The unprecedented contamination of the spill, required a technical study to guide conservation efforts, and this was spear-headed by NCPTT and UT’s Architectural Conservation Laboratory.  Unable to remove original material from the fort, NCPTT provided contemporaneous brick (from a demolished early 1900s home) as samples for Vora’s study.  Developing her experimental design,Vora prepared her samples according to ASTM C-67-09, she developed a method for soiling the samples, and conducted artificial weathering with an Atlas C-4000 Xenon Arc Weather-oMeter on the brick Q-series.  On the U-Series, samples were unweathered, but placed in an oven for 8-10 hours to ensure samples were dry prior to cleaning.  Cleaners were chosen from the National Remediation Plan’s list of approved cleaners for the Gulf Coast spill- the 6 final choices were Petro-Clean, Cytosol, SC-1000, Gold Crew, De-Solv-It Industrial Form and De-Solv-It APC.  Cleaning was evaluated using telecolorimetry and a visual inspection survey.  Responding to a national crisis, the project represents an important effort in disaster relief for historic structures.

It was a pleasure to hear about the incredible work being done by emerging professionals in this field!