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.

42nd Annual Meeting – Engaging Communities in Collection Care Session: “Current Conservation Education and Practice: Are They Sustainable?”

The topic of sustainability was on everyone’s minds at the AIC 42nd Annual Meeting, and an evaluation of the sustainability of our own profession and its educational path was part of the program. Having recently crossed the threshold into an art conservation graduate program, I was particularly interested in hearing Paul Himmelstein, a private practice conservator and partner at Appelbaum & Himmelstein since 1972, assess the sustainability of such programs.
In order to better understand how the graduate programs have changed over time, Himmelstein opened his talk with summaries of answers to a questionnaire he had distributed to the nine members of the Association of North American Graduate Programs in the Conservation of Cultural Property (ANAGPIC). From the responses collected, he reported the following:
–       Most applicants today are female, compared to earlier ratios of applicants, who were closer to 50% female and 50% male.
–       The requirements for admission have increased, both in the number of required pre-program hours of conservation experience and in the number of pre-requisite courses.
–       All programs require two years of General Chemistry and Organic Chemistry.
–       All programs are cost-free regardless of need.
–       Most applicants apply twice before acceptance.
–       Approximately 80 students apply per year.
–       The number of accepted students in each program has remained the same.
Himmelstein attributed these changes to a list of reasons. He surmised that the decreased number of male applicants is a result of the increased number of academic requirements and pre-program hours of experience. Men, he said, are more deterred by the extra years needed to complete these requirements as they are still driven by the “provider” mentality. He also noted that AIC is currently 66% female, but the majority of conservation leadership positions at major fine-arts institutions are held by men. He also pointed out that the majority of our demographic is white and middle-class. In response to the full-ride fellowships, Himmelstein predicted that the expense of supporting all students every year is not sustainable, given the number of students accepted.
Himmelstein continued by offering a list of proposed solutions. He suggested considering changing the grants to a need-based system. He also suggested adopting an admissions approach that simply rejects or accepts with no option for reapplying, as in medical schools and law schools. He also added that more men are entering the field of nursing, another female-dominated profession, as a counterpoint to the fact that our profession is losing men.
After stating that 50% of AIC members are in private practice, he advocated for a business-management component at the graduate level, in which conservators in private practice could share their experiences and provide mentorship at the post-graduate level. He said that new graduates “just aren’t ready” to begin careers in private practice. He also advocated for Kress scholarships for textbooks.
His solutions list continued to broaden outside the graduate school realm and included general suggestions for advocacy and outreach. According to Himmelstein, “Met[ropolitan Museum of Art] conservation projects are boring” and “conservation is hidden.” He feels that conservators are not working as important colleagues with other museum professionals; they also need to play a larger role in the fields of art history and archeology. He suggested presenting conservation treatment projects online, as in plastic surgery “before” and “after” shots. Viewers could scroll over the artifacts to watch them change. Himmelstein suggested that the public “expects us to be wizards,”and concluded with the statement, “We are not on a sustainable track, but I think we can be.”
Assessing the sustainability of our profession, especially in our current economic climate, is imperative. I agree that we must reexamine the number of students graduating each year to reduce expenses and to help control the job market, but not by selectively limiting funding or reducing a person’s chances for acceptance. Limiting funding at the graduate level would create an impossible financial position for most students. The demands of graduate school are such that no one is able, or even allowed, to work while in school. Unless a student is independently wealthy, then everyone falls into the “needs funding” category. According to Himmelstein’s report, average conservation students are not independently wealthy. Many internships at the graduate level are also still unpaid or partially paid, and students rely on their stipends to compensate. The current post-graduate income can also not sustain significant student loans. The “one strike you’re out” formula is also flawed. Many talented individuals who have made great contributions to our profession would not have become conservators if they did not get another chance to apply. Those who reapply show tenacity and dedication and our profession is shaped by those who participate.
I believe the decrease in male applicants is related to other factors and not because of the program requirements. Nursing is likely attracting more men because it has lost some of the “stigma” of a woman’s profession along with providing a relatively secure and well-paying job market. Conservation wages have fallen over time and the number of men in the field are likely reflecting this trend. In another life I pursued a degree in nursing and can attest that the increase in the number of men is not because less time is needed to get in to school. On the contrary, regardless of whether a student works to earn a bachelor of science in nursing or an associates degree in nursing, many hours of volunteer experience are required and many programs now require that a student become a certified nursing assistant before admission. This certification takes two months of full-time work or six months of part-time work in order to qualify for the state board exams. This work, in addition to the pre-requisites needed to apply, takes most individuals at least one year before they can apply to a nursing program. Some of the struggles we fight in conservation are not unique, but we are feeling the growing pains of a smaller and much newer profession, one that needs continuous advocacy in order to earn a living wage.
I agree that continuous outreach, both to the public and to colleagues in the humanities and sciences, is essential. Himmelstein touched on disseminating information to appropriate departments within schools. This is a particularly important task for me as a current graduate student, and a great way to continue advocacy for our profession. I was made fully aware of how important it can be to connect with other graduate students in the two weeks that followed AIC. From June 2-13, three classmates and I participated in the Delaware Public Humanities Institute (DelPHI). Applications to the course were open to all University of Delaware graduate students who work with material culture. Those two weeks were packed full of learning important skills such as navigating social media and presenting your project with concise and interesting language, and investigating what inter-departmental collaboration could mean for each of our disciplines. Plans to attend one another’s lectures and to share our research in one another’s classrooms are already underway for the 2014-2015 school year. I would like to hear other examples of these types of collaborations, because I am sure other wonderful ideas are being implemented.
The sustainability of art conservation is indeed an important discussion and I hope it is one in which conservators at all stages of their careers will participate.

42nd Annual Meeting- WAG Session, May 31, “Lost for One Hundred Years: The Conservation of a Unique Polychrome Neoclassical Pulpit in Upstate New York” by Alexander M. Carlisle

Alex Carlisle presented a fascinating and detailed treatment of the pulpit in Fort Herkimer Church, German Flatts, New York (http://fortherkimerchurch.org/7.html). The church has a long history; the current structure dates to 1767, with many additions and expansion in war and peacetime.  The pulpit was added in the early 19th century, and seems to be completely unique; it is made from white pine, but nothing is known about the workshop.

Pulpit image: http://www.mohawkvalleymuseums.com/fortherkimerchurch.html
Pulpit image: http://www.mohawkvalleymuseums.com/fortherkimerchurch.html

During a recent, major renovation of the church, white paint coating the pulpit was partially sanded off and discovered to be covering polychrome decoration. At this point, Carlisle was asked to work on the project, to remove the remaining white overpaint and preserve the original polychrome layer. At least one coat of white paint was lead-based, and very intractable; the majority of this was mechanically removed. Fortunately an older resin coating layer was present, and the lead white paint tended to cleave off at the interface.
Once the white overpaint was removed, the remaining original surfaces were consolidated and coated with a barrier layer. Losses in the polychrome ornament were inpainted to re-create the original decorative effect.  So far the base and main section of the pulpit have successfully been treated; the canopy awaits funding to complete the project (keep an eye out for part 3!)

42nd Annual Meeting- WAG Session, May 29, “What Lay Beneath – Revealing the Original Exuberant Painted Decoration of an 18th century Painted Pennsylvania German Shrank” by Scott Nolley and Kathy Gillis

Nolley and Gillis treated a 17th century Pennsylvania German shrank which is a rare example with surviving original painted finish including faux burl wood graining and colorful decorative ornaments.
Shrank is a German word for wardrobe; many such cabinets were made in America by immigrants, using locally available woods. As with other types of furniture, these would sometimes have been faux painted to imitate a fancier wood with more elaborate carving or decoration; grain painting was a common decorative technique. Due to their utilitarian nature, original finishes on early examples seldom survive.
Cross-section analysis showed that the Chipstone shrank did have original paint, but with large areas compromised by fire damage and wear from use. This led to the initial overpainting in the early 19th century, followed by several consecutive paint treatments over the years, including an opaque, gray-blue colored casein based paint. This gray-blue layer proved to be very intractable, particularly over areas that were burned or highly worn. Cleaning solutions with chelators were able to remove the majority; agar gel was used for local cleaning around sensitive areas. Older oil-based coating layers actually acted as a resist to prevent the cleaning from going too far.
Completed with varnishing, waxing, and selective inpainting, the treatment was able to successfully expose original decoration and give a sense of the shrank’s intended appearance.

42nd Annual Meeting- WAG Session, May 29, “Roccoco Drama – Dry Ice Cleaning the Ormolu Mounts of the Augustus Rex Writing Cabinet” by Catherine Coueignoux

Catherine Coueignoux presented an exciting treatment of the Augustus Rex (c.1750) writing cabinet in the collection of the Victoria & Albert Museum (W.63-1977 http://collections.vam.ac.uk/item/O74665/writing-cabinet-kimmel-michael/# )
The elaborate ormolu mounts had been previously re-gilded. Before treatment were coated with a thick layer of dirt and dust over a shoe polish-like wax treatment, which was possibly added to dull the appearance of the bright new gilding.  All other metal components were corroded, and the wood and marquetry had all been stripped and refinished. Curators wished the treatment to result in a bright, nearly-new appearance as it may have looked when newly restored (the previous refinishing and regilding probably occurred while owned by the Rothschild family).

The Augustus Rex writing cabinet was made c.1750 for Augustus III, Elector of Saxony, possibly by Michael Kümmel, based in Dresden. The Victoria & Albert Museum acquired the cabinet in 1977.
The Augustus Rex writing cabinet was made c.1750 for Augustus III, Elector of Saxony, possibly by Michael Kümmel, based in Dresden. The Victoria & Albert Museum acquired the cabinet in 1977.

Spotty corrosion on metal components that could not be removed was treated locally where possible. EDTA gel and BCA gels were tested but unsatisfactory- cleaning not enough, or too well. Coueignoux was able to use rottenstone to spot clean dark areas, leaving a layer of light corrosion sympathetic to surrounding areas. In some places, the corrosion spots were left untreated.
The removable ormolu mounts were cleaned using dry ice pellets, a new method for the lab. Their system uses a block of CO2 dry ice which is shaved into pellets and sprayed onto the surface of the object using an air compressor with a custom nozzle. The CO2 pellets expand on contact, providing a gentle mechanical cleaning. By moving quickly along the surface, they were able to avoid excessive cooling that would result in condensation. Acetone and a hairdryer were on hand to remove any condensation that did form. Other labs using CO2 cleaning include the Getty and the Smithsonian.
In the case of the ormolu mounts, CO2 cleaning was fast, safe and effective and removing the unwanted wax and dirt- 150 mounts were cleaned in only seven hours! Obviously this method is not appropriate for many objects and materials, but may be a convenient choice for more conservators in the future.

AIC’s 42nd Annual Meeting – Opening Session, May 29, “Sustainable Collections Care on a Budget – A new museum store for Bolton, UK” by Pierrette Squires

With her excellent talk, British conservator Pierrette Squires showed that it is possible to do a major collections move project while still being economically and environmentally conscientious.  Of course, doing so required an enormous amount of careful planning, creativity, and hard work, which Squires outlined.
Situated in northwest England, an area hard hit by the recession, the Bolton Library and Museum Services (http://www.boltonmuseums.org.uk/) sold the textile mill which previously housed its collections storage.  The staff then had to move and rehouse the collection of over 40,000 objects, ranging from fluid specimens to industrial machines, to a new location in two years and with a tight budget of $1.4 million.  A large part of the success of the project resulted from the conservation team being included from almost the very beginning.  Because of their involvement, the move was inspired by the green values of “Reduce, Reuse, and Recycle,” values which contributed not only to environmental sustainability but economic sustainability as well.
The location chosen for the new collections storage was another old factory.  Despite some pollution and asbestos, the building was in good shape structurally.  Working closely with the mechanical engineers, the museum did careful environmental monitoring of the space.  The museum made the unorthodox decision not to install air conditioning, which would be expensive, but instead to use large amounts of insulation.  Other green features of the building renovation included the installation of solar power panels and of Power Perfectors (voltage optimization devices), which save money by buffering energy draw.  Adjustments like these resulted in a 50% reduction in energy costs.
Less expensive alternatives for outfitting the storage area were also sought out.  Rather than using an expensive system designed for museums, cheaper compact storage intended for use in other industries was selected.  Used metal racks and wooden pallets were chosen for storage of larger objects.  In all, 65% of the storage furniture was second hand, saving money and keeping things out of landfills.
The arrangement of collections within the storage area was also carefully planned to maximize the environmental conditions of the building.  For example, more stable objects like geological specimens were placed in areas against exterior walls, while textiles and archaeological materials were placed in areas farther away from the loading dock and thus most protected from temperature and humidity swings.  Fluid preserved specimens were placed in the northern and thus cooler part of the building.
The actual move of the collection continued the theme of sustainability.  Local transport companies were hired to do the actual moving, which saved on gas and contributed to the local economy.  Storage and packing materials were reused as often as possible.  When no longer usuable, materials were recycled.
In conclusion, the move was a very successful project.  Although not all the choices made in the project are applicable to every museum – one wonders about the risk of pollutants from used and wooden storage furniture, the ideas presented in this talk were interesting and thought-provoking.  The talk proved that environmental sustainability and economic sustainability are not opposites but can go hand in hand.

42nd Annual Meeting – Research & Technical Studies Session, 29 May, "A Closer Look at Early Italian Panel Paintings Session: Imaging Cross-sectional Paint Samples from the Walters Art Museum" by Zachary Voras, Kristin de Ghetaldi, Tom Beebe Jr., Eric Gordon, Karen French, Pamela Betts, Glenn Gates

A problem encountered in the study of paintings is distinguishing the medium in which they were created, and delineating layers which may include different media of mixtures of media. This was the subject of a paper presented at the Research and Technical Studies session.
It is not easily possible to distinguish between oil paintings and tempera (egg-based) paintings by eye, or using many analytical methods. The authors discussed the benefits and drawbacks to three main types of analysis that are used within paintings conservation: cross-sectioning, Fourier-Transform Infrared (FTIR) spectroscopy, and thin layer chromatography (TLC). FTIR, for example, cannot distinguish between egg proteins and glue, and the results can be masked by pigments or colorants. None of these methods, as discussed, can be definitive when it comes to mixtures of media such as tempera grassa.
The author also considered the effectiveness of other common methods, such as GC/MS (Gas Chromatography – Mass Spectrometry). The main drawback to this is that results cannot be compared across different experiments if the methodology varies even slightly.
The combination of these drawbacks in common methodologies led the authors to pursue Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), a high-resolution technique that is better at separating and identifying fragments which are different but have similar masses. It also allows for the presence of specific compounds to be ‘mapped’, giving a helpful visual of layers and levels. Using this method, they were able to map for amino acids, identifying the presence of animal glue in a mixture. Practically, this was shown to differentiate between a gesso-size ground and the glue layer which was determined to have been purposefully added.
The talk concluded with a reminder that this technology, as with most, works best in conjunction with other methodologies. While this is an important point to remember, the potentials of this technique are exciting. I’m very interested to see the potential that this technique has for three-dimensional objects with multiple painted or gilded layers. I hope that someone pursues this, and that the technique is able to be harnessed across conservation disciplines.

42nd Annual Meeting- OSG + RATS Session, May 30, “Blue, Red, and Wound All Over: Evaluating Condition Changes and Cleaning of Glass Disease on Beads” by Robin O’Hern and Kelly McHugh

Glass disease, weeping glass, glass deterioration, funky glass* (*author’s description)–just a few of the many names used to describe the degradation of glass beads that museums have observed as a white precipitate/cloudy appearance and/or cracking and splitting.  If you’ve observed this in your collection, take notice- Mellon Fellow in Objects Conservation, Robin O’Hern, is on the case.
O’Hern has taken advantage of the history of glass disease detection at the National Museum of the American Indian (NMAI) and begun evaluating how the different cleaning methods have fared over the years.  In 1999, Kelly McHugh (research supervisor and co-author) and Scott Carrlee performed a condition survey of the NMAI collection.  The collection was moved into a state-of-the-art storage facility after the survey, where the RH has remained constant, but at a higher level than recommended for glass pieces.  (The beads are present on composite pieces with hide, bone, shell, feather, hair, etc. and therefore the environmental controls must address as many materials as possible, not just glass.)  Some of the pieces were treated at that time, and others have been treated in the interim years.  Using the museum database, O’Hern found that 25% of the condition records that list glass beads as a material also list glass disease.  O’Hern has performed another survey, this time seeking to observe condition changes over the past 15 years in a selection of objects from the 1999 survey, to assess treatment technique (ie, which solvents worked best to reduce glass disease), and to discover susceptibility trends (which beads are the worst culprits).
To understand the beads, O’Hern provided background on history of use and manufacture.

  • Glass beads arrived after contact with Europeans in 1492
  • Pony beads were introduced after 1675
  • Wound beads were introduced after the late 17th century
  • Seed beads were introduced 1710-1840
  • Red beads were colored from copper in the 17th century, ruby red in the early 18th century, and selenium in the 1890’s
  • Blue beads were colored from copper or cobalt, but from 1640-1700, they were tin-rich
  • Beads can be made by pulling the heated glass, called “drawn,” or by winding heated glass around a rod, called “wound”
  • Glass is made from silica, alkali (to lower the melting point, but also makes it water soluble), and calcium carbonate (that turns to lime- it’s added to help stabilize the glass after the alkali)

There are several explanations for the cause of glass disease.  Too little or too much of the lime (part of the bead’s composition) may cause water to leach out of the glass matrix as ions that then form salt on the surface of the bead.  The environmental conditions, such as fluctuations in RH, or materials in proximity, such as semi-tanned hide, may accelerate glass disease.  As seen from the list above, the beads were manufactured over a range of time, in different ways, and in different places.
As you can tell, there are many factors to research when evaluating glass disease.  O’Hern addressed as many as possible while still managing the scope of the project.
Survey Results
Condition Change: By comparing condition of the beads today to past condition/treatment reports, 16% of the beads have more deterioration now than in 1999.  Measuring pH was used in addition to visual examination to determine condition.  Some beads that did not look bad had a higher pH (above 7), signaling glass disease.  Some beads that looked hazy did not have a higher pH, meaning no glass disease (perhaps hazy from manufacture).
Differing Manufacturing Techniques:  Wound beads have it worse than drawn beads–95% of wound beads have glass disease.  This could be because they have a compositional percentage of lime that is less stable.
Differing Colors: Black, red, and blue are the most disease-ridden.  O’Hern looked through the museum database and found that the entries with the most “glass disease” indicated had blue beads.  Blue beads are very clearly the “winner” of the glass disease competition, followed by red and black.
Treatment Techniques:  Here’s where it gets even more interesting.  The conservation literature and posts on the Objects Specialty Group list serve debate the use of three solvents to remove the salts on glass disease: water alone, ethanol alone, and a 1:1 water:ethanol mix.  By comparing the 1999 survey to her own results, O’Hern capitalized on real-time aging to observe how each solvent mixture fares over time.  Water-cleaned beads had a 50% rate of glass disease return; water:ethanol-cleaned had a slightly higher than 50% rate of return; ethanol-cleaned had the least amount of return at just under 50%.  However, when looking at the beads cleaned with ethanol over the same time period as those cleaned with 1:1 water:ethanol (removing the very oldest treatments), the rate of return for glass disease falls to 40%.
(Note: Acetone has also been listed as a solvent for cleaning glass beads, but since the NMAI doesn’t use acetone, it was not included in this research.)
Other Observations:
1. Measuring pH is essential because beads may look like they don’t have glass disease, but are actually more alkaline.  Measuring pH is also quick and easy- cut your pH strip to a small piece, slightly dampen it in deionized water, press it onto the bead for 3 seconds, and then determine any color change in the strip.
2. The most affected beads were those sewn onto hide, but the disease was present when beads were in contact with many other materials as well.
3. Although cleaning with ethanol is a better choice for long-term disease prevention, the solvent chosen should still depend on the substrate around the bead.
Advice from O’Hern:
1. Record treatment materials when removing glass disease.
2. Take BT and AT details of beads so you can easily compare for condition changes in the future.
3. Measure the pH of the beads… and RECORD THE RESULTS.
4. Have consistent monitoring of glass disease.
As an audience member, it’s always exciting to see a project that has results, especially on a topic that is not studied as extensively as it persists. This is definitely a postprint worth visiting for more details and results.
For other examples (and some “good” photographic examples), visit Ellen Carrlee’s project “What’s that White Stuff?” that she and (then WUDPAC graduate intern) Christa Pack reported on in Ellen’s blog: http://alaskawhitestuffid.wordpress.com/2011/08/09/glass/