41st Annual Meeting – Wooden Artifacts Session, May 31, “Schooner Virginia: Addressing Inherent Issues in Ship Restoration” by Nicole Wittig

As a furniture conservator who was fascinated by sailing ships in his childhood, and spent many hours carving and building ship models, I was eagerly awaiting Nicole Wittig’s presentation on the preservation efforts regarding the schooner Virginia, which is currently in a storage shed at the National Civil War Naval Museum in Columbus, Georgia.
Looking forward to the mechanics of a ship’s restoration, I soon realized that this talk was going to address a much more fundamental issue that conservators face on a near daily basis: what aspect of an objects history should be brought back, and how will that affect the viewer’s perception of the object. How should the Virginia, a vessel that was significantly altered over time, be restored and ultimately perceived?
Beginning her talk with a historic narrative, Ms. Wittig described Virginia as a sailing vessel built on the eastern shore of Mobile bay in 1865. Utilizing historical records, Ms. Wittig related how a series of ads appeared in 1866 in Mobile papers, mentioning ships of a very similar tonnage and description. She surmised that the Virginia was probably constructed not from plan, but by local master shipbuilders, and had been designed to service the region’s oyster fishing fleet. Decades later, in the 1930‘s, it was mentioned as one of four such vessels in the Historic American Merchant Marine Survey (HAMMS), and recorded as a fishing vessel now working the west coast of Florida. The Depression Era HAMMS endeavor was significant since it was designed to record the disappearing American wooden sailing fleet, before the such vessels would be replaced by ones built of metal with engine propulsion. As such, the survey went into great detail regarding Virginia’s physical description and included construction drawings and photographs. I was especially taken by a photograph of the schooner, which depict it with twin masts and sails. It immediately brought back memories of a challenging childhood project, to build an accurate wood model of a Gloucester schooner, and the many hours I lovingly spent carving masts and fitting thin cotton to simulate sails.
The Virginia continued its service as a fishing vessel in the Gulf of Mexico over the following years, and was discovered by the Coast Guard in 1967, naming it to be the oldest operating fishing vessel in continuous service. When retired in 1990, Virginia had achieved a remarkable 127 year operational career. It was then purchased by the National Civil War Naval Museum, in the desire to preserve the vessel as an example of a Civil War blockade runner. Ms. Wittig went on to mention that definitive documentation regarding this possible aspect of the vessel’s life has not yet been fully discovered.
The following portion of her talk was devoted to documenting Virginia’s overall and interior dimensions, which are a length of 55’, a breath of 14’, and a draught of 3’, considerably larger than any object this conservator has treated. One approach to this task involved the taking of hand measurements and producing Adobe Illustrator drawings. Another approach utilized Total Station, a terrestrial laser scanner, noting millions of exterior points, which then permitted one to create a 3D image of the vessel. Although this technique does not lend itself to measuring interiors, it was able to produce striking multidimensional images, as seen in Ms. Wittig’s Power Point presentation.
Virginia’s current condition was also noted. One of the major preservation issues that has developed since the vessel has been out of water since the year 2000 has been the drying out of the timbers. This has led to dimensional changes in the wood, such as the keel twisting, necessitating not only the vessel’s cradling, but also the drilling of holes through its breath, and the installation of long metal rods to stabilize the structure. Sections of wood exhibit splintering and dirt and debris are now found in the wood crevices, retaining moisture and leading to wood deterioration. Although Virginia is stored in a covered shed, metal components are degrading, such as the rudder, which exhibits gross corrosion, with the metal delaminating in sheet-like sections. What was immediately striking to this conservator was the apparent lack of an ongoing maintenance program for this vessel, permitting these conditions to fester.
The presentation closed with an outline of the various preservation choices and goals that will need to be decided upon. If Virginia is designated as a Civil War blockade runner, would that not disregard its long fishing history? Were it to be reconstructed to its sail configuration, would that not also negate its engine propulsion history? And if other choices are made, such as preserving it as the longest operationally running fishing vessel, where would the money for its preservation come from, if the Museum of Civil War Naval History decide to deaccession it? Noting these challenging issues, Ms. Wittig suggested basing any decision on the HAAMS survey, since it provided the most thorough and reliable documentation for the vessel.
The Q&A afterwards was lively, with questions regarding tracking the name of the vessel, Virginia’s possible Civil War involvement and conservation costs.
All in all, a welcome revisit to an aspect of my childhood!

41st Annual Meeting – Workshop – Integrated Pest Management for Collections

This was a full-day workshop taught by three excellent and complementary instructors, Pat Kelley (Vice-President, Insects Limited), Emily Kaplan (Conservator, Smithsonian National Museum of the American Indian), and Rachael Perkins Arenstein (A.M. Art Conservation, LLC).  The day was broken into four sessions:

  • Introduction to IPM principles (including physical prevention, policies and procedures)
  • Behind-the-scenes (and inside the nooks and crannies) tour and real-life demonstration of pest monitoring and trapping in the Eiteljorg Museum of Native American and Western Art

IMG_7781    IPM Eiteljorg walkthrough (7)

  • Presentation/hands-on quiz on pest identification

2013-05-29 14 39 47

  • Presentation/practice session on remedial infestation treatments

While the emphasis was on museum objects (specifically natural history collections), there were many good lessons learned that translate to my field of interest, libraries and archives, as well as to other cultural heritage repositories.  I highly recommend this workshop to anyone who has responsibilities in this area (I thought about writing “interest” but when it comes to bugs, that’s putting it a little strongly for many of us).  I’d like to see this become an on-going AIC workshop.  My only suggestion for improvement would be to expand the pest ID presentation, which sped by too quickly for my novice’s eyes.
Key takeaways:

  • There is a comprehensive and dynamic resource that pulls together almost all the IPM we would ever need: www.MuseumPests.net, a product of the Integrated Pest Management Working Group, which is an interdisciplinary and independent professional group that is informally linked with AIC and also the Society for the Preservation of Natural History Collections (SPNHC). An associated listserv, Pest List, gives amateurs a place to ask questions of the professional community, confirm ID of pests, etc.
  • A key guiding principle of IPM is to reduce the use of chemical pesticides for many compelling reasons, including personal health and safety, environmental impact, cost, effective prevention of (rather than reaction to) pest-related damage, and early warning/response in the event of an infestation.
  • IPM has to be a group effort that requires buy-in from a diverse group of stakeholders, including the highest levels of institution administration, the facilities managers, housekeeping staff, groundskeepers, security managers and patrol staff, pest management experts either within or contracted from outside the organization, curatorial/collection manager/registrarial and support staff, caterers and shop managers, exhibit designers, and human resources staff, as well as conservation/preservation staff.
  • Including IPM as a part of an overall risk management strategy may be a way to draw resources to its successful implementation.
  • Well-written, approved, distributed, promoted, and enforced policies and procedures are vital to a successful IPM program.
  • Species identification is crucial in order to  prevent/eradicate; it informs the feeding patterns, reproductive cycles, behavior, and environmental conditions that can be targeted/controlled to ensure successful trapping
  • Traps come in various shapes, sizes, and odors (pheromones are species specific, so you have to identify what you have before you purchase the pheromone trap).  A “blunder trap” has no pheromone or bait but is just sticky and is placed carefully in the likely path of a pest.  A pheromone lure with sticky trap mimics the scent exuded by a specific species of female to attract males.  Poisoned bait traps are also used, but you can’t control where the pest goes off to die.
  • IPM is a great field for sleuths and puzzlers; but sometimes the answer (i.e. the cause of the infestation) is elusive, so there are some cold cases.
  • Common museum pests are mostly moths and beetles, many of which look pretty similar to me so I’d need professional confirmation of my amateur ID; I’m going to seek out and cultivate a relationship with a local entomologist
  • Remedial treatments include isolation, temperature (heat and freezing), and anoxia (nitrogen, argon, CO2).  CO2 requires a pesticide license.  Pesticides and fumigation are the last resorts.  Heat treatments can be very cheap (black plastic bag in the sun, car with the windows closed on a hot summer day).  Do not use anoxia if you have Prussian blue pigments.
  • Freeze/thaw/refreeze is *not* necessary; just freezing for the right length of time will do the job
  • My own personal observation: squeamishness may diminish when you get up close and personal on a regular basis.

And here is a list of some of the products and equipment that they demonstrated (this is not an endorsement, just information sharing)

  • Door sweeps: sealeze.com
  • Copper gauze for stuffing holes: Stuf-fit
  • Landscape fabric: Geo Xcluder
  • Desiccating treatment for high-risk displays (i.e. food art): diatomaceous earth
  • Oxygen scavenger: Ageless
  • Films for air-tight sealing: Marvelseal (opaque) and Escal (transparent) or Aclar (also transparent) can be heat-sealed together
  • Cube of Marvelseal: Zer02 cube system
  • Current fumigants: sulfuryl fluoride and phosphene (need a license)
  • Other effective pesticide: boric acid, which is available loaded into a silverfish pack (corrugated board)
  • Microscope: The Professor, stereoscope, battery powered, by Ken-A-Vision, lowest price at B&H Photovideo (~$80)
  •   We didn’t walk away with samples of sticky traps, but I’d add those to this list if I had the brand names etc.

Selected recommended publications:
Florian, Mary-Lou. Heritage eaters: Insects and fungi in heritage collections. London: James & James (Science Publishers) Ltd., 1997.
Kingsley, Helen; David Pinniger, Amber Xavier-Rowe, Peter Winsor. Integrated Pest Management for Collections: Proceedings of 2001: A Pest Odyssey. London: English Heritage, 2001.
Pinniger, David. Pest Management: a practical guide. Cambridge: Collections Trust, [2009].
Pinniger, David. Pest Management in Museums, Archives, and Historic Houses. London Archetype Press, 2001 (2004 reprint).
Winsor, Peter; David Pinniger, Louise Bacon, Bob Child, Kerren Harris, Dee Lauder, Julie Phippard and Amber Xavier-Rowe. Integrated Pest Management for Collections Proceedings of 2011: A Pest Odyssey, 10 Years Later.  London: English Heritage, 2011.

41st Annual Meeting – Architecture Session, May 30, “Breaking the Cycle:the Role of Monitoring in the Watts Towers Conservation Project,” by Sylvia Schwerin Dorsch, Blanka Kielb, and Frank Preusser

Photo by Lucien den Arend
Photo by Lucien den Arend

The Watts Tower was created by Sabato Rodia from 1921-1954 and was constructed without the use of mechanical methods. It is composed of Portland cement, steel, ornamentation (glass, tile, stones, sea shells), wire mesh, and armature. Now a National Historic Landmark, the towers and other sculptures are showing signs of deterioration and material loss.  Beginning in 2011, the Los Angeles County Museum of Art (LACMA) and the City of Los Angeles collaborated to conduct a materials evaluation in order to update the conservation plan and identify a new maintenance routine. Initial observations and investigations identified some of the issues to be mortar cracking, loss of ornament, armature corrosion from past treatments, adhesive and cohesive failures, and incompatibility of repair materials (i.e.,hydraulic cement, Portland cement, and traditional materials). The conservators wanted to better understand what repairs were successful and new causes of deterioration.
Photo by Lucien den Arend
Photo by Lucien den Arend

The team established a hypothesis that included multiple contributing factors to the deterioration of the towers.  These factors included environmental concerns such as seismic and wind loads, but also thermal expansion, stresses, and moisture intrusion.  Adjoining materials with different rates of thermal expansion led to the eventual detachment of ornamentation.  With support from the UCLA engineering department, the team utilized displacement monitors to monitor the cracks in the tower.  The team also employed infared thermography to visualize the heat profile of the central tower while also using time lapse photography.  The results indicated that there was an uneven heating and cooling of central core.  In conjunction with the displacement monitors, a tilt meter, accelerometer and thermocouples were used to measure the displacements caused by the thermal loading.  It was determined that the central tower had a north tilt due to thermal expansion during the day.  The accelerometer data also showed an increase in vibration frequency with change in temperature.
Another concern were the wind loads caused by the Santa Anna winds hailing from the deserts in the months of October through March.  The winds caused ornament loss due to increase of movement and vibration.  It was also determined that new cracks formed and existing cracks widened and narrowed during wind events.  A dynamic wind sensor and weather station were used to monitor rain, temperature, humidity, and wind speed.  The sensors confirmed that wind and seismic activity affected the tower, tilting the tower in correlation with wind speed.  Two wind events in October 2012 and January 2013 corresponded with the base crack displacements.
The team concluded that it was necessary to accept that movement occurs and that re-treatment is necessary.  To limit the amount of necessary intervention, it was important to use flexible repair materials that allowed for  movement, such as elastomeric crack fillers.  Polymer modified mortars with lower modulus of elasticity and flexible adhesives for ornament would also allow for movement.  The treatment plan also included initiatives to slow the corrosion rate, increase the water repellancy and to modify the environment to provide a wind break northeast of the towers.  It is also necessary to re-scan the tower every five years to determine if long term displacement has occurred.
 

It’s not only digital-born art that has exciting challenges

On the front page of its June 10, 2013 issue (“below the fold” where the human interest pieces go), The New York Times published an article by Melena Ryzik (“When Artworks Crash: Restorers Face Digital Test”) about the issues and ethical problems that arise when digital or Web-based works of art need restoration. The catalyst for bringing the subject to the world’s attention was the Whitney Museum of American Art’s treatment of Douglas Davis’s work, “The World’s First Collaborative Sentence”.
While it is true that a great deal of innovative work is taking place in the field of electronic media, conservators who specialize in other media face exciting challenges too. If there are current projects in the more traditional arts which would lend themselves to front page rather than Arts section coverage, perhaps this is the time to build on the momentum of Ryzik’s article and bring them to The Time’s attention.

9th Biennial NATCC registration now open

Conserving Modernity: The Articulation of Innovation
The 9th Biennial North American Textile Conservation Conference (NATCC)
November 12-15, 2013

San Francisco, California
Registration for the conference, workshops, and tours is now open! Go to http://natcconference.com for a glimpse of the papers and posters to be presented and to register. Keep in mind that space is limited for workshops and tours, so be sure to sign up now!
Full conference registration includes:

  • Entrance to all paper and poster presentations at the de Young Museum in Golden Gate Park on November 14th and 15th, as well as refreshments and lunches.
  • The opening reception, which will take place in Jackson Square and is being co-hosted by the Lotus Gallery and Peter Pap Oriental Rugs.
  • The closing reception at San Francisco’s Asian Art Museum.

For questions, please contact Yadin Larochette: yadinl [at] gmail [dot] com
 

41st Annual Meeting- Closing Session, June 1, "The Great Debate: Topic #2 (Volunteers)"

The energy, audience participation, humor, and yes, snarkiness, at the second annual Great Debate at this year’s AIC Annual Meeting proved that this is an event that should definitely become a regular installment on the Annual Meeting schedule. After a rousing debate over Topic #1 (whether we should exhibit unstable objects as an act of preservation), the teams for Topic #2 took the stage to debate the statement:

 “While volunteers used on preservation projects often allow us to accomplish more work, they undermine our capacity to regularly employ conservation and collections care professionals.”

Arguing for the affirmative were Dawn Wallus, Rose Cull, and Kelly Keegan. Their opponents for the negative position were Beverly Perkins, Will Hoffman, and Michele Marincola. Moderator Richard McCoy (who wore a very dapper bow tie in honor of the “modified Oxford style” of the debate) made it clear that the event was a purely intellectual exercise, and that the opinions expressed by the participants did not necessarily reflect their own or their institutions’ views. It was clear by the energy in the room, however, that this topic represents a significant concern for many in our profession.

First up for the negative team was Will Hoffman, who began his argument by pointing out that the statement in question requires clarification before it can be considered. Hoffman explained that, though many institutions do use the kinds of volunteers that most of us were probably thinking about, such as pre-program interns and good samaritans who help with large tasks such as rehousing projects,we should all expand our idea of the “volunteer.” The speaker then cited examples of experts in other fields  who have volunteered their time and skills to help conservators with the things that we cannot do for ourselves, such as a hospital performing a CAT scan on a mummy. The opening statement also touched on the commonly held belief that many institutions simply would not be able to function without volunteers, and suggested that volunteer programs sometimes lead to employment for either the volunteers or for new staff members by demonstrating the need for personnel.

 Next, Dawn Wallus stepped up to the podium to set up the argument for the affirmative team. She began by declaring that even though she could hear a “puppy dying” somewhere in the distance, she and her team were still prepared to make a case against the use of volunteers in institutions. Wallus commented that while there are many good volunteers, there are also those who, despite the best of intentions, end up undermining the professional nature of our work (cue Wallus’s teammates holding up masks bearing the image of the unfortunate Ecce Homo fresco that was botched by a volunteer conservator in Spain last fall). The speaker also noted emphatically that there are laws in place that stipulate that non profit organizations cannot use volunteers to further their own agenda, and that any volunteer interns must be present for their own educational benefit only, and not to provide work for the institution.
 Next to the podium was Beverly Perkins for the negative team. She reiterated her team’s position that the presence of volunteers can lead to the creation of new staff positions- she even provided an example from her own institution. Kelly Keegan’s rebuttal for the affirmative team made use of the old adage, “Why buy the cow when you can get the milk for free?” Teammate Rose Cull followed up on her remarks by restating the argument about the legality of volunteer labor, adding that our use of volunteer pre-program interns creates a socio economic barrier to entry into our field.
 When the time came for audience questions, it was clear that the audience had much to say about this topic. Several people wanted to know whether the affirmative team would outlaw volunteers, or, more simply, how they would address the problem. Among a variety of answers, Rose Cull’s response stood out when she stated that all we have to do is to simply follow the guidelines in our own Code of Ethics. Beverly Perkins delivered a rebuttal in the form of a poll, in which the majority of the room declared that they do indeed follow these guidelines, as their volunteer programs exist for the purpose of training people and not in order to get work done. Other audience questions addressed issues of unskilled vs. skilled volunteers (which instigated one of many subsequent reappearances of the Ecce Homo masks), how to get into formal training programs without volunteering, whether data exists on the actual effect of volunteer programs on employment, and other issues. There was so much interest in the topic that the moderator eventually had to cut off the questions in order to allow time for closing arguments.
 After both teams had reiterated their points in closing arguments, the room was polled to determine the winner. Both teams appear to have been equally persuasive, and the debate ended in a tie. The end of the formal debate signaled the end of the conference, but it was clear from the conversations heard in the halls on the way out that it will not be the end of this very important discussion. Feel free to continue the discussion in the comments, but please remember to uphold the good-spirited nature of the Great Debate!

AIC 41st Annual Meeting – Research and Technical Studies Session, June 1, "The Role of Polyester Film Encapsulation – With and Without Prior Deacidification – On Paper Degradation by William Minter and John W. Baty"

William Minter and John Baty presented the results of this aging study of particular relevance to those of us working with archives and library materials. The hypothesis: “Encapsulated acidic sheets will degrade faster than unencapsulated sheets”. The question driving the testing was whether deterioration products from the paper can become trapped in the encapsulation, thereby accelerating further damage. In essence, do encapsulated papers “stew in their own juices”?  I, for one, certainly would have assumed the answer to be “yes”. But the use of encapsulation as a means of support for brittle and fragile documents beats lamination with cellulose acetate, as would have been the practice decades ago. What else is a paper conservator to do?
Here is how this study proceeded: Minter and Baty acquired different naturally aged papers for use in this study of the effect of sealing papers between film. The papers were typical of those in archives, including bond paper, ledger paper and “onion skin”. All were acidic prior to oven aging. To more accurately mimic natural aging, the temperature used during aging was 45°C instead of the more commonly used 60°C and papers were heated for a longer period of time than normal. The aging “oven” was a sealed glass box with a circulating fan, heating element (pad?), and saturated salt solution that maintained a moderate relative humidity. If you have never been in the market for an official accelerated aging oven, you may be surprised to learn that they cost a pretty penny; we’re talking 10k! Fortunately, this alternative oven was significantly cheaper, and performed very well, consistently maintaining both temperature and RH.
 The primary method of checking the papers’ deterioration was by measuring degree of polymerization with size exclusion chromatography. Shorter hemicellulose chains in paper samples after aging equate to loss of strength and flexibility in the paper, properties that were also measured and evaluated with fold endurance and surface pH.  Results showed that the encapsulated samples DID NOT age faster than the unencapsulated samples, contrary to the hypothesis! (Maybe some of you will sleep better at night having learned this fact?) I believe this test concluded after 33 weeks. If appropriate, It would be interesting to learn if an even longer aging period would yield the same result.
A second set of aging tests with the same papers revealed that either washing in magnesium carbonate or using a non-aqueous spray deacidification product prior to encapsulation would be equally protective of some papers. It is not known how long this protection would last, however.
This was a very relevant study, the importance of which can be well appreciated by many in the field of archives and paper conservation. A repeat study of a broader range of papers, (maybe photographic?) could also yield very interesting results. For me, this is an essential paper to file under “must read, and read again”.

AIC 41st Annual Meeting – Book and Paper Session, June 1, "Update on Digital Print Preservation Research: What We Have Learned So Far About the Permanence and Preservation of Digitally Printed Books by Daniel Burge"

Digitally printed books are still in their infancy, with the onset of personal, customized and on-demand publishing, made possible in part by the internet. As they have become widespread, the understanding of their aging characterestics must be understood. This is made more critical by the variety of techologies and materials used, as well as the fact that many of the books published may be very small editions, or even one-of-a-kind, as with photo books.
Daniel Burge explained the results of some of the tests performed by the Image Permanence Institute in Rochester. Their tests examined digital inkjet books printed with both dye and pigment inks and electrophotographic books printed with dry and liquid toners. The aging tests compared the humidity, heat, pollution, light, abrasion and water resistance of digital books to traditional offset printed books. These comparisons may be used to evaluate whether the books made with modern technologies need a different standard of care than is provided to older books.
These tests specifically focused on bound materials and are not to be used to evaluate the permanence of art/photo prints or single documents. One critical issue is the material used for the technology. Often, papers must be specifically prepared (optimized) with a coating suited to the printing process in order to improve print quality and permanence. The use of alkaline paper and recycled paper was found to be on the rise, and these could be factors influencing digital book preservation.
In general, the good news is that digitally printed books do not appear to require widely different preservation environments than traditional books. Although they are far more vulnerable to water damage, they generally have equal resistance to humidity, heat, and pollution as do traditional offset books. They also have better resistance to light and abrasion, compared to offset. The vulnerability to water highlights the need for more study and planning regarding disaster and recovery techniques for digitally printed books.
For more information, see the DP3 (Digital Print Preservation Portal) project website. www.dp3project.org

AIC 41st Annual Meeting – Textile Session, May 31, "Emergence of 'Antique' Synthetic Textiles by Ebenezer Kotei"

Ebenezer Kotei, Objects Conservator for the Hagley Museum and Library, provided an informative overview of the history and use of the earliest synthetic textiles. The earliest man-made textiles began with the production of Rayon, a silk-like filament, created in France in 1884 from regenerated cellulose. Rayon and the other early man-made textiles have come of age. Nylon, the first truly synthetic fiber, is now celebrating its 75th year. (An exhibit that focuses on the history of nylon is currently on view at Hagley.)
Although the name nylon was never trademarked, Du Pont produced other polyamide fibers for different uses, among them are Quiana, used briefly for luxury clothing, Kevlar for bulletproof vests, and Nomex, used as a waterproof barrier layer with the ability to transmit  vapor. Nylon fiber textiles are to be found everywhere; from women’s nylons, fine gowns, bed-sheets, children’s clothes, sportswear and uniforms, to parachutes and blood bags. It was by far the most widely used and successful of the first synthetic and semi-synthetics (as compared with rayon, acetate and acrylic).
Mr. Kotei points out that these materials have crossed into the category of antique and that it is time to focus on them and evaluate them more closely to determine how these materials have aged, rather than simply viewing them through the romantic lens of time. His concern is partly due to the fact that many of these early fibers in their very first synthesized formulations were Du Pont company creations, now part of the Hagley collection.  Although acrylic and nylon fibers appear to be quite durable, other textiles have vulnerabilities. Some examples of the problems occurring with man-made fibers are; Rayon is prone to mildew and silverfish; Spandex (polyurethane rubber) is prone to yellowing from heat, light and nitrogen gas.     
An Institute of Museum and Library Services grant has allowed for the evaluation of these early textiles in Hagley collections by textile conservators in order to identify recommendations on storage and care for these early textiles. Researchers may find additional information on DuPont fibers in the Hagley Library.

41st Annual Meeting – Research & Technical Studies, June 1, “Contemporary Conservation for Contemporary Materials” by Yvonne Shashoua

Attending a lecture by Yvonne Shashoua, Senior Researcher in the Department of Conservation at the National Museum of Denmark, was such a treat, since she is so well-known in the field of plastics conservation, and her session did not disappoint.  Her calm, precise, and very approachable speaking style was impressive as she covered a scientific discussion on her current research into cellulose acetate degradation and its interaction with gas absorbents.  Since she will be presenting her findings in upcoming journals, I will only briefly go over what I learned and what you missed at this Research & Technical Studies AIC session.
Shashoua began by reminding us that plastics comprise an increasing proportion of museum collections.  Since it is difficult to detect plastic degradation until it reaches an advanced stage, a preventative approach, by either removing the factors causing or accelerating degradation, is usually taken.   Gas absorbents (silica gel, activated charcoal, Zeolite 4A, and Corrosion Intercept) are frequently used in museum storage and display situations to create a microclimate by removing specific gases.  She discussed how these materials are used and how they absorb pollutants, which I found very interesting.
Focusing on cellulose acetate, Shashoua discussed the mechanism of degradation (and the breakdown by-product acetic acid) and how additives (plasticizers and fire retardants, which are weakly bonded within the matrix) migrate out ultimately ending in shrinkage.  She was curious why the degradation process even begins in a museum environment, which began her in-depth research project. Cellulose acetate, has been used since 1910, but by the 1960s could be found in many objects: imitation mother of pearl, cigarette filters, early Lego bricks,  movie film bases and rayon.  By conducting a systematic study on the adsorbents’  interaction with cellulose acetate, she has found some startling results.  The adsorbents in some cases did slow down the onset of autocatalysis, however some also adsorbed the plasticizer and/or flame inhibitor, resulting in damage.  Her results suggest that commonly used absorbents in museums are non-specific and ineffective for cellulose acetate and, by extrapolation, other plastics.  She did rate the adsorbents  on a sliding scale; so reading her more in-depth post-prints will be a good lesson and/or review for all of us.  All this is startling news!  An archival acid-free box might simply be the best defense.  Wow.  I cannot wait to read her in-depth post-prints and journal articles concerning this fascinating subject.