When faced with a budget dilemma for oversize mining maps storage, Amy Williams, project conservator at the University of Pittsburgh, asked herself “the $13,500 question:” Is there a benefit to using an archival 12” diameter storage tube core versus a non-archival 12” core wrapped with an isolating layer?
It would be easy to assume that archival cores were significantly better, well worth the extra $13,500. However, when faced with the substantial cost difference, Williams decided to conduct a scientific research project to determine the most cost-effective and preservation-friendly rolled storage system for the 5’ by 15’ maps of the Consol Energy Mine Map Preservation Project. She and her co-investigator, Dr. Catherine Stephens, presented their results on May 31, 2013 during the Research and Technical Studies Session of the AIC annual meeting.
If Williams and Stephens could prove that there was an acceptable, more affordable alternative to archival tubes, the news would be of great benefit to cultural institutions, collectors, and conservators. I was eager to hear their results.
Williams partnered with Stephens, Senior Research Scientist at the Art Conservation Research Center, Carnegie Mellow University (now at Yale University) for the investigation. They studied four types of tubes and six wrapping options suggested by conservators: no wrapping, polyester film, Tyvek, Marvelseal 360, heavy weight aluminum foil, and tissue paper buffered with 3.5% calcium carbonate. For the cores, they selected two archival tubes with different adhesives (sodium silicate versus a blend of polyvinyl alcohol and polyvinyl acetate), a non-archival core of kraft paper with an unidentified adhesive, and a Quik-Tube concrete pouring tube composed of recycled paper and a polyvinyl acetate/acrylic adhesive.
In the experiments, the maps were simulated by using Whatman #1 filter paper. The use of Whatman #1 paper versus historic papers was discussed in another 2013 RATS talk by Bill Minter and John Baty, “The Role of Polyester Film Encapsulation—With and Without Prior Deacidification—On Paper Degradation, Studied During Long-Term, Low Temperature Aging.” Minter and Baty chose historic papers for their research. I think it would add to our understanding if Williams and Stephens conducted a second phase of their research using commercially available papers or naturally aged historic papers to compare with the Whatman #1 results.
Their test samples, each consisting of a “map,” an isolating layer (or none), and a core, were aged at 90˚C and 50% relative humidity in an oven for up to 24 weeks.
The researchers’ first discovery was the unexpected impact of the adhesive, which caused staining on the tubes at the seam gaps between the narrow strips of paper comprising the tubes. This staining transferred onto the Whatman paper “maps.”
To prevent this problem, Williams recommended obtaining seamless tubes by asking the manufacturer to skive the edges of the paper. She also emphasized the importance of knowing the composition of both the paper and the glue of the cores.
I wonder how problematic the adhesive would be during a natural aging process or during a lower temperature artificial aging, and hope the researchers will consider exploring this in the future.
Williams and Stephens reported that the linen ties on the samples caused staining during the aging process. They switched to rare earth magnets, which caused no reported problems. Would a lower temperature during testing have prevented or reduced the problem with the linen ties? If this is a significant problem at all temperatures, linen ties may not be appropriate for rolled storage.
The experiment produced more unexpected results. The researchers evaluated the effects of the cores and isolating layers on the “maps” by measuring the chain scission of the cellulose, the yellowness, and the pH of the “maps.” I was surprised to learn that both the Tyvek and the Marvelseal 360 actively promoted degradation, yellowing, and a lower pH.
The aluminum foil, polyester film, and buffered tissue offered varying amounts of protection, depending on the type of core used. The best isolating layer overall was the heavy weight aluminum foil, and the best wrapper for the kraft tube was polyester film.
I wondered if the high temperature during aging might be responsible for the poor performance of the Marvelseal and the Tyvek, and whether the heat caused chemical changes within these two films. How much of the unexpected results overall was caused by the elevated temperature? Would similar results occur during natural aging at room temperature?
The researchers did speak about this issue. Stephens said that they chose the high temperature for artificial aging to ensure detectable changes, and stated that more research was needed lower temperatures.
From what I understood about the test results that Williams and Stephens presented, it seemed that wrapping a non-archival core with heavy weight aluminum foil could give comparable results to using an archival core. I would like to know more the amount of difference they saw, and hope they will offer a detailed discussion of this in their article about the research.
The results of their experiment have caused me to question my own assumptions about the storage materials we use. I hope Williams and Stephens will continue their valuable research, to determine what results are typical at lower temperatures and answer some of the other questions they raised during this first phase of the investigation.
Category: Specialty Sessions
Posts on talks that were presented as part of the specialty sessions at AIC’s Annual Meeting
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 – 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
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.
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.
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 – 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.
41st Annual Meeting – Textile Session, May 30, “New and Current Materials and Approaches for Localized Cleaning in Textile Conservation” by Elizabeth Shaeffer (co-authored by Joy Gardiner)
I had the pleasure of attending Elizabeth Shaeffer’s session exploring current and developing approaches used in the localized cleaning of textiles. Her fast-paced, well-delivered lecture provided a wealth of information on localized cleaning techniques from the traditional use of cellulosic materials (cotton sheets, blotter papers and cellulose pulps) to gel systems (both viscous and rigid). She then concluded the session with a more in-depth discussion on a sampler treatment followed by comparison charts on the different methods. I will not go into all the detail that she went into, but I will provide a brief overview. We all should look forward to reading her post-prints as they will provide a more in-depth discussion. Being an objects major with a subspecialty in textiles, I was excited to hear her talk, as the reduction of stains or adhesives is found in all conservation specialties including paper, objects and paintings.
Cellulose Poultices
Beginning with the use of cellulose poultices to reduce stains from a textile by capillary action during drying. Shaeffer described a treatment performed by Joy Gardiner at Winterthur, with whom she conducted a lot of her research, where a series of cellulose poultices assisted in the reduction of a tideline on the upholstery fabric of a rather fragile chair. The textile was dampened followed by blotter wicking for the initial removal of discoloration. Blotter wicking was continued until no more discoloration was removed. At this point, dampened cellulose pulp was used for better contact. The difference between the before and after images were dramatic; the treatment was quite successful.
Viscous Gels
Unlike cellulose poultices, gels are used to deliver cleaning solutions (which might include chelators and enzymes) with the added benefit of being able to limit the amount of solution to water-sensitive surfaces and to increase the solution contact time. Viscous gels still maintain a fluid-like property and can flow into the interstices of a fabric, which could make it difficult to remove. She discussed the thick application of a methyl cellulose (MC) poultice on a dye sensitive sampler. MC (50% concentration) can be made very thick and molded by hand into the desired shape. The residue question can be reduced by the addition of a barrier, but this also can reduce the efficacy. Enzymes can also be included in MC poultices and alpha-amylase is currently available in a pre-made system, the Albertina Kompresse. Additionally, lowering the concentration of MC with shorter application times and the application of sodium chloride to the rinse solution can reduce resides.
Xanthan gum, another viscous gel, was discussed and it’s unique shear force properties, which was interesting. When the gel is agitated on the surface of a textile, soils will be suspended in the solution phase and then trapped in the gel structure when the force is removed. Also, xanthan gum is compatible with non-water miscible solvents such as benzyl alcohol or tolulene. The gel structure has “pockets” in the network allowing oil in water emulsion. Reducing bleaches cannot be used as it will break gel. Be sure a buy “highly purified” xanthan gum. Consider adding a biocide, as it can grow mold.
Laponite RD was also covered briefly. The benefit is that it is compatible with bleaches since it is inorganic. Studies do show that residues left may cause discoloration, so the use of a barrier like gampi paper should be considered.
Rigid Gels
The first rigid gel discussed in the session was agarose, which is a product already familiar in conservation. When dissolved in heated water and cooled, agarose forms a rigid three-dimensional polymer network with pores. These pores can hold solutions and can be combined with chelators, enzymes and even water miscible solvents. Depending on the concentration of agarose used, the pore size will differ thus affecting amount of solution released, and therefore can be tailored for each treatment. Shaeffer described her experience with a chelating test kit developed by Richard Wobers with varying pHs. She found that on a test linen, the higher pH was more effective no matter what the chelator. When Shaeffer was an intern at the Philadelphia Museum of Art, she used this information along with the system that Laura Mina and Kate Sahmel developed for removing dye bleed, to remove discoloration of the ground fabric of a sampler. (Laura Mina and Kate Sahmel presented their treatment at AIC last year.) Shaeffer’s treatment was successful but very labor intensive since each small area was outlined with cyclododecane followed by the “cut to shape” agarose (with EDTA) gel.. Agarose is easy to manipulate and reusable, something to consider. Finally, gellan gum was quickly mentioned as a recently introduced rigid gel finding its way into the consideration of conservators.
In Conclusion
The comparison charts, when the post prints are released, will be good to review again, since so many types of techniques, solutions and recipes were only briefly discussed. In the post-prints, she will be discussing at greater length her research and treatments (including “recipes”). Elizabeth’s warm delivery tone allowed me to be swept away into an in-depth discussion of gels and poultices used in textile treatments. In this blog, I have seriously only briefly touched on the discussion. It was a topic that embraces not just the textile specialty group, but other conservation specialties. She hopes that some of the material discussed will spark our interest; encouraging us to share our findings as we proceed. I, for one, will be now be considering these materials into my “toolbox” of techniques!
41st Annual Meeting- Textiles + Wooden Artifacts Joint Session, June 1, “Two's Company: Supportive Relationships” by Nancy Britton
Nancy Britton presented several interesting examples of innovative upholstery treatments using carbon fiber support for the underupholstery. She also shared interesting discoveries from examining construction methods and written markings on multiples and sets of furniture from the same workshop and from the same collection.
The treatments used carbon fiber as woven “fabric” sheets which can be cut, shaped, and embedded in epoxy to create very strong, rigid supports for the upholstery layers above. Nancy has used the carbon fiber/epoxy matrix by casting it onto an ethafoam base, casting smaller parts to assemble, and making a one-piece shell. She also makes up flat stock to have on hand which can be cut and shaped more quickly than casting pieces.
Carbon fiber is also available in many other forms from numerous suppliers, including a sandwich board similar to honeycomb aluminum panels, available from the company Protech: http://www.protechcomposites.com/categories/Sandwich-Panels/ (Please note, I am not aware if this specific product is suitable for conservation use.) More information on carbon fiber is available over on the wiki: http://www.conservation-wiki.com/wiki/Carbon_Fiber
Next, I was very interested to see and hear how Nancy examines pieces, and all the information that can be gained even from a bare, deupholstered frame. By looking at the tool marks, hole patterns, and remaining hardware, she has been able to see differences in working method that she feels indicate the work of different craftsmen. One set of furniture she examined had identical materials but differences in working style that suggest they were made in the same shop and time period, but upholstered by different people. Variations in the stitching also provide clues.
Finally, Nancy showed examples of markings (numbers) found on chair frames and upholstery layers of pieces from the Met’s Hoentschel show at Bard Graduate Center. By looking at the marks and comparing them to early photographs of installations at the Met, along with other exhibition information from the archives, she was able to learn more about the upholstery timeline and how the chairs looked in the past.
Nancy’s talk reminded me that careful documentation of an entire piece, down to the smallest and apparently insignificant details, can provide a wealth of knowledge. We may discover new information about the piece’s history, and learn more about past upholsterers, who remain largely unknown.
41st Annual Meeting- Textiles + Wooden Artifacts Joint Session, June 1, “Slipcovers: Old and New” by Anne Battram
Anne Battram presented a shortened version of a talk given at the “first International Conference in Europe focused on upholstery history,” held in Vadstena, Sweden. Proceedings of the Sweden conference, “The Forgotten History- Upholstery Conservation” ed. Karin Lohm are available from Linköping University. Several people noted that this publication can be difficult to obtain- check with Anne or the University. Archetype may also have copies.
The talk gave an introduction to the history of slipcovers in America, and was jam-packed with specific examples and great visuals.
Anne explained that slipcovers have been used for seating furniture, footstools, and tables. They are often used to protect the surface below, which might be an expensive or fragile upholstery fabric, underupholstery, or finished wood. In a home, sturdy slipcovers might be removed to create a fancier appearance in honor of an esteemed guest. But in some instances, the slipcover itself is made of an expensive, extravagant material, and can be removed and stored when not in use. One example of a close-fitting, fancy slipcover was secured to the chair using cords attached to the cover, threaded through holes drilled in the frame.
Adding slipcovers to worn or outdated furniture has been used as a less expensive alternative to having them reupholstered. Slipcovers also allowed rooms to be re-decorated “en suite” with matching fabric for the upholstery, cushions, and window treatments.
Slipcovers are differentiated from dustcovers, which are used to protect furniture when it is not in use (e.g. in storage or when a house was closed). Dustcovers tend to be less form-fitting, usually extend all the way to the floor, and often are made from solid colored fabric.
Striped and checked fabrics were popular for slipcovers used to protect upholstery from everyday use. Sturdy chintz and toile patterns were also common. Colonial Williamsburg has an example of a leather slipcover.
Construction details vary: some examples of early slipcovers were made with the seams facing out and bound, (giving an appearance similar to welting) which would make the fitting process simpler and add definition to the final shape. Some slipcovers are very loose, barely fitted and might be attached with ties. Skirts and flounces added to a slipcover would give added protection to projecting curved or carved legs.
Check out the postprints, and the proceedings from the Sweden conference, for all the well-researched details on slipcovers.
41st Annual Meeting – Architecture Session, May 30, "An Evaluation of the Conservation History of Chagall's Les Quatre Saisons," by Jamie Clapper Morris
Jamie Clapper Morris, an associate at Wiss, Janney, Elsther Associates, Inc. presented this paper on behalf of Deborah Slaton, principal at Wiss, Janney, Elsther Associates, Inc. and herself.
Les Quatre Saisons is a mosaic by artist Marc Chagall, which is exhibited in a public plaza in the Loop district in downtown Chicago. It was a gift from Chagall to the people of Chicago in 1974, and it is located at the Chase Tower Plaza (formerly First National Bank of Chicago Plaza). The mosaic has tesserae placed on precast concrete panels with more than 250 colors. It was constructed in the Byzantine Style and assembled in southern France.
The original maintenance on this piece included biannual cleaning and annual sealing with silicon sealant. In 1988, the roof of the mosaic had completely deteriorated with 25% loss on the west side. In order to repair it, granite panels were put on the roof. In places where tesserae had fallen off, they were reinstalled in slightly different way in order to distinguish it from the original. In 1993, a bird deterrent gel was added but then removed because of staining. Visual assessment and lab studies were performed, including chemical analysis and scanning electron microscopy studies. The majority of the distress was on the west side. From 1995 to 1996, repairs were being performed on the adjacent plaza, and the mosaic was protected with an enclosure. A protective canopy was built for the mosaic, and wind tunnel studies were performed to ensure maximum protection. When repairing the mosaic, a lot of tesserae from the roof were used. The canopy was finished in 1996.
From 2009 to 2010, facade cleaning and limited condition assessments were performed, including some sounding and field microscopy. Expected distress was found. In 2011, a more detailed assessment was performed and it was sounded at 100% with xylophone mallets. Some expected distress included efflorescence and mortar loss. Limited maintenance was performed, including removing general atmospheric soiling, graffiti, and bird deterrent (which didn’t work). It was surface cleaned, and the graffiti was removed with acetone and water. Areas of loss were repaired and tesserae were re-installed. Ongoing maintenance is recommended.