The fourth presentation of the Book and Paper Group session examined neither a book nor an object on paper, but instead a print on plastic: Roy Lichtenstein’s 1964 Sandwich and Soda, a screenprint in red and blue ink on plastic. The object occupies a sort of conservation no-man’s-land: it’s a print, so it’s not something an objects conservator would normally deal with, but it’s on plastic, which is not a paper conservator’s area of expertise. Marion Verborg, Craigen W. Bowen Paper Conservation Fellow at the Straus Center for Conservation and Technical Studies at Harvard Art Museum, jumped into the void with this print on plastic, part of the portfolio X + X (Ten Works by Ten Painters), published as an edition of 500 by the Wadsworth Athenaeum in Hartford, Connecticut, in 1964.
Verborg’s problem was typical for a paper conservator—removing degrading pressure-sensitive tape that someone had once used to hinge the object. The Harvard Art Museum has more than one copy of the work. One print had an office-type pressure-sensitive tape, and the other had a Filmoplast-like tape. Both supports showed a small amount of planar distortion. There were already dark stains around the pressure-sensitive tape areas, causing concern that the adhesive would continue to sink into the media. The problem was complicated by the adhesive’s being directly adhered to the ink of the object, and by the plastic support, which would probably react poorly to heat application.
Verborg viewed other copies of the print in other institutions, and had access to the records of the print shop where they were made, as well as to recorded interviews with the artist and the opportunity to get information from Lichtenstein’s wife and a printer’s assistant from the print shop.
One interesting question arising from Lichtenstein’s use of a transparent support is which side is the recto? Lichtenstein, when asked many years later, said that the print should be ink-side up, which is reasonable for a print. However, both the printer’s assistant and Mrs. Lichtenstein remember that the ink should be on the verso, so that you have the glossy effect as well as the extra depth from looking through the support to the image. This is further supported by having the drinking glass in the composition on the right, where a right-handed person would normally place it.
Verborg had the materials tested with GCMS, FTIR, Raman Spectrometry, and LDI-MS (Laser Desorption Ionization Mass Spectrometry). The original printer’s invoice called the plastic “acetate,” but this seems to be a generic term for any clear sheet plastic. Analysis revealed it to be polystyrene, which is no longer available in clear sheets like this, and today we are more familiar with it in products like Styrofoam. The inks used a polystyrene binder as well, with PB 15 (phthalocyanine blue) as the colorant in the blue ink, and chrome red and some barium sulfate in the red ink. The paper-type tape was made of cellulosic material and the clear tape used PVA for both carrier and adhesive.
No one seems to sell clear polystyrene sheets anymore, so Verborg had to make do with other plastics for her mock-ups. As expected, heat caused the sheets to warp, making a heat treatment unwise. After removing the carrier, Verborg was left with sticky adhesive. Finding the right solvent for aged PVA adhesive that wouldn’t affect polystyrene would be difficult, as demonstrated by evidence of previous solvent tests on the ink layer, so she had to get creative, especially without the ability to make exact mock-ups. She finally tried sprinkling cellulose powder on the adhesive and then using a silicon color shaper to move the cellulose powder around, allowing her to remove the adhesive in small cellulose-powder/adhesive balls, leaving a clean surface.
This research has not only provided better insight into the working process of Roy Lichtenstein and his transition into experimenting with unusual print supports (one of the great advantages of screen printing) but also addresses other more universal problems such as the artist’s memory versus the artist’s probable intention, the unreliability of the labels people give to the materials they use, and how to remove sticky adhesive residue from a delicate surface.
Category: Specialty Sessions
Posts on talks that were presented as part of the specialty sessions at AIC’s Annual Meeting
41st Annual Meeting – Book and Paper Session, Thursday May 30, “Splintered: The History, Structure, and Conservation of American Scaleboard Bindings” by Renée Wolcott
After long, long neglect, the humble American scaleboard binding has seen a surge of interest in the last few years. Two articles feature scaleboard bindings in the recently published compilation Suave Mechanicals, Volume 1, edited by Julia Miller (Suave Mechanicals: Essays on the History of Bookbinding, volume 1. ed. Julia Miller. Ann Arbor: The Legacy Press, 2013. http://www.legacy-press.com). Miller herself presents the results of her survey of 858 scaleboard bindings in North American collections. John Townsend reports on a study of six copies of the same 1715 prayer book in scaleboard bindings.
Wolcott’s investigation neatly dovetails with and enriches those studies. Like Miller, and following methodology made popular by Nickolas Pickwoad, the basis of her work is a minute examination and recording of material and structural details. She examined 85 scaleboard bindings in the Library Company of Philadelphia, the Historical Society of Pennsylvania, and the Winterthur library.
Scaleboard is a thin (as little at one millimeter thick) planed wood used as the boards on popular American colonial publications from around the mid seventeenth to the early nineteenth centuries. These bindings, says Wolcott, are the product of a four hundred years of streamlining, simplifying, and cost reduction in bookbinding. Although the roots of this binding tradition can be traced to the European origins of the Colonists, the scaleboard binding is singularly American.
The texts so bound are usually popular subjects: sermons, religious tracts, pamphlets, hymns or songbooks, and especially in the later end of their popularity, primers and other basic textbooks. The audience for these books are churchgoers, parents, schoolchildren—these were the books, Wolcott explained, for the 99 per cent. These bindings have not been collected or treasured; the fact that they exist in library collections is because someone selected the text as worth keeping.
In addition to the eponymous scaleboard, the bindings are characterized by cheap sewing—typically stabbed with tawed, leather, or cloth thongs, or sewn on sunk cords—with very little fit and finish. The slips from the thongs attach to the boards by the simple expedient of pasting them down on the outside (under the leather) or the inside of the boards (under the pastedown—if there is one). The scaleboard binding is to the binding tradition, Wolcott asserts, what the Yugo is to the history of the automobile: basic, affordable, stripped down function—although not particularly durable function.
When looking for scaleboard bindings, first think small. Rarely are these bindings larger than octavo size. Gary Frost, commenting after Wolcott’s talk, suspects the size limit is related to the limitations of the tools used to make the boards—but the manufacture and production of scaleboard is a topic for further investigation. (Frost also mentioned observing scaleboards cut with hand shears, not with boardsheers or similar machines or jigs.) Scaleboard bindings are highly prone to damage—and that can make them easy to identify. Often the wood is visible through worn cover material. These books tend to be lighter weight than books made with pasteboard or fiberboard, and a gentle tap gives a hollow wood tone instead of a dull thud.
Most of the early imprints in scaleboard bindings before 1760 are from Boston. Over time the place of publication spreads out along the Eastern seaboard as far as Vermont in the north and Pennsylvania in the south. At least one binding Wolcott reviewed gives the place of publication simply as “New England.”
Of the 85 bindings Wolcott recorded, 55% were stabbed with two strips of tawed skin or leather; 44% were sewn through the fold, on recessed cords. She showed some fascinating images of books that had been notched for sewing on recessed cords, whether they eventually were sewn that way or not. Some books were notched but the leaf attachment was stabbed thongs, others were sewn on sunk cords using some but not all the notches. Yet another had evidence of temporary side stitching—and the notches. The evidence suggests that the text blocks were printed, folded, and sold pre-notched to others who might or might not use the notching for their binding. A minority, 13 bindings, were sewn on raised cords.
Endsheets for these bindings tend to the minimalist. Some books have none. Some, usually earlier books, use printer’s waste to form a simple pastedown that may be just a flange of a couple inches or may extend across the width of the board. Later books were more likely to have blank paper for endsheets.
The boards on all but five examples in Wolcott’s study have the grain running horizontally. Where the grain is vertical, it has a strong tendency to split with use. Wolcott looked carefully at the wood, where it was exposed, for evidence of where on the tree truck it was cut from. Most of the boards—71 bindings—were from logs that were split and radially cut. Others were cut tangential to the wood grain; boards cut this way tend to warp. (Trust me—what you really need here are to see Wolcott’s diagrams; look for them in the BPG Annual postprint.) The variation suggests a trade and working techniques that were not standardized.
There has been some speculation about the types of wood used for scaleboard and assumptions that the usual suspects—oak, beech, and the like—were used. Wolcott partnered with a botanist at Winterthur, Henry Alden, who analyzed the wood on some of the examples she identified. They were surprised to find nine examples of ash boards. Ash is a hardwood that we currently associate with baseball bats; in colonial times it would be used for furniture and such like, but it is not normally associated with bookbinding.
The earlier bindings, up to around 1790, tend to be covered in full leather. Later bindings typically have a quarter-leather spine and paper sides. Wolcott showed several typical examples and variations. The leather is often thick and crude, with knife gouges on the flesh side that have not been smoothed out and turn-ins that are rough and uneven. Decoration, if there is any, is usually limited to some simple blind-tooled single or double fillet lines. One Germantown binding with greater pretentions to its medieval wooden-board predecessors had straps and clasps on the fore edge.
After 1790 the books examined are quarter-bound leather. Many have sides of blue paper. A few have decorated (stencil, marbled, or Dutch-gilt) paper; one has paper printed with the title page. Wolcott showed an example of a full-paper binding with a quarter-leather spine evident under the paper. Another example was covered over in coarse canvas. Music books, printed landscape, usually had a thick leather over wrapper, probably added by the owner for extra protection.
The combination of inherent weakness of structure and popular, frequently used texts means that repairs abound on these bindings. Often the thongs attaching the text block breaks. Wolcott showed examples of repairs involving straight pins, whip stitching of leaves or sections, and oversewing that encompassed both text and cover. The boards are highly prone to split and break. The might be repaired with thread, with cartridge paper glued down, even with strawboard glued over a stitched mend.
Wolcott concluded her presentation with some examples of conservation treatment. One was a full treatment of a 1787 German text she performed at the Center for the Conservation of Art and Historic Artifacts. She disbound the text, repaired the split board with a 25% gelatin solution, resewed, lined, and fitted the text back into the binding.
Generally, however, Wolcott does not advocate such invasive treatment of these bindings. Repairs, if performed at all, should be minimal. She showed an example treated by Stephanie Wolff at Dartmouth, where a ramie band was threaded through the book to replace a missing thong.
Scaleboard bindings are sufficiently rare that Wolcott recommends for most simply improved housing that is sturdy enough to support the fragile boards. She showed examples of tuxedo boxes build out with extra sheets of corrugated board to provide rigidity to the structure and to give the small book some presence on the shelf. An alternative structures adheres the tuxedo box into a hard-shell binder that can defend itself on the shelf.
In the question period Gary Frost speculated that the boards were made as veneer (cut with a veneer knife) instead of sawn wood, but also doubted that the early colonials would have had easy access to veneer knives. What tools would have been used? Wolcott agreed that there is much still to be researched and explored on these bindings.
AIC’s 40th Annual Meeting – Photographic Materials Session, May 11, “The Photograph Information Record” by Erin Murphy and Nora Kennedy
At last month’s AIC meeting, I had the pleasure of attending several of the PMG sessions, including this one on the Photograph Information Record, or “PIR” for short. The form was introduced in 2009 following several years of collaboration between the Photographic Materials Research Group, photograph conservators, and colleagues in conservation science, collections management, and curatorial. The goal was to create an international standard for an artist’s questionnaire, to collect essential information to aid in preservation efforts. The result was a concise, two-page form. A completed PIR covers the history and context of creation, ownership, exhibition, conservation, and publication of a photograph, and provides information about the tools and processes of image creation, printing, and finishing. It asks artists to discuss what aspects of the work they consider integral, and gives them an opportunity to provide a statement about the creation and preservation of the work.
In this session Erin Murphy, photograph conservator at the New York Public Library, reviewed the history of the PIR and discussed its present stage of development. Many institutions around the world have formally adopted the PIR, and now plans are underway to collect feedback from users in order to develop the next generation – a new and improved form.
French, Spanish, and Japanese versions are available, with more translations in the works. For some committees working on translations, it poses a real challenge to agree on terminology or create terms in the language that didn’t exist before. Some mentioned that those discussions may be suitable for the wiki, and for the glossary project.
Future goals include expanding the visibility and availability of the PIR on the web. Right now, the form is available in several languages as a free download on the AIC website at www.conservation-us.org/PIR. ICOM-CC-PM members can access it on the ICOM-CC website. The form can also be found on a few other sites, such as a gallery or library here and there. A secondary PR campaign will also help raise awareness and encourage more institutions, galleries, and photographers themselves to adopt this valuable tool. Some attendees suggested potential audiences, including photography curators, and the registrars’ groups of AAM and ICOM.
Another goal is to see if improvements can be made to the PDF format. Form fields in the PDF make it easy to complete the form, but the information is not easy to import into museum databases. The PIR’s creators would also like to see access to the PIR expand within institutions to reach more departments and researchers.
It’ll be exciting to see the new directions that the PIR form takes in the coming months.
AIC’s 40th Annual Meeting-May 11, 2012 Joint Session: Book and Paper Group/Research and Technical Studies, with the Archives Conservation Discussion Group and the Library Collections Conservation Discussion Group “Mass De-Acidification Today”
The session was a series of short presentations by the panelists followed by a question and answer session that was open to the floor as well as pre-submitted questions from the AIC membership.
The panelists were: James Burd, President and CEO of Preservation Technologies, LP; Michael Ramin, Project Manager Research/Analytics, Nitrochemie; Dick Smith, owner Wei T’o Associates; Fenella France, Chief, Preservation of Research and Testing Division, Library of Congress; Nora Lockshin, Smithsonian Institution Archive on behalf of Anna Friedman, Conservator, National Archives and Records Administration.
The first presentation by James Burd “Bookkeeper Deacidification: The Chemistry Behind the Process” began with a review of Preservation Technologies’ twenty years in business, including an overview of their products and services as well as the scope of their operations. Mr. Burd spent the most time describing the Bookkeeper process, that it is a non-toxic, non-flammable, non-VOC, odorless process that does not use solvents or produce effluents. The alkaline agent is magnesium oxide (MgO) and in the mass-process it is delivered in an inert suspension liquid in which the books are immersed, relying on an electrostatic attraction to cellulose to deposit the MgO in the paper. Mr. Burd referenced recent research at the Canadian Conservation Institute and assorted technical studies at the Library of Congress in support of the effectiveness of the Bookkeeper process and reminded the audience that whatever the challenges presented by brittle collections, the greatest risk is doing nothing.
Michael Ramin followed with his talk “Durability, Quality Control, and Ink Corrosion Treatment with the Papersave Swiss Mass De-Acidification Process”. Papersave is a solvent based process using hexamethylene disiloxane (HMDO) as the solvent and magnesium as the alkaline agent. For treatment, the books are placed in metal baskets, which are then placed in a chamber for pre-drying, treatment, post drying and re-conditioning. Papers, books and drawings can be treated by this process. The items are treated in a vacuum chamber which ensures saturation by the treatment solution followed by the reconditioning process which allows moisture back into the chamber and the moisture in the air activates the deposited alkaline reserve. The company performs regular quality control in line with the German Institute for Standardization (DIN) and has retained 12 years’ worth of data including surface pH and XRF measurements to determine distribution of alkaline reserve. Papersave also has sample sets for real time ageing at five and ten year intervals. According to Mr. Ramin, the Papersave process is alos safe for paper that has iron gall ink corrosion since “through the treatment the acid is neutralized without removal or migration of the ions, on the contrary some of the iron is bound and neutralized.”
Dick Smith’s talk “Wei T’o Paperguard: Comprehensively De-acidifying, Stabilizing and Strengthening Paper” was third in the line-up although all the presenters acknowledged Mr. Smith as a foundation researcher and advocate for the mass de-acidification of paper. The original Wei T’o product was one of the first on the market for the treatment of acidic paper and Mr. Smith spent a portion of his talk describing how he became interested in the science of paper de-acidification, explaining that even though a piece of paper is thin, penetrating the surface with an even distribution of an alkaline agent is not an easy task to accomplish, especially 30-40 years ago when the technology was not very advanced. Mr. Smith then went on to profile a new Wei T’o product, still in the development phase, called Paperguard which not only de-acidifies, but also protects paper from fungal growth and pests. It is a zinc-based process that is environmentally sustainable since the by-products of the process are recoverable.
The fourth presentation was by Fenella France “Taking the Measure: Treatment and Testing in Mass Deacidification” and started with a review of the Library of Congress’ research into the mass de-acidification process which began in the 1970’s and expanded in the 1990’s. While the Library of Congress has vast historical collections, they are also still taking in acidic collections from all over the world and their current mass de-acidification treats more late 20th and early 21st century books from India, Spain, USA, etc. than 19th century material. The initial goal for the Library’s research was to establish a process that would deposit an alkaline reserve that tripled the longevity of an item, Bookkeeper was selected and a treatment facility was installed on-site at the Madison building. Testing and quality control is ongoing, but Ms. France sees a real need for the library research community to do more independent testing and not rely on vendor sources since there is too much variation in test methods to allow for meaningful comparison of data. A single measure that could be applied across the different mass de-acidification processes would enhance the assessment process and allow for agreement on the definition of progress.
The final presentation was Nora Lockshin on behalf of Anna Friedman “Evaluating De-Acidification After 20 Years of Natural Aging”. Ms. Friedman’s research focused on a treatment group from a 1989-1991 project at the Smithsonian Institution Archives where over 500 architectural drawings out of a record group of over 2,000 were sent out for de-acidification with Wei T’o Soft Spray or an aqueous bath with Magnesium Bicarbonate. Ms. Friedman used surface pH testing and colorimetric measurements at 5 points across the front of a drawing to evaluate the long term effectiveness of the de-acidification treatments. The colorimetric evaluation did not show any trends, but the surface pH showed that the application of Wei T’o was very uneven across the surface of the document. This would make sense given the application process of Soft Spray. However, comparison with a control group showed that documents that had been treated for mass de-acidification did have a higher pH after 20 years of natural aging.
The open discussion that followed began with a submitted question
SubQ: Is spraying of individual items as effective?
A: Papersave and Paperguard cannot be applied singly- mass only
Q: (Emily Rainwater) As a user of post-Bookkeeper treated items, she finds a lot of residue from handling the books, e.g. turning pages.
A: (Burd)- The particulates should go away as the treated book ages. (France)- Early in the development of the Bookkeeper process the particles were fairly large; they’re smaller now, so the white powder problem should go away.
Q: (Eric Hansen)- Italian conservators and others have complained that Bookkeeper changes the feel of the paper. Will Bookkeper address this question in a direct way so that this issue can be settled?
A: (Burd)- People really shouldn’t be able to tell, he has spray with him and offered to let people spray samples of paper and feel for themselves. The particle size is small and the quality control protocol of mass de-acidification is rigorous. (Smith)- Is particle size really the issue? Are we measuring what we think we’re measuring in terms of quality control? The TAPPI tests that we generally use are a standard, but are not precise to our need.
Q: (John Batty)- What does Mr. Burd mean by “pure” alkaline reserve?
A: (Burd)The magnesium that Bookkeeper uses is of high purity, but also there is no residue of other treatment fluids after the process is completed since the Bookkeeper process is full recovery.
Q: (John Batty)- To Mr. Smith: are you planning to treat artist’s materials to a specific pH?
A:(Smith) Not just to a specific pH, but also using zinc to ensure fungal and pest prevention.
Q: (Johanna P) To M. Burd, how is the benefit to ink measured, given that iron gal ink is supposed to stay acidic? Also, what about the color change or yellowing of treated items?
A: (Burd) If you have an ink you want to stay acidic, don’t treat it with a de-acidification process. If you want to stabilize iron gall ink and protect the substrate as well, then the Bookkeper process can be directed toward strengthening of paper.
A: (Ramin)- Non aqueous is better treatment since the paper is not as stressed.
A: (Smith): Commenting on paper yellowing after treatment by Wei T’o; he took yellowing as a sign of effectiveness since it demonstrated penetration of spray (this was in the early days) but don’t give up on de-acidification, work on delivery of the alkaline reserve.
A: (Burd)- Commenting on yellowing- Since the Bookkeeper process doesn’t use a solvent, there shouldn’t be any yellowing. Some researchers have spotted yellowing due to aging of magnesium, but Burd thinks the books would probably have yellowed anyway, so the magnesium application just changes the characteristics of the yellowing. Burd went on to comment that yellowing is only present in artificially aged paper samples, and that 20 years is not long enough for real time aging to be conclusive.
A: (Ramin) Papersave tests show some yellowing in ground wood and to comment on mold remediation, the Papersave drying process kills mold, which is a side benefit. Once treated, collections tend to have better storage conditions, so mold is less likely to grow again
A: (Smith)- Zinc has potential for mold and pest prevention in addition to mass de-acidification.
A: (Burd)- Alkalization does help with mold prevention
Q: (Ursula ?): Could there be more natural aging studies? To Ms. France, given ten years of using Bookkeeper, are you doing any studies? To Ms. Lockshin: were the treated papers stored differently?
A: (France)- Yes, the Library of Congress is initiating a long term study.
A: (Lockshin) all treated drawings were encapsulated and then opened for analysis but were otherwise stored together.
Q: (Cathleen Baker): the audience knows a lot about the complexity of paper, but the ads and trade lit is a little unsophisticated and implies that mass treatment should be readily applied, whereas selection is a more complex process. What about the effect of mass de-acidification on lignin?
A: (Burd)- This has been reported in literature, but if you attack lignin you will make paper weaker, to prevent this effect, don’t select items that are brittle where the lignin or cellulose is already weak, they can’t be rebuilt by mass de-acidification.
A: (Lockshin) Commented that the Smithsonian receives many reference calls, people have seen an ad for a product and want information on its effectiveness.
Q: (Renate Mesmer) The Folger Library has just started a Bookkeeper project and wanted to comment that handling of books for the Bookkeeper process is extreme, given the fanning out and agitation. They have also found very high amounts of white deposits, and given these high amounts of surface deposits, is anything going to the core of the paper?
A: (Burd)- Since we don’t use solvents we have to fan the books so that the alkaline particles can make their way into the paper. If a book is too delicate for the mass process, then use the single item process. Distressed to hear that there are a lot of white deposits. Porosity of the paper is the dependent factor on penetration, but acids migrate toward the alkaline particles so this shouldn’t ultimately be a problem.
AIC’s 40th Annual Meeting – Paintings Session, May 9, “Frederick Hammersley: An Artist’s Documentation of His Painting Practice” by Alan Phenix
Pacific Standard Time is not just a time zone. It is also the title of a Getty-funded initiative, jointly launched by the Getty Foundation and Getty Research Institute, that enabled more than sixty cultural institutions across Southern California to tell the story of the art scene in Los Angeles, California. The initiative focuses on archives, research, exhibitions, publications, and other programs to record the region’s artistic history. A substantial part of the project is dedicated to Los Angeles art from post-World War II through the 1970s. In 2011/2012 The Getty Center held an exhibition entitled Crosscurrents in L.A. Painting and Sculpture, 1950-1970. One of the artists in the show was the painter Frederick Hammersley, who died in 2009. After Hammersley’s death a artist-endowed Foundation was established to preserve and maintain his artistic legacy. Getty researchers first encountered the extensive archive of materials held by the Hammersley Foundation during preparations for the Crosscurrents show. Alan Phenix presented to the Paintings Specialty Group some introductory observations on the wealth of that information.
Frederick Hammersley was a leading abstract painter in Southern California in the postwar period. He first gained widespread notoriety in 1956 when he was included with artists Karl Benjamin, Lorser Feitelson, and John McLaughlin in an exhibition entitled Four Abstract Classicists. The show led to the coining of the painting movement known as “West Coast Hard-Edge”. Hammersley was born in 1919 and studied art in the 1940s at the Chouinard and Jepson Art Institutes in Los Angeles. He stayed on at the Jepson Institute in a teaching capacity after he finished his studies. He also held subsequent teaching positions at Pomona College (1953-62), Pasadena Art Museum (1956-61), and Chouinard (1964-68). In 1968 he took a teaching position at the University of New Mexico in Albuquerque, which he kept until 1971 when he stopped teaching to concentrate on his painting. He continued to work at his home studio until six months before his death and his space remained essentially untouched after his death, serving as final documentation of his life and work. Hammersley had also fastidiously documented his artistic process in series of notebooks for a period of more than 50 years with few interruptions. Among the most notable of these were four “Painting Books” that consist of cumulative and descriptive chronological lists of works completed. The project being undertaken by the Getty Conservation Institute aims to examine and interpret that archive of materials for what it may reveal about Hammersley’s process, materials and techniques, and what it might mean for the preservation and conservation of his work.
Hammersley’s painting had a strong psychological element, which is illustrated in the evolution of his work. From 1954 to 1959 he worked on a series he called “Hunch” paintings, which developed without preparation as the artist relied on “hunches” coming from reflection and intuition to guide his work. In 1963 until 1965 he worked on series defined as “Organics” and “Cut Ups” that expanded upon his intuitive painting with more organic processes. In several periods throughout his career he also worked on more hard-edged geometric paintings. An early instance of his documentation and creative evolution was found in a set of notes on labels on the back of a 1956 “Hunch” painting entitled In Front Of, in which he recorded dates for the addition of specific shapes in the composition.
The artist began keeping his “Painting Books” in 1959, wherein he kept lists of his work, information about his process, when and to whom each work was sold, and other related information. The details of his records continued to increase and by 1966 he’d expanded his notes to include additional items, such as information on specific paints.
It was interesting to hear that Hammersley’s documentation was not limited to formal records and itemized lists; his notebooks were also works of art in their own way. Some of his books contained visual composition ideas in thumbnail sketches. When he liked a composition he would execute it in a slightly larger (ca. 3″ x 3″) format. Eventually he began including sequential breakdowns of the development of particular artworks. On occasion he would revisit past artworks and those changes were also documented in his notebooks. The artistic process was not limited to the works themselves. Hammersley kept a “Titles” folder that contained lists of words written by free association. When he came across words he liked he would underline them and then retrofit them to create titles for particular works.
This presentation just scratched the surface of the available information in Hammersley’s personal documentation. The goal of the Getty Conservation Institute’s work is to make the mass of information of Hammersley’s archive available to a wider audience, including conservators who may have cause to work on his paintings in the future. A searchable database is envisaged once the material is transcribed, collated, and interpreted.
This year’s annual meeting was focused on connecting to conservation through outreach and advocacy. A searchable database of artists’ materials and techniques certainly has potential to assist with that effort.
AIC’s 40th Annual Meeting – Paintings Session, May 9, “Relating Artist Technique and Materials to Condition in Richard Diebenkorn’s ‘Ocean Park’ Series” by Ana Alba
When Ana Alba was working at the Hirshhorn Museum she undertook a research project on four paintings from Richard Diebenkorn’s “Ocean Park” series. Her study compared the materials used in each of the paintings and assessed how that tied in to their current condition. She presented her findings at the 2010 annual meeting in Milwaukee, Wisconsin. Two of the paintings had severe cracking while the other two were in good condition; the paintings with the cracking had an acrylic preparatory layer. At this year’s annual meeting she presented research conducted at the National Gallery of Art that expanded upon her intial study.
Ana’s current research involved the examination of more than 45 paintings and samples for analysis were collected from approximately 15 paintings. All of the information gathered was compiled into an extensive chronological database. An additional list of travel histories with photographic references was completed. The results of this study showed changes in the artists materials both between paintings and within individual works.
Diebenkorn worked for weeks to years on some of his paintings. He painted consistently on unsized cotton duck but his choice of preparatory materials fluctuated over time. Between 1968 and 1973 he used white acrylic gesso and toned it with diluted acrylic. In some cases he added alkyd. From 1973 to 1978 he transitioned from white to clear preparatory layers, presumably in order to maintain the raw canvas color and achieve transparencies in his paint layers. Scientific analysis suggested the clear material was synthetic and consistent with Rhoplex AC-33. This was more or less confirmed by photographic evidence of showing large jugs labeled as Rhoplex located in the artist’s studio. By 1979 Diebenkorn had returned to using acrylic gesso almost exclusively.
Diebenkorn primarily painted with acrylics and alkyds. He added oils sparingly and extended his paints as far as possible. He also used charcoal, graphite, and colored pencil to define his images. Infrared reflectography of his paintings show numerous alterations in his compositions, which is unsurprising given his appreciation of layering and the amount of time he spent working on each piece. Once a painting was finished he applied matte fixative to the surface. In his early works he applied this in 6 or 8 consecutive layers that left a glassy, heavy surface. Eventually he shifted his process and masked out the painting to limit application to the charcoal areas.
The condition assessment of this larger group of paintings seem to support the findings of Ana’s initial study. Paintings executed between 1960 and 1973 vary and some show some cracking. The cracks follow drawn lines, compositional changes, and are greatest on the paintings with heavy layers. Paintings completed after 1973 and before 1980 have heavier, more pronounced cracking with broad and isolated areas of cupping. These paintings follow the same trend as the earlier works with the greatest cracking located in the layered areas. Diebenkorn’s paintings after 1980 are in much more pristine condition with less cracks. The trend of this condition timeline show that the paintings in the poorest condition are located in the middle of the Ocean Park series. This supports previous findings by showing that paintings with Rhoplex and acrylic exhibit the worst cracking, especially when they are painted thickly with numerous layers.
This study highlights concerns regarding some of Diebenkorn’s selection of materials. Alkyds are brittle so putting them over flexible preparatory films and unsized canvas makes them susceptible to cracking from impacts and physical movement of the substrate. Fortunately, they do not seem prone to delamination so the cracking does not lead to significant paint loss. In addition, when Diebenkorn diluted his materials he reduced their strength. That left them with a greater chance of deformation in response to physical and environmental factors.
Ana pointed out that there are some limiting and extenuating factors to consider in this research. The are as follows:
- No samples were taken from privately owned paintings.
- His assistants did not see him working so they could not provide information about his process
- Diebenkorn did not keep detailed records of his work or do preparatory drawings.
- The study compares paintings in good and poor condition only.
- The artist destroyed some works, painted over others, and skipped #5 when creating the series.
- One large painting from Brooklyn was an outlier in the study; it was completed prior to 1973 but it shows significant cracking across large ares of the surface.
During the question and answer session following the presentation it was also noted that areas with Rhoplex on raw canvas showed discoloration.
I have a personal appreciation for Diebenkorn’s work and have enjoyed following the progression of Ana’s research project. By coincidence, I had the opportunity to realize that interest in person this week when the exhibition, Richard Diebenkorn: The Ocean Park Series, was deinstalled at the Orange County Museum of Art in California. I conducted outgoing condition assessments of some of the paintings and was able to see exactly what Ana had discussed in her presentation. The exhibition will open at its final destination, the Corcoran Gallery of Art, on June 30th. I encourage all of you to check out the show if possible to see the subjects of Ana’s research side by side for the first time on such a large scale.
AIC’s 40th Annual Meeting – Paintings Session, May 9, “Print or Painting? The Treatment of a Penschilderij by Willem van de Velde the Elder” by Kristin deGhetaldi
Penschilderijn*, also known as “penpaintings“, involve drawing an image in black ink on top of a substrate prepared with a white lead oil ground. The technique originated in seventeenth century Holland and was popularized by one of its most skilled practitioners, Willem van de Velde the Elder. The artist’s painting, Dutch Ships Near the Coast, became the first penschilderij in an American public collection when it was gifted to the National Gallery of Art in 1994. Treatment of the painting began in 2010, which gave conservators the rare opportunity to conduct an in-depth study of the materials and techniques utilized in its creation. Kristin deGhetaldi headed the treatment of the painting and presented the current study findings and treatment results to the Paintings Specialty Group.
Willem van de Velde the Elder built his career on pen paintings but his beginnings were much more humble. He was born in 1611 as the son of a skipper and spent most of his early years on ships, giving him a natural familiarity with navigation and the sea. He was also an excellent draughtsman and became skilled at sketching maritime scenes. As his skill improved he was sought for victory images and his clientele of wealthy patrons increased. He gained significant notoriety with his penpaintings as early as the end of the 1630s and it was said that his penschilderij were considered more popular and valuable than his other works.
Penpaintings were often done on panel or vellum primed with oil. Working atop these surfaces with pen and ink made it difficult to make corrections to the composition. Van de Velde was a perfectionist who was easily dissatisfied with the quality of his work. If he did not like a sketch he would go over the basic outline in wet ink and quickly press the image to another substrate and begin again. He also utilized both fine line drawing and washes to create his images, with washes becoming more prominent in his work by the 1650s. Washes provided the advantage of covering large areas quickly without the need for intricate underdrawings. This allowed the van de Velde workshop to generate larger penpaintings at a faster rate in order to meet teh demands of the market.
A visual analysis of Dutch Ships Near the Coast was conducted in comparison to van de Veldes other known works and some characteristics stood out. Although it is dated to the 1650s, the work is smaller than his other penpaintings and it lacks the expected fluid washes in favor of fine linear strokes. The penpainting does have an underdrawing, though it remains unclear whether it was sketched in silverpoint or graphite. In addition, the ground layer composed of calcium carbonate instead of the slightly darker ground that is common in his similar works. Finally, unique raised lines are present where the ink is applied and in other areas of the white ground.
Scientific analysis was conducted in an attempt to clarify some of these discrepancies. Cross-sectional microscopy revealed two layers of lead white, with the topmost layer containing particles that were more finely ground. The presence of only carbon black in the ink design confirmed that iron gall ink or bone black was not used by the artist. Analysis using GCMS was conducted in an attempt to identify the binding medium of the ink, though the tests were inconclusive.
Conservators decided to create a reconstruction of the penpainting to gain insight into the identity of the oil binder and find possible causes for the raised lines. Linseed oil was used in the reconstruction but it yellowed quickly, leading conservators to believe a slower drying oil was used in order to avoid the discoloration. Next conservators tested reed and quill pens dipped in gum based ink to determine how the ink was likely applied. Reed seemed like a good candidate but they produced broader and less precise lines than the sharp, fine lines created with quills. Goose quills were ideal but quills from raven and crow feathers were also acceptable. It was hypothesized that the sharp quills may have scratched the ground before it was totally dry and created the fine lines. However, that did not account for the raised nature of the lines or the fact that they existed in areas where ink was not applied. At that point conservators wondered if the lines could be the result of engraving techniques.
The Dutch artist Experiens Sillemans was a contemporary of van de Velde and also created penschilderijn. Sillemans was known to use printmaking practices such as engraving in the creation of his works. The technique involved pressing a freshly inked engraving on to a primed support. To create raised lines, however, van de Velde would have had to press his inked copper plate into the soft preparatory ground of the support. Given the art historical evidence, it still seems unlikely that van de Velde used this practice as no two of his penschilderij are alike. In addition, there are no prints in his oeuvre to suggest he was a practiced engraver.
Ultimately the technical study of Dutch Ships Near the Coast left more questions than answers and conservators are hopeful that future study will lead to greater understanding. At that point it was time to address the treatment of the piece.
Examination of the painting revealed fills and overpaint, discoloration, flaking, and crumbling around the fills. The abraded surface was almost ghost-like in some areas and the face of one man in the foreground was completely lost. The painting was stabilized using sturgeon glue. During removal of the varnish layers, Kristin did not have to worry about solubility issues.** Once the painting was given an isolation layer of MS2A varnish, losses were filled using a mixture of Aquazol 200 and Modostuc. To begin the inpainting process Kristin isolated the painting with MS2A and then used pigmented micropens under magnification to conduct a painstaking recreation of the abraded areas. The damaged background was reinforced with thin HB micro graphite sticks.
A question and answer session followed Kristin’s presentation and someone asked what additional theories she may have regarding the cause of the fine lines. Kristin said she has a few weak theories. One theory is that the penpainting was put in the sun to bleach and dry, during which time the black ink may have absorbed more heat and created the lines. Her second theory was that a slower drying oil like walnut or poppy may have left the grounds soft and created uneven drying which could have led to the raised lines. She stressed that more study is necessary.
I thought this was a very interesting presentation and look forward to hearing about future developments in the study of Willem van de Velde’s penschilderij.
* A past study by David Freedberg, Aviva Burnstock, and Alan Phenix refer to these works as penschilderijen. Since I am not fluent in dutch, nor an expert on penpainting, I deferred to the spelling used by Kristin deGhetaldi.
** The question of solubility was raised during the question and answer session, to which Kristin replied she detected absolutely no solubility issues in the materials of the penpainting, especially since the painting had already been subjected to harsh overcleaning in the past.
AIC’s 40th Annual Meeting – Paintings Session, May 9, “Treatment of Izhar Patkin’s ‘The Black Paintings’–Collaboration and Compromise” by Jennifer Hickey
Israeli-American artist Izhar Patkin’s work combines traditional painting and sculpture with nontraditional techniques. In 1986 he completed his work, The Black Paintings, a series of twenty-two pleated neoprene panels painted with images based on Jean Genet’s play, “The Blacks: A clown show.” The 14′ long panels hang side by side to create a 28′ x 22′ installation. Recently, the sculpture and painting conservation departments at the Museum of Modern Art in New York collaborated to address the treatment of this work. Jennifer Hickey presented the challenges, philosophy, and compromises of the project to the Paintings Specialty Group.
When conservators took on The Black Paintings they were met with a host of interesting challenges. The first set of issues had to do with the materials. Neoprene is a stable synthetic rubber that maintains its flexibility over time and wide temperature variations. It is not an ideal substrate for painting because of its flexibility and the size and weight of each panel exacerbated that problem. The artist was aware of those issues and used spray paint and vinyl paint under the assumption that the spray paint would crack while the vinyl paint would remain flexible. Unfortunately, the expected interactions of the materials proved false as the entire painted surface cracked and flaked with the stretch of the neoprene. The cracking and losses were compounded by the handling required to deinstall and reinstall the panels each time they were exhibited.
The physical incompatibility of the neoprene and paint media was not the only problem. Neoprene is often coated with a talcum-based release agent to keep it from being sticky. The application of the talc leaves a hazy gray surface that the artist liked so he painted on it without removing the coating or preparing the surface with another material. Therefore, the release agent that kept the neoprene from being sticky also acted as a release agent for the paint media.
Conservators were also faced with challenges that went beyond the materials. Izhar Patkin is a living, working artist so conservators were able to consult him during the assessment and planning stages of the project. This may sound like a blessing if we consider all the times we’ve wished for input on a complicated project from its creator. However, it can be a double-edged sword and that was the case with The Black Paintings.
As previously mentioned, Patkin was aware that the painted surfaces would deteriorate and enjoyed the nonstatic idea it presented. He chose his materials to encourage that deterioration and scratched into the paint to initiate the process. He also appreciated how the heat of the installation space intensified the smell of the neoprene. Perhaps it was serendipitous that such heat adds to the risk of instability in paint films. Conversations with the artist allowed conservators to understand where he’d intended damage and deterioration, which guided their treatment decisions. At the same time they ran into complications during their discussions. For example, the artist and conservators used the word “craquelure” to describe different phenomena and the conservators had to contend with impractical suggestions from the artist.
In the end the treatment of The Black Paintings was limited to triage with the understanding that maintenance treatment will be required each time the panels are unrolled. Conservators designed a cleaning system that accounted for the sensitivities of the solvent based paints and avoided heat, which could have compromised the rubber. The panels were hung and then gradually lowered to a table for access, at which point they were cautiously dry cleaned and a very time consuming consolidation was undertaken using an acrylic emulsion adhesive. An old interleaving was replaced with finely woven undyed cotton and permanent cleats were secured to the tops of each panel. At that point the panels were rerolled and stored. A manual was prepared to instruct all individuals on the proper handling during all future installations and deinstallations.
This was a very complicated project that illustrated many of the issues that arise when dealing with modern and contemporary artworks and the involvement of a living artist. A question and answer session following the presentation continued to highlight the gray areas surrounding these kinds of treatments.
One conservator asked Ms. Hickey why they chose to roll the panels with the paint side facing inward rather than out because of the added risk it posed to the already unstable paint. Ms. Hickey explained that the size and weight of the panels necessitated this compromise because they were too large and heavy to flip over once the panel was unrolled. Rolling them in this way may risk the paint but significantly reduced the level of handling and resulting unavoidable losses.
A second question posed to Ms. Hickey was whether or not they thought of alternatives to the permanent cleats because rolling the paintings with the cleats creates a risk. When Ms. Hickey explained that the budget of the project would not allow other preferable but more expensive alternatives she was asked if they considered the fact that additional costs at present could maintain value in the piece and curtail future treatment costs. Ms. Hickey addressed this question with great poise by reminding us all that conservators do not always have the final say when it comes to the cost of a treatment and sometimes we must find the best compromise available within our limitations.
This was an excellent presentation and I hope it will lead to continued discussions regarding the issues that arise in these kinds of complicated projects.
AIC’s 40th Annual Meeting – Paintings Session, May 9, “Challenges and Choices in Conserving an Early Abstract Expressionist Painting by Clyfford Still” by Barbara Ramsay
American painter Clyfford Still (1904-1980) was a leading Abstract Expressionist artist. In November of 2011 the new Clyfford Still Museum opened in Denver, Colorado. For more than seven years prior to the opening conservators in the ARTEX Conservation Laboratory worked to prepare Still’s paintings for travel and exhibition. One of those paintings was the oil on canvas, 1943 (PH-286). Barbara Ramsay carried out the treatment of the painting and kept coming back to the question, “Should we hold the artist accountable for the materials and techniques that he has used, or should we attempt to reintroduce aspects of his original intent as we perceive them?” As one might expect, the answer is often complicated and open to interpretation.
1943 (PH-286) is a key early painting in Still’s oeuvre that serves as an excellent documentation of his artistic process. The painting represents his transition from abstracted figurative work to the complete abstraction for which he is known. It is understood that Still considered the painting to be an important work and he exhibited it more often than most of his other works. The painting also important because it has the inscription “White and Black” on the verso, which may be an early title because he did not completely abandon titling his work until some time in the 1940s.
The stretched painting was executed on unsized cotton duck canvas with a white ground. The canvas showed signs of being unstretched and restretched more than once. It was slightly stained but otherwise it was generally stable. Examination of the paint layers revealed mingling of matte and glossy areas and a discolored surface coating. The areas of highest gloss appeared bluish white under ultraviolet irradiation but whether there was a local or overall surface coating remained unclear. There were also areas of marked drying cracks in the black paint layers but all of the cracks appeared to be stable.
After minor consolidation, the structure of the painting was stable so the focus of treatment was on the aesthetic qualities. Barbara’s approach was to open up a dialogue between curators, the representatives of the Still estate, and conservators to discuss the interpretation of the condition and determine a course of action that prioritized minimal intervention. Unfortunately, such conversations are often complicated and this case was no exception. Some of the stakeholders felt the painting should be left as is. Others wanted the drying cracks to be inpainted. Still others wanted a complete aesthetic treatment to remove and replace the discolored varnish, saturate the matte areas, and inpaint the drying cracks. Barbara wanted to do more research before determining her ideal course of action. The critical questions: could it be done safely and should it be done at all?
To answer those questions Barbara focused on Still’s working process. GCI analysis suggested that he used titanium white ground, zinc white, carbon black, organic colorants, and some commercial tube colors on his paintings. Many of Still’s paints are known to be particularly sensitive to water and organic solvents. The variable gloss in the paint surface posed several other issues for consideration. The matte areas could have indicated an original difference in leanness in the paint. It was possible that Still applied an overall surface coating that soaked into areas of underbound paint over time and left an unexpected variable gloss. There was also a chance that Still applied the coating to specific areas of the painting. So, did Still apply a coating? Was it local or overall? Did he intend or like the uneven surface? Research turned up examples where Still did both localized and overall surface coating applications. It was documented that paint that appeared “too dry” was not his original intention. However, what did he mean by “too dry”? Was this an “overly matte” surface or did it describe a surface that had traces of efflorescence?
Additional study by the GCI identified a drying oil on the surface and it was determined that Still likely coated the painting with the oil in the 1970s. Examination under ultraviolet irradiation supported the theory that the oil coating was absorbed by leaner areas of paint, resulting in localized matte patches. Although the oil was applied by the artist there was no documentation to indicate what effect he was trying to achieve. Since the discolored coating was very disfiguring and misleading, it was decided that it should be removed. But could it be removed?
As expected, solvent sensitivities in the paint layers complicated the removal of the surface coating. As a result, it was determined that selective and partial cleaning was the most viable option. Using solvent compresses the coating was reduced in the whites, grays and colored areas, but was left untouched over the black paint. A varnish was not applied either to the cleaned areas or to the matte black paint passages.
The last step in the treatment was inpainting of the craquelure. Barbara preferred to leave the craquelure as evidence of the artist’s materials and working methods but finally agreed to inpaint the most distracting craquelure with a reversible medium. At that point the treated painting was ready for exhibition.
This was a complicated project full of the difficult questions that seem inherent in the treatment of modern and contemporary art. As a result, the conclusion of Barbara’s presentation was followed by a very interesting question and answer session. I was unable to keep a written record of the various dialogues that occurred but I can recall one question and answer that I thought was interesting and could lead to additional discussion: One conservator asked Barbara why she decided to inpaint the craquelure when Still had chosen to exhibit it for so many years in that condition. Barbara replied that she had considered this factor and believed it was a valid reason not to inpaint. She did not want to inpaint the craquelure but she feared the other alternative was that the painting would not go on exhibit. She felt it was necessary to compromise on inpainting the cracks to ensure that such an important painting would be included in the inaugural installation in the new museum. She noted also that Still had not intended that the drying craquelure would form. She felt the museum’s desire to show Still’s work to the public for the first time looking its very best was also a valid concern. What do you think?
AIC’s 40th Annual Meeting, Objects and Research and Technical Studies Joint Session, May 9, “The Qero Project: Conservation and Science Collaboration over Time,” by Emily Kaplan et al.
Emily Kaplan (Presenter), Objects Conservator, Smithsonian National Museum of the American Indian; email: kaplane@si.edu
Ellen Howe, Conservator, Sherman Fairchild Center for Objects Conservation, Metropolitan Museum of Art; email: ellen.howe@metmuseum.org
Ellen Pearlstein, Associate Professor, Conservation of Archaeological and Ethnographic Materials, UCLA; email: epearl@ucla.edu
Judith Levinson, Director of Conservation, Division of Anthropology, American Museum of Natural History; email: levinson@amnh.org
The qero research project is a seventeen-year-long collaboration among object conservators at four museums with qeros in their collections: the American Museum of Natural History (AMNH), the Brooklyn Museum, the Metropolitan Museum of Art (MMA), and the Smithsonian’s National Museum of the American Indian (SI, NMAI). Emily Kaplan (SI, NMAI) presented an update of the research to date on behalf of her co-investigators, Ellen Howe (MMA), Ellen Pearlstein (formerly Brooklyn Museum, now GCI-UCLA), and Judith Levinson (AMNH). The project is an in-depth technical study of materials and techniques of fabrication of a corpus of qeros, polychrome wood drinking vessels fabricated around the time of the Spanish conquest of Peru in 1532; the qeros in these four collections date from the Inca period (13th-15th c.), through the Colonial period (16th-19th c). Consequently, the qeros offer material culture insights produced over a span of centuries and reflect the influences of both indigenous cultures and Spanish colonizers. Principal goals of the project involved: understanding techniques of fabrication, the analytical identification of materials, and the correlation of the technical data with the stylistic data proposed by others (i.e. curators, art historians).
The qero project was an apt presentation for the joint OSG-RATS session. Kaplan articulately presented the cultural history of the vessels, as well as the technical research undertaken by numerous conservation scientists, principally at the Boston Museum of Fine Arts and at the Metropolitan Museum of Art. Indeed, both cultural and scientific research were presented in nearly equal measure, which underscored the efforts of the primary researchers to cover both aspects in depth. Efforts at replication of techniques of manufacture, cultural exchanges with colleagues and artisans in Peru, and the application of the full arsenal of analytical methods employed (including FTIR, GC-MS, PLM, XRD, and XRF) were discussed. Kaplan noted that YouTube videos exist showing contemporary Columbian artisans in Pasto working with the sheets of resin. The presentation was accompanied by quite beautifully photographed images of the vessels themselves, comprised of tropical woods with polychrome resinous inlays, which illustrate geometric (Inca) and figural (Colonial) design registers of increasing complexity.
Funding from the MMA and NMAI allowed Kaplan and Howe to travel to Peru to meet Andean artists and scholars; to collect raw materials; and to visit private and public collections. Eventually botanical samples of the plant elaeagia were correlated via FTIR and GC-MS to the mopa-mopa resin noted in early literature and the samples from qeros. Interestingly, the palette was identified as largely unchanged from the pre-Colonial period. Colorants identified include cinnabar red, orpiment yellow, cochineal red and pink, indigo blue, copper-based greens, carbon black, lead white and titanium white. A notable, recent reassessment is the meaning of the analytical identification of titanium white (cristobalite anatase in mineral form) on some vessels. Early in the project, the noted presence of titanium white—a pigment that found wide usage only in the 20th century—was thought to indicate areas of restoration. Further study focusing on the presence of elaeagia in the media, led the conservators to believe it to be a pre-Colonial pigment. A known Andean ore does exist.
Current research questions involve study of the ore source(s) of the cristobalite anatase and pigment comparisons to Colonial Andean paintings. Further, the research and data collection evolved with technological advances and the collaborators are now considering ways to aggregate and share the data on-line.
This research project can be seen as a model for other conservation projects involving multiple institutions. The sustained curiosity about these objects inspired a prolonged inter-museum collaborative effort , involving international allied professionals. I’ve followed the progress of the qero project over the years, attending presentations and watching the list of publications in the US and South America grow longer and longer, as new findings emerged. Near the beginning of the project (which started in 1995), while a graduate conservation student at New York University, I participated for two years as a research assistant on the project. The concerted efforts to study both historical techniques of fabrication and the scientific results of analytical testing represent for me why the qero project ideally embodies the captivating interdisciplinary aspects of the conservation profession.