42nd Annual Meeting – Research & Technical Studies, May 31, “Development and Testing of a Reference Standard for Documenting Ultraviolet Induced Visible Fluorescence” by Jennifer McGlinchey Sexton, Jiuan Jiuan Chen, and Paul Messier

Jennifer McGlinchey Sexton, Conservator of Photographs at Paul Messier, LLC, presented on the testing of reference cards and the development of new imaging protocols that are so desperately needed in our field for increased standardization and comparability of photographs taken of UV-induced visible fluorescence phenomena. The project started by private photograph conservator Paul Messier in 2006, under the servicemark name UV Innovations (SM), was taken over by Jiuan-Jiuan Chen, Buffalo State’s Assistant Professor of Conservation Imaging, Technical Examination, and Documentation at Buffalo State College. Sexton has directed development of the  Target-UV™ and UV-Grey™ products since 2012.
Many a visual examination is followed by technical imaging, including both Ultraviolet Fluorescence (UV-FL) and Visible-Induced Luminescence (VIL), and Sexton’s talk first reiterated why observing cultural material by using carefully selected wavelengths of light is important:  It is non-invasive, relatively inexpensive, accessible, and (largely) commercially available. As a surface technique, UV-induced fluorescence probes outside layers, coatings, optical brighteners, mold, tidelines, and organic-glaze pigments above bulk pictorial films. Although it is a technique we rely on for the large majority of condition assessments and technical studies, our documentation remains unstandardized, and essentially, unscientific. With so much to gain by standardizing our capture and color-balancing process, as well as by taking careful notes on the equipment used, the prospect of the Target-UV™ and UV-Grey™ UV-Vis fluorescence standards is certainly an exciting one.
UV-FL images are unique in that they contain diagnostic color information, hence the need for standardization, which would enable cross-comparison between colleagues and between before- and after-treatment documentation. The beta testing of the UV target which was been carried out for 2 years has attempted to account for the most significant variables in the production of UV-FL images. The talk evidenced the enormous amount of collaboration and communication needed to streamline the significant aspects of equipment choice, the optimization of acquisition, and the documentation of post-processing methods. The goal was to increase reproducibility and comparability. Sexton’s presentation showed that the beta testing of the product achieved demonstrable results in terms of uniformity of output.
Development of the UV target was begun in collaboration with (Golden) to produce stable fluorogenic pigments of known color values and known neutral-gray values (which were evidently produced by mixing the red, green, and blue fluorogenic pigments). Neutral gray was defined as a gray which was interpreted as neutral by many viewers and which performed similarly under many different conditions. Including such color swatches within a photograph–for the purposes of color-balancing and correcting any variation in the Red-Green-Blue channels for each pixel–is a very familiar principle in visible photography.
A second consideration made for the round-robin testing was that of intensity, which is a variable somewhat unique to UV-FL photography. The nature of the emissive source must be noted for purposes of calibration and exposure, especially as all light sources currently used in fluorescent photography lack stability over long periods. The output of a lamp with fluctuate over time, and this makes relative intensities of materials illuminated with some lamp types very difficult to determine. Even when this particular factor is taken into account, other variables, such as the distance of the lamp to the subject and the wattage of the lamp will effect intensity. It is also possible that multiple emitting sources could be present. These factors should be included in the metadata for the exposure.
To control for this intensity factor, beta testers were to divide their sources, distance-to-subject, and wattage parameters into three different intensity levels which were best matched to certain analyses: “Ultra” was beta-tested for analysis of optical brighteners and other products produced specifically to fluoresce. “High” was best for the analysis of natural and thicker fluorescence, perhaps of a paint film such as zinc white, of some feathers (see Ellen Pearlstein’s talk from this year Ultraviolet Induced Visible Fluorescence and Chemical Analysis as Tools for Examining Featherwork”), and uranium glass colorants; and “Low” was used to image thin applications of resins, varnish, and sizing films.
A third variable was that of camera sensitivity, which varies with manufacturer (proprietary internal filtration and software), camera type (either DSLR or digital back cameras), as well as with sensor type (CCD or CMOS, modified or unmodified). Different filters were tested (Kodak Wratten 2e pale yellow filter, PECA 918, and an internal blue-green IR (BG-38) filter). These types of internal filtration are typical on digital cameras to block out IR and some red light to bring the camera output closer to the typical photopic curve of the eye and more closely mimic human vision. The 2e filters UV radiation and a small amount of the blue light commonly emitted by UV lamps, while the Peca 918 is used for IR blocking.
The fourth variable tested was the source type. Those tested included low-pressure mercury, high-pressure mercury, arc and metal halide arc lamps. Although LEDs were used at some institutions, many of these have a peak emission at 398 nm, which is barely in the ultraviolet range. Greg Smith at the IMA analyzed Inova X5 UV LED, and found that it does contain UV but is more expensive. Other products show a large difference in emission peaks which often cannot be accommodated by a simple white-balancing operation. Therefore, testing limited the peak emission to the most common types, emitting between 360 and 370 nm.
The last variables that were analyzed were those of post-processing procedures and software and of user perception and needs. An problematic paradigm identified over the testing period was that of the image being readable or resolvable vis-à-vis a particular argument versus the image being strictly accurate and well-calibrated. A photograph may accurately render the intensity of the fluorescence but it may be so completely underexposed so as to be unreadable.
Testing showed that, despite these difficulties of calibration and subjective experience, that the workflow incorporating the UV Innovations standard, showed a marked increase in standardization. Round-robin testing was completed by eight institutions in the US and Europe in May 2013. Fluorescent object sets were shipped along with the UV standard and filters. Each test site collected two image sets, one named “a,” using the lab’s current UV documentation protocol with color balance and exposure set “by eye,” and the other named “b” using the UV innovations protocol. The increased control provided by the use of the standard was evidenced by the average delta E of L*a*b* data points as well as the average standard deviation of RBG data points for both a and b sets as each institution. By way of example, the ‘Low—a” set showed an improvement from a delta E of 18.8 to the ‘Low—b” with a delta E of 4.9. The average standard deviation in-between these two sets showed an improvement from 32.8 to 6.2!
The presentation went into depth about how this data was collected, how variables were controlled for, and how the data was analyzed, and it showed convincingly that despite the high variability of current work flows,  the UV Innovations UV-Grey card and Target-UV standards in conjunction with standardization of UV source and filtration can markedly improve the image variability of UV-FL photography.
One variable in “extra-spectral” imaging that was not addressed in this talk were the spatial inhomogeneities of the light source, or the gradient that results from the use of an inconsistent light source. This could be especially problematic if using UV-FL photography for condition imaging, and “flat-fielding” should be considered as a possible augmentation to the ideal image-acquisition protocol.
There is still further research to be done before this product hits the market. A fourth intensity level will be added to increase the flexibility of the product. The current prototype features two intensity levels on the front and two on the back. Notably, artificial aging must be done to determine when the product should be replaced. As this current standard only operates over UV-A and UV-B, UV Innovations looks forward to developing a UV-C standard, as well as a larger format target.
The prototype of the Target-UV and UV-Grey cards were handmade, but the company hopes to overcome the challenges of large-scale production and distribution by Fall 2014.

42nd Annual Meeting – Paintings (Joint with Wooden Artifacts), May 31, “Painted Totem Poles at the American Museum of Natural History: Treatment Challenges and Solutions” by Samantha Alderson, Judith Levinson, Gabrielle Tieu, and Karl Knauer

Those who have beheld the Hall of Northwest Coast Indians at the American Museum of Natural History and its extraordinary “totem poles” will instantly recognize the potential scope of any study or treatment of such massive artifacts.

The Hall of Northwest Coast Indians, which opened in 1900, highlights the traditional cultures of the native peoples of North America’s northwest shores from Washington State to southern Alaska, including the  Kwakwaka’wakw, Haida, Tlingit, and others. (Source: AMNH.org)
The Hall of Northwest Coast Indians, which opened in 1900, highlights the traditional cultures of the native peoples of North America’s northwest shores from Washington State to southern Alaska, including the Kwakwaka’wakw, Haida, Tlingit, and others. (Source: AMNH.org)

These objects are housed in the earliest wing of the museum, curated at its inception by Franz Boas, “the father of American Anthropology”, who organized the early acquisitions of the museum according to a revolutionary argument: that of “cultural relativism” in opposition to a chauvinistic, social-Darwinist organization that put “primitive” peoples at the bottom of an evolutionary tree, the pinnacle of which was white America. Today, this hall holds a landmarked status and remains relatively unchanged, as the poles are very hard to move.

Ten years ago, a renovation of the hall was proposed. Although the recession thwarted plans, the objects were still in need of stabilization and aesthetic improvements. Because this project—from its inception, through the research, testing, and execution stage, was so expansive—Samantha Alderson reminded her audience that her talk could only represent an overview of a four-year process. Those interested in a specific aspect of the project can look forward to in-depth, forthcoming publications.
One of the more important aspects of the research phase, and a professional obligation that is indispensable to the curation and conservation of native materials, was the consideration of ethical issues and provenance information. Most of these pieces entered the collection between the 1880s and the 1920s, and the majority has been on continual, open display since their arrival. Their presence in AMNH’s collection is widely acknowledged to be ethically complicated in itself, representing an era of unscrupulous dealing in Northwest Coast artifacts. (To read more about “Indians and about their procurable culture,” consult Douglas Cole’s, “Captured Heritage: The Scramble for Northwest Coast Artifacts,” about the coincidence of a taste for these native artifacts and the establishment of many of the country’s foremost natural history collections. (p.xi)]
The carvings, including the carved columns most commonly described as ”totem poles,” would have had numerous functions within their originating cultures: house frontal poles holding entry portals to buildings, interior house posts, welcome figures, memorial poles, and mortuary posts [For a technical study on these types of carvings, please consult “Melissa H. Carr. “A Conservation Perspective on Wooden Carvings of the Pacific Northwest Coast.” Wooden Artifacts Group Postprints. 1993.].
To further hone their understanding of provenance, the 2009 CCI “Caring for Totem Poles” workshop in Alert, Canada, allowed the authors to travel through British Columbia with curatorial consultants, native carvers, and native caretakers, in order to study the techniques of manufacture. It was also important to keep abreast of the expectations of the native communities that might be borne out over the course of any treatment intervention or re-installation campaign.
The original aim of this project was to provide structural stability to those carvings which exhibited highly deteriorated surfaces caused by the weathering and biodeterioration in their original environment. These instabilities were often exacerbated by inappropriate environmental conditions and restoration interventions in the museum. The most significant issue requiring treatment was the presence of wood rot, insects, and biological growth, present in the original environment and continuing to run their course.
Although climate control was installed in 1995, soot from the age of coal heaters and lamps still blanketed the inaccessible areas of the objects. Dust from visitor traffic also dulled them, as the hall is adjacent to the entrance to the IMAX theatre. Routine and well-intentioned cleaning was ineffective against a century of accumulated grime and dust and was causing surface loss.
The location of the Hall of Northwest Coast Indians in relation to the IMAX theatre
The location of the Hall of Northwest Coast Indians in relation to the IMAX theatre

As there is no barrier between the objects and the visitor, touching has caused burnishing and scratching. The unfinished wood readily absorbs skin oils; and graffiti and adhered chewing gum had also become a most-unfortunate problem.
Early interventions after acquisition had caused condition problems of their own, as old fills had a hardness or density that is inappropriate for soft, weathered wood. These fill materials were only becoming more ugly, unstable, crumbly, and cracked with age.
All of these factors, taken together, provided a huge impetus for treatment.
To begin the treatment-planning stage, the conservators at AMNH performed examinations under visible and UV radiation and mapped the observed conditions and materials using a streamlined iPad-based documentation protocol. In some cases the restoration materials observed provided evidence of institutional and condition history. Although there were almost no previous treatment records of these objects, comparison with archival photographs of many of the objects showed the rate of deterioration since acquisition and provided clues as to dates of interventions and installation history.
In summary of the object-treatment stage, vacuums and sponges were first used in an attempt to reduce some of the dinginess of the surface and to increase the legibility of the painted designs. The many resinous and waxy coatings had trapped so much dust, however, that this treatment did not always have a satisfactory result.
The question of solvent toxicity held sway in all aspects of treatment, as operations were completed in makeshift spaces outside of the lab, due to the size of the objects; these areas had no fume-extraction infrastructure. Luckily, plaster fills could be softened with a warm-water-and-ethanol mixture and carved out.
Temporary conservation lab set-up in the gallery.
Temporary conservation lab set-up in the gallery (See treatment photo gallery here).

Butvar B-98 and Paraloid B-72 were selected as potential consolidants and adhesives. A 5-10% Butvar B-98 solution in ethanol (i.e. without the toluene component for safety concerns) was used for surface stabilization, and Paraloid B-72 in acetone was used for adhesion of splinters and detached fragments.
Karl Knauer filling splinter edges.
Karl Knauer filling splinter edges.

Fills were designed using different materials depending on the location on the object. These were intended to reduce damage during installation, display, and regular maintenance. If the fill was not visible, shapes were cut from Volara, beveled, and adhered in place with Paraloid B-72 along the edges. These were often necessary on the tops of the poles to cover the deep voids of deteriorated wood. Some losses were back-filled with tinted glass micro-balloon mixtures of different grades and different resin-to-balloon ratios where appropriate. As some paints were solvent-sensitive, certain fills required the use of Paraloid B-67. The final fill type was a removable epoxy-bulked fill to compensate for deep losses in visible areas. These areas were first filled with polyethylene foam to prevent the fill from locking in. The edges of the fill area to be cast were protected by tamping down teflon (plumber’s) tape which conforms nicely to the wooden surface. West System 105 Epoxy Resin—with “fast” 205, “slow” 206, or “extra-slow” 209 hardeners—was used in different proportions to 3M glass microspheres and pigments to give fill material with various hardness, curing-times, textures, and colors (See Knauer’s upcoming publication in ICOM-CC Warsaw 2013 for more details). This method is notable for its invisibility, its reversibility, and its rejection of phenolic micro-balloons, which are an unstable and unsuitable and were historically used for such a wood fill merely for their brown color. Once cured, the bulked-epoxy (and the plumber’s tape) were removed and the fills were then tacked into place with B-72 to produce an aesthetically pleasing and protective cap.
Many losses which were previously filled were left unfilled, as would have been the case it they had been collected and treated today. Crack fills were incised so as to retain the appearance of a (smaller) crack.
Once the surface and structure was stabilized with the consolidation and filling operations, the team turned their attention to the various paint films to be cleaned. Many of these were proteinaceous but some were more similar to house paints. This data was consistent with the ethnographic findings and with current native practice. No preparatory layers were used, and the pigment layers were often very lean.
PLM, XRF, and SEM-EDS, as well as UV-FL imaging, thin sections, and analysis with FTIR was undertaken. Some binder analysis was also possible, but this was complicated by historical treatments. Interpretation of epi-fluorescence microscopy results was also thwarted by the presence of multiple coatings, the inter-penetration, -dissolution, and bleed-through of layers. As many as four different types of coatings were identified, and understanding and addressing the condition issues caused by these coatings became a primary concern. Cellulose Nitrate was often applied to carvings in the early 20th century. Whether this was to refurbish or protect, it has developed into a dark-brown layer which is alternately hazy and glossy and which obscured the original surface appearance. Lower regions evidenced PVA or PVAc on top of the Cellulose Nitrate. Shellac and dammar are present in isolated locations, as is an orange resin which eluded identification (even when analyzed with GCMS).
Although identification of these coatings was attempted, removal was not originally planned due to the difficulties designing a solvent system for its reduction, considering the variation in sensitivities, the interpenetration of the layers, and the unknown condition of the original paint films beneath. This plan changed when the poles were deinstalled for construction.
The treatment design was largely aided by the isolation of four house posts in the collection made by Kwakwaka’wakw artist Arthur Shaughnessy.
Arthur Shaughnessy carving one of these poles (Photograph by George Hunt, copyright AMNH).
Arthur Shaughnessy carving one of these poles (Photograph by George Hunt, copyright AMNH).

Commissioned by AMNH in 1923, these had never been installed outdoors but which had been coated in the same manner and exhibited in the same space. This allowed for the development of controlled methods for coating reduction.
A Teas table (or Teas chart) was used to identify potential solvents or solvent mixtures, which were tested over every color and monitored for any leaching or swelling. These initial tests were deemed unsuccessful.
In areas without paint, film reformation with acetone reduced haziness or glossiness. Where the coating was completely removed, the wood was often left with an over-cleaned appearance which necessitated some coating redistribution with MBK, MEK, and propylene glycol. Wherever possible, gels were used to reduce the exposure to toxic solvents. In painted areas, the large variation in solvent sensitivity, the inconsistency of media binders, the varying porosity of the wood, and the changing direction of the wood grain required that the conservators work inch-by-inch. DMSO, a component of “safe” stripper, and NMP were controllable over certain colors but caused considerable swelling.
February 2012, the museum saw the reinstallation of the Shaughnessy poles, marking the effective conclusion of the testing period and the successful management of a challenging triage situation by conservation staff.

It was Kwakwaka‘wakw artists like Arthur Shaughnessy who kept carving traditions active when the Canadian government prohibited the potlatch ceremony in 1885. The ban was lifted in 1951, after AMNH’s acquisition of the house posts.
The completion of treatment represents an important opportunity to educate the public: Although these monumental carvings are exhibited in a historic wing of the museum, we need to dust them off and remember that these carvings represent very, active traditional practices and communities.
There is still the need to develop more systematic solvent strategies, as well as to consult with a paintings conservator. But it is clear that these objects stand to look much improved after the grime and coatings are removed or reduced and the objects are thoughtfully reintegrated with a well-designed fill system. Thanks to the remarkable talents of the AMNH team, these stately creations are finally commanding the respect they deserve.
Hall of Northwest Coast Indians :: AMNH
From the Bench: These Face Lifts Require Heavy Lifting :: IMLS
Arthur Shaughnessy house post carvings reinstalled following conservation treatment (February 2012) :: AMNH
Changing Approaches to the Conservation of Northwest Coast Totem Poles :: Reed College
Andrew Todd (1998). “Painted Memory, Painted Totems,” In Dorge, Valerie and F. Carey Howlett (eds.), Painted Wood: History and Conservation (pp. 400-411). Proceedings of a symposium organized by the Wooden Artifacts Group of the American Institute for Conservation of Historic and Artistic Works and the Foundation of the AIC, Colonial Williamsburg Foundation, 1994. Los Angeles: J. Paul Getty Trust.
A Brief History of the Jesup North Pacific Expedition :: AMNH