Category: Specialty Sessions

Posts on talks that were presented as part of the specialty sessions at AIC’s Annual Meeting

39th Annual Meeting – Architecture/Research and Technical Studies Joint Session, June 3, Consideration of Infrastructure in the Assessment of Historic Fountains by Thomas J. Podnar

Thomas J. Podnar opened with a picture of an anonymous fountain to illustrate the beauty of these structures and their ability to bring beasts together (displayed by horses drinking from the fountain). The talk consisted of three case studies which are summarized below.

The Probasco Fountain in Cincinnati, Ohio (c. 1887) was the subject of the first case. The fountain consists of Quincy granite with a polished bowl and a bronze top. The fountain was located precariously close to an existing roadway, and Podnar was hired to evaluate the condition of the fountain and explore the feasibility of moving it to a safer location. During an investigation of the interior cavity, he found a water main running through the chamber and an electrical box, which was added for display lights. Research of historic photographs revealed that the water display had been diminished and that it was missing elements such as drinking cups. In the end the city decided that it was cheaper to move the alignment of the road (slightly), and the fountain remains in the original location.

The second case study subject was the Athena Tacha in Cleveland, Ohio (c. 1985). The stepped granite fountain was designed to be ½ wet and ½ dry (the latter for students to perch upon). After running for eight years, the fountain was shut off due to issues with water leaks. A condition assessment found that the adhesive sealant, used to control water, had failed and resulted in water leaking to the dry side. Mineral deposits were also found on the stone’s surface, other conditions included broken pipes, corrosion, and inadequately sized equipment. The client also shared photos taken during the installation process, and Podnar noticed that it was the middle of winter. Low temperatures had also caused poor bonding of the stone to the continuous mortar bed. A full re-installation and equipment upgrade was recommended and subsequently executed. Stones were removed and labeled, and when re-installed provisions were made for water seepage to flow to the pool (at the base) and stainless steel clips were added to reinforce connections. Custom-fit pieces of sheet metal were installed to separate the wet and dry sides. The mechanical system was fully replaced (upgraded) and the access grate was designed to match the existing (granite) in galvanized metal, rather than stone, to facilitate maintenance with a lighter unit.

Voyage of Ulysses on Sixth Street in Philadelphia (c. 1977) was the subject of the final case study. The stainless steel fountain was fabricated by Lippincott and designed by David von Schlegell. During the condition assessment, Podnar found that the clear coating (applied to the metal’s surface) is failing and that the water display has been diminished (when compared with historic photographs). The fountain installation is located over a parking garage, and is leaking into it. The mechanical system consists of separated pumps for the two different display elements (high water throw on one side and a continuous waterfall on the other). Other findings include that the screen strainer has never been removed during maintenance and that over the years pumps were replaced with smaller ones. Podnar shared historic photographs taken during fabrication of the artist testing the water flow at Lippincott, emphasizing the importance of water flow in this fountain’s design. Conservation treatments are planned and have not yet been executed.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Acoustic Emission for Tracing Damage Directly in Works of Art” by Lukasz Bratasz

Acoustic emission measurements use microphones, amplifiers, and computers to detect and record the release of elastic waves during stress relaxation processes within materials, such as crack propagation at both the macro and micro scales. This talk discussed how acoustic emission (AE) has been used to track these processes in wooden and stone objects under varying levels of relative humidity and outlined how such studies have been used to generate and validate RH guidelines.

During AE experiments, the microphones are positioned against objects mechanically, without the need for glues or clamps, and environmental noise can be determined when there is sufficient distance between two sensors. It is important to note that recording AE monitors internal stress-relieving processes in real-time but is not able to predict when damage may occur.

The AE from wooden cylinders was found to depend on both the change in RH and the rate at which this change occurred. Mild changes in RH applied over 48 hours, for example, did not lead to detectable acoustic emissions. Monitoring the AE of a wooden altarpiece in a church lead to the establishment of expanded RH guidelines of 35 – 60% RH.

AE studies have also been performed on clay-containing sandstones similar to those found in medieval cathedrals. The studies monitored the sandstone’s response to damaging wetting-drying cycles and detected a linear AE increase with the number of cycles. The results of this study, in conjunction with predicted climate data, were used to anticipate areas of Europe in which clay-containing sandstones may be at particular risk for damage.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Listening to Art: An Exploration of the Use of Photoacoustic Infrared Spectroscopy in the Forensic Analysis of Artists’ Pigments” by Ian Butler

Dr. Butler described in this talk the potential use of Fourier transform photoacoustic infrared spectroscopy (FTIR-PAS) to identify organic and inorganic pigments. In their commercially available device, the sample is placed in a gas filled cavity and exposed to periodic flashes of infrared light. The sample absorbs the radiation and heats up, causing the surrounding gas to expand. The expansions can be detected as sound waves by a microphone at the end of the cavity.

The technique has been used to obtain reproducible IR spectra of pure pigments in the range of 400 to 4000 cm-1 with a resolution of 8 cm-1. Samples from lab-prepared frescoes have also been analyzed. In some cases the background noise from the plaster overwhelmed the pigment spectra, but in others the spectra could be used for pigment identification. Dr. Butler mentioned the possibility for depth-profiling, which may allow for more complex samples to be analyzed. Such work has not yet been carried out.

This method can also add some useful peaks to a regular FTIR spectrum, making it another useful option in conservation science’s identification tool-kit. Only small samples are needed and minimal preparation is required, an advantage over the commonly used ATR (Attenuated Total Reflectance) technique that may call for the sample to be crushed.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Medical Computed X-Ray Tomography and Volumetric Reconstruction for the Technical Examination of Organic/Composite and Ceramic Objects” by JP Brown

This talk presented case studies to demonstrate the application of computed tomography (CT) scanning to archeological objects. According to Dr. Brown, CT is usually available in most hospitals and can often be used for free in the evening. JP recommended first taking a regular x-ray of the object to elucidate its general construction. He did not go into details about the technical aspects of CT and image processing; however, this topic was covered by Hai-Yen Nguyen’s talk earlier in the session (An Open-Source Workflow for the Visualization of CT Data in Art Conservation and Archaeology).

Resolutions of 0.3-1.0 mm can be obtained by CT. The results are presented in Hounsfield units (HU), a scaled measure of the attenuation of radiation due to the material. Water is defined to have 0 HU, while air is defined to have -1000 HU. Typical HU values for metal and bone are 3000 HU and 1000 HU, respectively. Many image-processing techniques, such as the application of false-color, rely on the different HU values of different materials.

Case 1: Animal mummy

The CT images clearly showed that a piece had been inserted into the mummy, probably to hold the head at a desired angle. The detail obtained of the skeleton allowed for the species to be identified as a type of gazelle common in Egypt.

Case 2: Polychrome Japanese sculpture

The CT showed the grain of the wooden object in great detail, enough that non-invasive dendrochronolgy could be possible. This piece demonstrated the problem of having highly attenuating materials in the object – the bright images caused by leaded glass eyes obscured some of the nearby details. However, false-color rendering was able to show areas of gesso and older conservation treatments on other areas of the sculpture.

Case 3: Moche pottery

One of the aims of this study was to check for the presence of organic residues inside the vessels. This was done by comparing the HU values of the pots to those obtained from samples of various modern food residues. Although the CT of one of the pots did not indicate that food residues were present, the image showed a pattern of holes suggesting that the vessel was designed to produce sound from blowing air. A second pot was simply a conch shell, and the CT confirmed the expected internal structure. Interestingly, material inside a third pot did indeed exhibit attenuation values matching those of the test food samples. The material was subsequently collected on a swab, and SEM images indicated that the organic material was likely charred plant stems.

Case 4: Restored archeological stucco (possibly Sasanian)

The sculpture depicted the head of a king. The crown portion of the object, the shape of which could be used to identify the specific king, had been largely restored. Although it was possible to visualize only the original material by manual segmentation of the restored portions, not enough of the original remained for the identity of the king to be determined.

Several interesting points were raised during the question portion of the talk. It is known that x-rays affect the results of thermoluminescence (TL) dating, though it is not known to what extent. As a precaution, JP recommends removing a sample before CT scanning if TL may be performed later. Another interesting question regarded recommendations for approaching a hospital. JP suggested contacting the chief radiologist first, or ideally, finding a teaching hospital with a research radiologist. He mentioned that eventually an administrative/financial person will also need to be contacted and that having an exciting story about your proposed work will increase the chances that the hospital allows use of their CT machines.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “An Open-Source Workflow for the Visualization of CT Data in Art Conservation and Archaeology” by Hai-Yen Nguyen

This talk discussed how open-source image-processing software can be used to manipulate data obtained from computed tomography (CT) scans of objects. In this technique, radiographs are taken around an axis of rotation, and the three-dimensional volume of the object is virtually reconstructed. From JP Brown’s talk (Medical Computed X-Ray Tomography and Volumetric Reconstruction for the Technical Examination of Organic/Composite and Ceramic Objects), we learned that it is relatively easy to gain free access to CT equipment at local hospitals. However, as  Hai-Yen pointed out, the proprietary software for processing the data can cost around $15,000. By using several open-source programs, she and her co-workers were able to obtain quality images highlighting various aspects of the object under study.

CT images of a corroded metal artifact in a tub of water were presented at various stages of processing with different software programs. A median filter was applied in ImageJ to reduce noise. Most other processing applications were performed in ImageVis3D, including thresholding, slice analysis, and manual segmentation. The 16-bit raw tiff file formal was considered the most user-friendly for transfer between the software systems.

After the initial data processing, Hai-Yen demonstrated the use of false color to clearly show different types of material and used clipping (masking) to isolate certain features. Once a complete 3D rendering is obtained, it could potentially be used to create a physical model of the artifact without the need to dry out and clean the original.

Disclaimer: Neither of us bloggers has ever done CT or this type of image processing, so we may have missed salient details. Feel free to add information in the comment section below.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Silver Nanoparticle Films as Sensors to Measure the Emission of Sulfur Gases from Wool Fabrics Degrading Under Ambient Conditions” by Rui Chen

Dr. Rui Chen has been developing optical sensors using silver nanoparticles for the detection and quantization of sulfurous gases. These sensors are meant to serve as an improvement over the metal coupons used in the Oddy test, as silver nanoparticles react faster and with higher sensitivity than bulk silver. Additionally, their reaction with hydrogen sulfide causes the nanoparticles to lose their color, so the kinetics of the reaction can be monitored spectrophotometrically with the decrease in the absorbance spectrum.

To make the sensors, spherical yellow nanoparticles are assembled as a monolayer on a glass surface with a polyethylenimine linker. When the monolayer films are exposed to hydrogen sulfide gas, the observed decrease in absorbance is faster when the concentration of hydrogen sulfide is higher. At concentrations of 10 ppm hydrogen sulfide, for example, the reaction is complete within about an hour, while completion occurs within 4 to 6 minutes at concentrations of 100 ppm.

Furthermore, Dr. Chen has found a linear relationship between the first-order rate constant for the reaction and the concentration of the gas. Thus, an unknown concentration of hydrogen sulfide gas can be calculated based on the reaction rate observed between the gas and the nanoparticle-based sensor.

The sensors have been applied to wool samples aged under UVB light. These samples exhibited the highest emissions within the first 400 hours of aging, with concentrations of hydrogen sulfide reaching nearly 600 ppb per gram of wool. The sensors have also been applied to photograph cases and a box containing naturally aged silk fibers; four of the five objects tested exhibited some emission of hydrogen sulfide to give concentrations that ranged from 33 ppb to about 150 ppb. Future work on this project will involve the development of a user-friendly protocol for the application of the sensors.

39th Annual Meeting – Research and Technical Studies Morning Session, June 2, “Measuring Changes in the Appearance of Surface Textures” by Paul Whitmore

The ability of conservators to accurately describe surfaces is integral to effective documentation and communication in the conservation field. While changes in color can be accurately described by the Munsell and CIELAB systems, changes in the appearance of a surface texture are often described by vague and indefinite terms. The work described by Dr. Whitmore arose from the desire for a new vocabulary for describing the surface texture and appearance of regularly-patterned surfaces such as canvas. His talk presented a background of how we perceive surface texture and some mathematical analyses that can be performed to yield qualitative metrics for describing certain textures.

Texture is not only an artifact of the topography of a surface, but also a result of the illumination of this topography; the appearance of a surface depends on the position and directionality of the light source as well as the distance of the light from the surface. As viewers, we perceive texture from the resulting distribution and contrast of light and dark areas.

The limitations of our perception can be mapped by a contrast sensitivity function, which relates our ability to perceive patterns of varying degrees of contrast with the size of the pattern and the distance at which it is viewed. Changes to texture are often accompanied by changes in contrast; a weathered surface, for example, exhibits decreased contrast between its light and dark areas. In periodic patterns, the contrast can be quantitatively measured by a gray-level correlation matrix analysis. Once this contrast value has been determined, the contrast sensitivity function can be used to calculate the maximum viewing distance at which a pattern of the given contrast can be perceived. This “maximum visibility distance” may serve as a useful metric with which to describe periodic surface textures.

The analysis has been successfully applied to canvases that had been subjected to extreme treatment, and further work will examine the degree of textural changes caused by common conservation treatments. Future work may also investigate other mathematical and image processing analyses for application to different surface textures.

39th Annual Meeting – OSG Morning Session, June 2, “The January 12, 2010 Earthquake in Haiti: Building a Conservation Foundation from the Ground Up” by Stephanie Hornbeck

Stephanie Hornbeck, Chief Conservator for the Smithsonian Institution Haiti Cultural Recovery Project (CRP), presented a paper on the conservation recovery efforts in Haiti in response to the January 12, 2010 earthquake. There was much information in the paper, requiring that the presentation keep a fast pace throughout. The slideshow itself primarily consisted of photographs of the work areas, conservation projects, and the many people who have been involved in the CRP. Stephanie Hornbeck prefaced the presentation by saying that many of the aspects of the Smithsonian Haitian response apply to any issue in conservation so that the impact of the project and resulting paper could extend beyond emergency response situations.

The cultural devastation response was dependant on several other factors, including the immediate human recovery response, the pillaging of art and objects, and salvage efforts. The severity of destruction and the restrictions on any recovery efforts based on logistics mandated that priorities be established, a task dependent on the Haitian officials. From this, it was determined that three sites in Port-au-Prince should receive immediate attention: the National Palace (see image below), the Holy Trinity Cathedral (Brief Look at the Holy Trinity Cathedral), and the Musée Nader (see also: http://online.wsj.com/article/SB10001424052748703837004575013022647688144.html). These three sites exemplify the cultural heritage of Haiti, both in their construction and in the works therein contained. Here, Stephanie Hornbeck briefly elaborated on the city in an art historical context, touching on the pre-colonial traditions, the effects of European contact, and the establishment of Port-au-Prince as the ‘Centre d’Art.’ It is this history and culture that the CRP was so interested in recovering and preserving to the best of their abilities. The original team of professionals involved in the efforts has since expanded, but some of the key names include Richard Kurin (Under Secretary for History, Art, and Culture), Corine Wegener, and Olsen Jean Julien (project manager and minister of culture). The AIC joined the partnership, facilitating the sending of several volunteers throughout the course of the project, running May 2010 to November 2011.

According to the Institut de Sauvegarde du Patrimoine National (ISPAN), over 50,000 works of art were damaged as a result of the earthquake. All of the conservation efforts must be undertaken in Haiti, a consequence of the colonial history of the country. The weight of this falls fully on the CRP; however, they must operate out of the central storage area and the availability of materials is severely limited. Equally challenging is that no one in Haiti was previously qualified in conservation. Thus, a large portion of the CRP has been training individuals in the practice so that educated efforts may continue following the project’s close. In 2010 the chief conservator was chosen, Stephanie Hornbeck having been selected. She established the project’s plan, which was to follow a course similar to: stocking, assessing, methods, oversight, stabilization, training, and treating works of art of a high cultural value. By first identifying colleagues and then training, the project would then be best equipped to respond.

At this point in the presentation, several examples of the damage were provided as well as a discussion of the ensuing challenges. These were as follows:

  1. The issue of education. Specifically, Stephanie Hornbeck said that many of the Haitians involved were expecting complete restoration and that the concepts of stabilization, prioritization, and the intensity of the time commitment were difficult to communicate.
  2. The absence of records and/or photos, as well as complete inventories.
  3. The environment, including the lack of screens, the instability of electricity, and the tropical climate.
  4. Antiquated restoration materials and methods.
  5. The necessity of importing 100% of the material supply.
  6. Recovery efforts could not begin until five months following the earthquake.

Attempting to respond to these challenges as best as they could, the CRP developed a local infrastructure consisting of both CRP staff as well as local associates. In order to achieve this, an ICCROM course was held during August and September of 2010. Professionals with an academic background in art or chemistry were selected for participation, resulting in twenty-four Haitian managers studying painting, object, and paper conservation. The next course will provide an introduction to collection databases. From here it is hoped that the individuals may continue on to received graduate training in conservation and maintain the execution of the practice in Haiti.

Developing the local infrastructure comprised only part of the ‘identifying colleagues’ task. The AIC volunteer conservators were another essential component, as well as the three contract conservators hired by the project. Over the course of the project to date, over thirty-two people have volunteered their time at an estimated value of $115,000. Aside from practicing conservators and assistants, another category of colleague needed was in supply acquisition. Approximately $45,000 worth of supplies were purchased and hand carried by various participants to Haiti. As none of the supplies could be purchased in Haiti, this was an essential step. The supply list itself has continued to develop throughout the course of the CRP as various conservators and participants help to refine it.

Following ‘training,’ the task of adequately responding became the primary focus. It was immediately obvious that security was a big issue. As just one example, many of the stained glass elements had already been stolen from the National Cathedral. Thus, the team made a red-list of high priority items in September 2010. Though nine months since the original earthquake, time was of the essence as items continued to be stolen. The red-list communicated the objects that were at the greatest risk in terms of security and each was processed by priority according to the individual circumstances. In terms of the manner in which work has been approached, it is a three-part process. First, condition assessments must be completed so as to provide the data necessary for future work. Next, interventions occur in order to improve the current housing and storage environments in order to stabilize the works in question. Finally, the treatments occur, though the emphasis continues to be placed on stabilization above all else. One of the most common treatments being performed is the removal/treatment of mold and dirt accretions. Items of the highest cultural value have received the highest level of conservation treatment; however, the process is highly time consuming and limits the amount of work that can be done in other areas.

At this point, Stephanie Hornbeck provided specifics as to the processing and treatments that have occurred at the sites of the Holy Trinity Cathedral and the Centre d’Art. At Holy Trinity, there was a large mural cycle originally consisting of fourteen murals, though now only three remain. With two conservators and four assistants, the remaining murals were consolidated and successfully effaced and stored. They are now waiting for the cathedral to be rebuilt, at which point the murals will be reinstalled. At the Centre d’Art, individual works were recovered within the first month following the earthquake; however, the manner of recovery was not ideal. No inventory could be completed during the process based on time constraints and the lack of an inventory from which to base their identifications. Also, storage was difficult in the time of great turmoil so two large, metal containers had to be used to hold everything that could be recovered, which ended up being approximately 5,000 pieces. Once the metal containers were filled, they were guarded twenty-four hours a day; however, they also had to remain on the street from January until August, reaching approximately 80% rh. At this point, the works are being processed methodologically and being stored in more suitable means while they await any treatment.

From these experiences and others, two case studies are currently planned. One would focus on looking at an on-site recovery effort where bulldozers and shovels were used to help look for art, resulting in the recovery of approximately one hundred and fifty pieces. The second case study will examine the storage of the works in the metal container. These pieces underwent triage from the 3rd – 6th of September, where it was discovered that mold was the primary side effect of the storage, requiring that the processors where personal protective equipment.

To date, the CRP has stabilized over 5,000 works of art while the process has cost approximately $1.5 million. The team has greatly grown; however, they still need materials, funding, and assistance in training qualified associates. It is also becoming pressing that Haiti determine if they can build a local core with which to continue the preservation efforts. The CRP is currently a finalist for a global ambassador’s grant, which would provide the much needed funding if it is selected. Following the presentation, one question was asked regarding the possibility of training in the use of alternative, local materials and methods of conservation. Stephanie Hornbeck responded by saying that it really was not possible to use any local material of any sort as nothing as of close enough quality but that they are currently working on obtaining a local supplier of conservation-grade material.

 

See Also: http://newsdesk.si.edu/releases/smithsonian-develops-haitian-cultural-recovery-project

39th Annual Meeting – Book and Paper Session, Wednesday, June 1, “The Hours of Catherine of Cleves: Exhibition, Conservation and Analysis of an Illuminated Manuscript,” Francisco Trujillo, Morgan Library

Francisco Trujillo’s talk was an excellent addition to the overall conference theme of ethical considerations and critical thinking as it highlighted the impact a conservator’s assumptions and biases can have on the course of analysis and treatment. He described the treatment of a Dutch illuminated manuscript, The Hours of Catherine of Cleves, in preparation for exhibition at The Morgan Library and Museum.  The Book of Hours contains over 150 illuminated miniatures designed and painted by an artist known as the Master of Catherine of Cleves. The manuscript was originally bound as one volume, but was later split into two volumes and reordered. Treatment of the manuscript involved disbinding, consolidating the media on each page (with 1-2.5% isinglass in water and ethanol), and rebinding the folios in their original order.

As treatment progressed, Trujillo began noticing the presence of a non-copper based “smooth blue” pigment, possibly ultramarine. The “smooth blue” was found on pages that would have been facing each other in the original manuscript (before it was split and reordered) and was not found on surrounding pages. FCIR and XRF  analysis revealed that ultramarine was present in these “smooth blue” areas along with azurite. Trujillo began to wonder if the Master had selectively used ultramarine on a handful of leaves, possibly mixing it with azurite, or if the ultramarine had been painted on top of the azurite, a later “sleight of hand”? Since at this point Trujillo had no other evidence that the Master ever used ultramarine, he assumed that the presence of ultramarine was a result of 19th century “touching up” when the manuscript was split into two volumes.

Trujillo pursued the “sleight of hand” line of inquiry, but then came across evidence that perhaps the Master of Cleves had, in fact, used ultramarine as an aesthetic choice. This led him to once again question his beliefs about the Master’s working methods; though there was evidence that many of the leaves had been “doctored” when the manuscript was split, there was also evidence that the blue pigments were mixed, quite possibly by the Master. He also found cobalt mixed into to some of the blues, and now leans toward the belief that it was the Master himself who used ultramarine on a select number of folios.

Trujillo did a nice job of calling attention to the assumptions conservators make about the objects they’re working on and the impact this can have on treatment decisions. He acknowledged that pursuing the “sleight of hand” theory – while fascinating – diverted his attention for a while and kept him from seeing other important evidence in the manuscript.

39th Annual Meeting, Book and Paper Session, Wednesday, June 1, “The Watercolors Of Charles Russell: An Examination Of The Artists’ Materials And Techniques On The Montana Frontier,” Jodie Utter, Conservator of Works on Paper, Amon Carter Museum of American Art

In preparation for a 2012 exhibition of Charles M. Russell’s watercolor paintings, Jodie Utter, Conservator of Works on Paper at the Amon Carter Museum of American Art , undertook an investigation of the artist’s techniques and materials. I really enjoyed this presentation; I knew nothing about Russell or his work prior to the talk and Utter was successful in sharing her excitement about the artist by putting together an interesting narrative of his life, process, and development as a painter.

Russell was born in St. Louis in 1864, and moved to Montana as a young man to work on a sheep ranch and then as a night wrangler on a cattle ranch.A self-taught artist who began drawing and painting in his spare time on the ranch, he began painting full-time in 1893. A turning point in Russell’s career was a trip to New York in 1903-04, where he met and was influenced by the work of other painters and shifted from working in transparent watercolor to opaque watercolor. He produced over 1400 watercolors in his lifetime

Utter visited Russell’s still-intact studio to take samples of his paints, which she analyzed using polarizing light microscopy and x-ray fluorescence; as a point of comparison, she also analyzed samples of contemporaneous paints from unopened tubes.  Materials found in his studio reveal that Russell used the highest quality brushes, paints, and papers available to artists in the American West in the mid-19th century. He used red sable brushes, the handles of which he cut and whittled to points in order to shape paint layers (he also chewed on his brushes, as evidenced by all the teeth marks!). The most common paint found in Russell’s studio was Chinese White watercolor, introduced in 1834 as the first reliable opaque white. Utter also found many paint tubes in Russell’s studio; she highlighted how revolutionary paint tubes were for artists at that time (introduced in 1840), allowing them to purchase high quality paints in large quantities. Also, since tube paints have more body than pan paints, they could achieve different results.

Infrared examination of Russell’s paintings revealed that the underdrawings of his earliest paintings were “overdrawn” – he was drawing figures over and over again, including lots of details, trying to “get things right,” without erasing much. Later underdrawings were much more minimalist – confident sketches with little detail. His color palette evolved from very basic to more developed – in a 1897 painting, there were 17 different colors of transparent watercolor in use –  to a sophisticated use of complementary colors. Russell was introduced to color theory during his visit to New York; afterwards, he began using less black in the dark areas of his paintings – shadows were created with combinations of blues and greys. Russell used traditional watercolor techniques, like layered washes and  scrapping away paint layers to achieve highlights, but he incorporated many unconventional techniques as well. Russell was also an oil painter and a sculptor and he adapted techniques  – most notably, impasto – for his watercolor paintings.