AIC Blog Archives: Conservators Converse
Former Blog of the American Institute for Conservation
The building conservation-program at Seinajoki University of Applied Sciences in Finland is threatened to be terminated. The program is the only one of its kind in Finland. Please sign a petition in which the Finnish section of the Nordic Association of Conservators pleads the decision-makers at Seinajoki University of Applied Sciences for reconsidering closure of the study program.
Read more: http://www.petitions24.com/vetoomus_suomalaisen_rakennuskulttuuriperinnon_puolesta
Gillian (with a hard “G”) is a conservator of interior murals and decorative finishes and presented beautiful images of a wide variety of 18th and 19th century American murals, with a deep appreciation of the special perspective of the conservator, given our unique level of access to these artworks. She began by relating this level of access to her experiences spelunking and finding herself in close proximity to spaces and places most people don’t ordinarily see – Werner Herzog’s 3d film of the caves of Chauvet came into the conversation here, with its attempt to give wider audiences that feeling of close contact, discovery, and the sense of actually being there.
American interior decoration of the 18th and 19th centuries is characterized by extensive interior painting. One of the artists Gillian focused on today was Edwin Howland Blashfield, who painted murals in both civic and ecclesiastical venues and had a particular technique of using rich layering on a monumental scale, producing a range of textures. In these murals, the distance of the viewer encourages the use of trompe l’oeil and other effects, which also have a significant impact when viewed up close. Blashfield was friends with Francis Davis Millet, another progressive muralist, and was a member of the group that founded the Mural Society of America in 1895. Many murals were produced as part of the “City Beautiful” movement, which promoted “beauty not only for its own sake, but also to create moral and civic virtue among urban populations.” Many neoclassical murals in public buildings were produced at this time, including Blashfield’s Power of Law in the Manhattan Appellate Courthouse, which was conserved in 2005 and is part of a mural cycle produced with other mural artists.
We moved next to the Essex County Courthouse where muralists Lowe, Walker, Turner, Cox and Blashfield painted a series of pendentives around the domes – Gillian noted that these were painted with extensive and subtle detail, even though it wasn’t necessary as they were viewed from a distance. These were cleaned in 2004 so the photo in the link above shows them rather at a worse phase in their lives…for better ones, look on Evergreene’s website.
St Matthew’s Cathedral in DC boasts a series of lunettes, painted in Blashfield’s studio and then installed afterwards, with more painting on site to integrate them. Here he used what was termed “percussive brushwork” (I don’t know where the term came from) using a large brush to “hammer” paint onto the surfaces, creating texture and movement. This was cleaned in 2003, removing surface dirt and grime. There was also apparently an early synthetic surface coating on these murals, which was analyzed at CCI; the murals are painted in oil on linen.
The Assembly Chambers in Albany NY display murals on stone by William Morris Hunt, which were partly covered by a ceiling installed less than ten years later. The mural “The Flight of Night” dates to 1878, a year before Hunt died in 1879; another is “The Discoverer”, dating also to 1878. He had produced many preparatory drawings and paintings as he had been working on this theme for decades; these as well as related 3d clay and plaster studies are in various museum collections. These paintings suffered from roof leaks, damage to the sandstone, salt formation, and most of all the use of paint materials incompatible with the substrate. Hunt may have been using “experimental” materials – he referred to a “secret recipe”. It seems that he was working in an oil-based medium. However, he did not put any preparation layer on the stone such that even while he was working, he noted that the stone absorbed the paint, leaving a more faded appearance the next day – in our terms, the stone had absorbed much of the oil binder, leaving a very underbound layer and precluding the formation of a stable oil film. Because of this “fading”, Hunt applied paint in multiple applications, but the underbound layers continued to fade and degrade over time.
At Rockefeller Center, the wall where Diego Rivera had painted his controversial mural (the one with Lenin), which was demolished in 1933, continued to cause problems with the replacement mural, called “American Progress” by José María Sert – problems which the conservators called “Rivera’s Revenge”. Here’s an NYTimes article about the conservation work there.
Because the architecture session had begun about twenty minutes late (the business meeting ran over) Gillian had to start to run through her remaining slides quickly at about this point. We saw Ezra Winter’s Fountain of Youth mural at Radio City Music Hall, and some wallpaper in the bathroom there designed by Donald Deskey, who was responsible for all the interior decoration of this building. We then sped over to the Pantheon de la Guerre at the National WWI Museum at Liberty Memorial in Kansas City, which is a cyclorama of WWI heroes which was painted in France and presented at the Chicago 1933-34 World’s Fair, then toured around the US (currently the subject of an exhibition). It was 402 feet long and 42 feet high. After the tour, the mural was largely forgotten and stored outdoors until Baltimore restaurateur William Haussner bought it at auction in 1953. In 1957, Kansas City artist Daniel MacMorris persuaded Haussner to donate the panorama to the Liberty Memorial Association, which acquired it with the okay to alter it to fit a new space; MacMorris “revised” it, cutting and pasting and adding more heroes. The last place we got to visit was Conception Abbey in Missouri, though I can’t tell you much more about that.
Looking up some of these sites online, I realize even more that it was a rare treat to see Gillian’s beautiful photos (I think she credited Whitney Cox with much of the photography) – there aren’t many images of many of these important works available, though often the Evergreene website has the best ones. Maybe some of the great images used in the presentation should be put online!
Amanda Norbutus is in the Preservation Studies doctoral program at the University of Delaware, and has her undergraduate and master’s degrees in chemistry. Her presentation first outlined the state of public murals preservation and the issues faced today, then described current research into protective coatings for public murals and discussed a case study of a mural by Meg Saligman in Philadelphia that has been successfully treated.
The “Contemporary Mural Movement” refers to public murals produced since the 1960s (see cool book) and Amanda noted that there are more than 350 public art programs across the US that have facilitated the production of these murals. The murals often address themes of heritage and social and political equality. Loss and damage are rampant for a number of reasons: the murals are often spontaneous, not planned with long term preservation in mind; they are subject to extreme outdoor conditions; and they suffer from a lack of funding – while money is pledged for their production, none is usually allocated for preservation. The murals often also fall under various jurisdictional disputes – no one is quite sure who is responsible, or who has the right to make decisions about the wall or the image. To address some of these issues, Heritage Preservation has a program called Rescue Public Murals which carries out identification, documentation and conservation of murals, provides a network for those working on their preservation and researching best practice for mural production and conservation, and conducts fundraising (you can sign up here to get on RPM’s mailing list). They also have a partnership with ARTstor Digital Library to preserve images of murals, as not all can be physically preserved; there is a Community Murals collection in ARTStor. Amanda noted one prominent case in which Ken Twitchell, an artist who had painted a mural (Homage to Ed Ruscha) on a federal government-owned downtown LA building, received a $1.1 million settlement after the mural had been painted over.
A few of the biggest problems facing murals are graffiti, physical destruction, and desaturation as the paint layers weather and are exposed to UV. UV radiation causes cracking, color change and fading. Oxidation chain reactions are the culprit on a chemical level. Research has been ongoing to look into protective UV barrier coatings. Some limitations are – scale, access, acceptability by stakeholders, safety (VOC’s), and ease of application. Some of the categories examined include acrylics, waxes, polyurethanes, and silanes.
In a study that began in 2005 at Delaware, Jessica Keister painted out more than 700 samples of blue, yellow and red colors of various types of paints from Golden, Novacolor, and Keim, in addition to some fluorescent colors. As coatings, she looked at B72 with Tinuvin, Novacolor, Golden MSA varnish, and a Triangle Triton coating (not reversible). The samples were placed on the roof and exposed to weather for three years. In 2008, Amanda began looking at the samples, noting the differences between colors – Hansa yellows did best – and paint systems – Golden heavy bodied acrylics did best. Golden MSA varnish seemed to protect the samples best – the Triangle coating was better at keeping mold and dirt off the surface, but its irreversiblity deducted crucial points from its usefulness. There was some success with B72 and Tinuvin (UV stabilizer), and in general two coats worked best of the protective layers. Amanda noted that products commercially sold as UV protective are not always so – she cited a test done by muralist Ed Massey on an industrial polymer coating that was purported to have a UV stabilizer, which failed completely. Finally, there needs to be more research into reversibility on a practical level, whether coatings can be effectively removed without affecting damaged paint beneath. Here’s more detail from Amanda about the parameters of the samples on an RPM blog post from 2008.
The Meg Saligman mural in Philadelphia is called Common Threads (1998), and when RPM assessed it in 2009 it was extremely faded. The artist didn’t want to repaint it, as she felt she would change it too much. Together with RPM and Winterthur Art Conservation faculty and students, the artist agreed to apply a coating of Golden MSA – but they had to get an exception from the EPA to use it on such a large scale. Applied after surface cleaning, this coating resaturated the colors significantly. They also then did some retinting with Sher-Cryl (Sherwin williams acrylic) and pigments (envirotint?) over the coating, then applied another layer of the Golden coating.
A key point is to work with muralists to prevent some of these problems from the get-go. Amanda noted that when doing this it’s important to address the bottom line – money – and emphasize that in the long run it is cheaper to use better products first rather than having to repaint or conserve a mural later.
She ended with a summary of other key points to remember when working with murals/muralists:
Historical considerations were of great importance for this restoration project and therefore the first part of the talk of Mrs. Alicia focused on them.
I found really interesting the account on the techniques that were behind the production of tiles. For this restoration work Mrs Fernández performed a very interesting research on XIXth century historical formulas for ceramic materials.
In a first stage of her research Mrs. Fernández studied original tiles which revealed to be composed of 56% quartz and 40% (mullite) porcelanite.
Mullite paper on original tiles was clear as it is a material that increases mechanical strength, thermal shock resistance and lows water absorption.
This research conducted the team to import stoke paste onTrent,UK. Original encaustic impression of tiles was substituted by a modern method of screen printing “enamel”, this was because of elevated cost, and long production time of the original techniques.
Coloration of tiles was produced with copper, cobalt and iron. Nevertheless this custom material is remarkable because of its physical properties while keeping aesthetical characteristics of the original tiles. At this point of the talk Mrs. Fernández distributed among the participants at her talk, some samples of this material. I highly appreciated this gesture, as it allowed us to have first hand information about material properties.
What astonished me the most was the performance of Mrs. Boan team work: in only a few months they were able to reproduce XIXth century techniques for ceramic production, then they were able to mixing them with modern imprinting techniques to produce a custom material, wich lead to a fast and great restoration job.
This talk presented how the works of restoration and conservation in the Inca, 1000 years old Temple of Pachacamac were conducted. The importance of this temple relies in the fact that is the only temple with painted designs in its walls besides the fact that it was one out of the two oracles in Inca times.
The main guidelines for this project were 2: maximum research and minimum intervention.
Research stage focused on several aspects:
Regarding the interventions they were focused on the conservation of:
What I appreciated the most of the work of Miss Pacheco is the respect of original techniques employed by Incas, which are sustainable, and that up to now had proven to be effective, and unlike to promote microorganism colonization as one might think. Her work raise some interesting questions about the green pigment used on paintings, and its identification is still to be made. I will definitely follow up the progress of these works at the Pachacamac Inca Temple with a lot of interest.
Doug Porter, of the University of Vermont, teamed with Angelyn Bass, of the University of New Mexico, to present their recent work at Bandelier National Monument in New Mexico. Their project began as a structural monitoring program, in collaboration with MIT, and Angelyn first walked the audience through the computer modeling investigation of a particular section of rock. The modeling was meant to investigate structural stability, collapse scenarios and potential failure points. Doug then discussed the geological formations at the park and the presence of a clay & calcite deposition in combination with biofilm colonization which the team thought could be providing structural stability and weathering resistance to the tuff rock. Their site investigation included absorption tests for those areas covered with biogrowth in comparison to recently exposed surfaces. They also looked at permeability and erosion resistance. The presentation acknowledges that biogrowth is identified as a deterioration process in most cases, but may also be contributing to the preservation of the substrate.
Emily Aloiz presented a recent treatment investigation to address blistering and delamination of earthen finishes at Mesa Verde National Park in Colorado. Her study continues the work begun in 1994 at this site by Professor Frank Matero and the graduate students of the University of Pennsylvania program in Historic Preservation. (http://repository.upenn.edu/hp_theses/178/ ) The need to identify an adhesive which would re-adhere delaminating earthen finishes within the alcove sites of the park was guided by a desire to be respectful of the site’s Native American culture by choosing a natural product. Other parameters which were identified included: practical, inexpensive, non-toxic; durability in an outdoor environment and compatible with sandstone and earthen materials; re-establishes adhesion; retreatable; and versatile. Laboratory tests were conducted on a group of proxy samples using a food-grade gelatin as well as the gelatin with the addition of glycerine. Emily carefully laid out the methodology followed during these tests to analyze bond strength, changes due to freeze/thaw and wet/dry cycles and humidity fluctuations. Because the gelatin is organic, biodeterioration was also a concern and was addressed by placing petri dishes of the gelatin solutions at the site as a monitoring system. Once laboratory tests confirmed the feasibility of the use of these gelatin solutions, treatment was carried out in situ by syringe injection between the earthen finish and the substrate. Where there was carbon soot present on the surface, it was first treated by applying cyclododecane as a spray.
This paper shares a testing program that incorporated the use of phosphate solutions to create a mineral coating (hydroxyapatite) on stone to impart strength and durability. The project goal was to consolidate the surface of weathered stones (primarily calcareous stones were tested) to prevent loss from dissolution. Naidu shared that the idea of this testing program came from natural patinas (phosphate and oxylate-based) that can be observed on stone surfaces. Calcium phosphate and hydroxyapatite (main inorganic component of teeth and bones) were analyzed.
Testing was conducted to react a phosphate source with calcite (carrara marble used), and diammonium hydrogen phosphate (DAP) was selected for further analysis through SEM/EDS and XRD. Variables of DAP concentrations (1m and 2m) and exposure times (12 hours and 24 hours) were analyzed. SEM images were used to evaluate film formation, and it was found that after 24 hours of 1M DAP concentration exposures that a dense film was created on the stone’s surface. Raising the concentration to 2M created a denser film, though spalling was evident. XRD confirmed the presence of apatite in the film.
Studies also found that during the process of converting minerals the porosity of the stone increased and further testing should consider adding calcium back into the stone. SEM analysis was used to evaluate the addition of calcium ions back into the samples, and the most coverage was seen with calcium chloride at a 1M concentration. Naidu also mentioned a study by Snethlage that reported success of converting minerals using ADP. This testing will continue and explore external ion additions and sequence transformation, control films, and comparison of effectiveness with calcium oxylate.
Naidu discussed the process of consolidation using silicate-based systems, pointing out that sometimes coupling agents such as tartaric acid are used to assist bonding. A comparison study was designed to evaluate Conservare OH100 and 1M DAP on artificially weathered limestone (heat was used to induce damage to samples). The consolidants were applied and the tensile strength (all samples) was tested at 2 days (DAP 25% increase) and 4 days (DAP 28% increase). The results indicated a greater improvement with DAP treated samples. This testing will continue and explore the effect of calcium ion additions, organic additives and extending samples to marble. Tracking the progress of this continued testing will be important, since there are relatively few stone consolidants on the market that meet current environmental and safety standards.
This talk presented an approach to fountain care that is preventative, focusing on maintaining an ideal water chemistry to prolong the life of fountains and associated mechanical systems, plumbing and artwork. Krueger presented a process for treatments to fountains, particularly when biogrowth is observed. Prior to treating water chemistry, Krueger recommended draining the water and mechanically cleaning the elements with a surfactant and clean water, taking care to rinse thoroughly.
Fountains must then be re-filled and if using a municipal water source it is likely that minerals and organic matter must be addressed, while a distilled water source may require addition of minerals. Krueger explained the concept of water saturation, and that unsaturated (soft) and supersaturated (hard) water both create problems either with leaching or precipitates. Water saturated of minerals is ideal, and pH and water temperature both affect saturation as well. Krueger recommended the Taylor Brand test kit, which is available at commercial pool/spa supply stores, to assist with balancing and monitoring water chemistry.
Regarding biogrowth, he explained that additives such as silver/copper, chlorine and quaternary ammonia all can effectively control growth but can cause issues such as staining, deterioration of mechanical systems and water foaming. Poly-quats act as blocking agents in swimming pools and ponds, and Krueger recommended its use for controlling bacteria and fungi. Filters help maintain water chemistry and control biogrowth by limiting nutrients available in water. Krueger explained that oligotropic water is ideal (trace amounts of minerals Ni, Zn and Cu), and that controlling phosphate levels is recommended to limit biogrowth.
A series of steps were presented for checking levels and making alterations to the water chemistry. 1- Make visual observations, as the presence of a slippery surface can indicate the beginning of growth. 2- Test water (phosphate levels, temperature, and level of polyquats which requires a special kit). If high levels of phosphates are found then it can be remedied by draining some water and refilling it (if under 125ppm) or using a chelating agent and then backwashing (if over 125ppm). To adjust alkalinity, sodium bicarbonate can be added in small quantities and checked every 24 hours. Then total dissolved solids (hardness) should be tested and followed by checking calcium carbonate hardness, keeping in mind that calcium hypochlorite should not be added to adjust, rather by draining some water and adding new. Finally the overall saturation should be checked. 3- Inspect mechanical equipment. Filters should be inspected per manufacturer’s instructions. Krueger shared that he is researching the practice of adding barley straw in water, as there is published data that supports or disputes its ability to eliminate algae by releasing peroxides in the water.
This talk focused on research studies of biodiversity and treatments to control biogrowth on fountains, thus slowing the deterioration of stone. Cuzman explained several factors that affect micro-environmental conditions including: water regime (continuous or sporadic), materials (intrinsic properties), location (colonizers) and treatments (to water or fountains). Four fountains were selected in this study – two in Florence, Italy and two in Grenada, Spain (Patio de la Sultana and Patio de la Lindaraja). Microbial diversity of the colonized surfaces (green algae, cyanobacteria, and diatoms) was identified on the surface, forming a complex structure (biofilm); DNA sequencing was used to characterize sampled biofilms, and similarities were found between the two different geographic areas.
Regarding removal of biofilms, mechanical removal or water treatments can be effective. For this experiment a chemical treatment was also explored by adding an antifouling agent to a commercial waterproof coating (Wacker Chemie AG, SILRES® BS 290). Antifouling agents considered include: poly-alkyl pryidium salts, zosteric acid, capsaicin, and algophase.
Two fountains were selected for treatment (Tacca’s fountain in Italy and Patio de la Lindaraja in Spain), and both fountains were drained and mechanically cleaned. Afterwards, the modified waterproof coating was applied and allowed to cure for two weeks before adding water back to the fountains. Both fountains were visually observed, and at four months slow growth was observed, while at six months significant green growth was observed. Sample analysis from both fountains found a decreasing number of colonizing organisms, so even though growth was observed the diversity of organisms in the biofilm was affected. Cuzman found that the treatment only affected specific colonizers and that the unaffected ones flourished with less competition. Research on this subject will continue, perhaps modifying the antifouling agents (amount or types) added to the coating.
