The subject of this talk was the treatment of the bronze statuary in Central Park, in specific the monument to King Jagiello (and despite the guided group-pronunciation lesson, no, I cannot say that properly – sorry Matt!). The overall project has a huge scope, as the bronzes were coated with Incralac in the late 80’s/early 90’s and have not been on a proper maintenance schedule, as is required for that type of treatment. The Incralac has cross-linked and begun to obscure the detail of the statues, and the old method of abrasive coating removal has not been good for the statues.
In order to complete the project in a timely fashion, dry ice blasting was determined to be the best course of action. The cleaning had to go hand in hand with addressing structural issues, as King Jagiello had already been noted to be unstable in 1984. The mounting issues were brought up again in 2009, and a process of removing and shoring up the base was completed in 2016. One of the most interesting parts of this, to me, was that a votive plaque of Saint Claire was found inside the sculpture – who knew that public monuments would have such things? The structural stability was improved, and the weepholes were cleaned and enlarged in order to address drainage issues and issues with active electrolytic corrosion cells.
Matt provided a number of technical details about the dry ice set-up, which I won’t reproduce here (but I suspect will be in the postprints), but I found especially useful, as I have been looking into dry ice cleaning for my own projects, and am interested in the baseline that others have established. He also provided a great overview of what you need to set up a dry ice system – the compressor, the dryer, the unit itself, and a hopper with dry ice. The cleaning itself went exceptionally quickly, with complete coating removal in six days! Dry ice cleaning also helped the team achieve their campaign goals of sustainability and reduction of hazards. During treatment, noise level and air quality readings were taken to monitor the health and safety aspects of dry ice cleaning, which is an important factor that many seem to overlook. The treatment was completed with re-patination, a final steam clean to remove residue, and application of a hot wax coating.
I appreciated this talk for the great general overview of the ins and outs of a dry ice cleaning campaign, and I’ll be applying what I’ve learned next summer – and reaping another benefit that Matt pointed out, as the cool mist produced by cleaning definitely helps the conservator cool off on a hot summer day!
The subject of this talk was the treatment of “Flak Bait”, a World War II B26 Marauder at the National Air and Space Museum with an impressive track record – 207 missions with no crew loss, the only remaining B26 from the Normandy landings, with its original paint intact, though a green and grey overpaint had been added when it originally was put on display. The aim of the treatment was to make the aircraft look exactly as it did at the end of the war. This included not only the painted surfaces, but the doped fabric elevators, rudders, and ailerons, which were the main focus of this talk.
The doped fabric sections had historic patches, from repairs made while the aircraft was in use, as well as post-historic tears. Traditionally, doped fabric parts of aircraft are re-covered, rather than repaired, and the art of doing so is maintained by the aircraft maintenance restorers at the NASM. In order to preserve the “patina of use” of the object, this standard approach would not be an option. Lauren opted to explore different treatment options, and opted to look at how known methods from paintings conservation could be applied to this project, as the doped fabric had a lot in common with a painting on canvas. The eventual treatment involved careful facing of the material and removal from the frame, followed by cleaning thoroughly to remove ingrained dirt and mold. This worked largely according to plan, with one issuee when the stabilized fabric was returned to the frame – the repair of a major tear had allowed 0.5% shrinkage over the length of the object, causing significant registration issues. Eventually it was possible to relax the fabric and return the object to an acceptable position on the frame. A resin coating applied over the surface successfully shifted the color from chalky yellow back to the original olive green, addressing another overarching issue of the treatment, maintaining uniformity of appearance over the entire object.
The part of this talk that resonated the most with me was the discussion of conservation versus restoration, especially when restoration practices such as re-covering doped fabric aircraft are “celebrated practices”. Another presenter also made this connection – Davina Jakobi, in her talk on conservation of ship model riggings, quoted Lauren and expressed that she had found the same challenges in deciding to repair rather than re-rig. Navigating these ethical questions can be tricky territory, but when handled with grace as both Lauren and Davina did, can provide great results. Lauren counted the improved collaborative relationship between conservation and restoration as one of the main benefits of this treatment, along with the development of new methods to save an ephemeral material, and I would have to agree.
This talk, given by Dawn Wallace, caught my eye because it focused on a treatment that I had heard of, but largely amongst doll collectors, not amongst conservators – and I had never had the guts to try it! The use of acne treatments, such as gels containing salicylic acid and benzoil peroxide, to reduce or remove copper staining has really interesting potential, but was not previously well-tested. Dawn treated various PVC dolls (including Barbie!) and completed analysis using pyrolysis GC/MS, XRF, and mass loss/mass attenuation. The results showed that for most gels, there was movement of copper within the stain, although with some there were changes to the plastic makeup. The salicylic acid did remove copper, but showed a slight weight gain rather than a weight loss – pyrolysis GC/MS then confirmed that a residue had indeed been left on the surface. The benzoil peroxide showed significant weight loss, but had its downsides as well.
Although this was a quick talk (15 minutes), I found it very informative and enjoyable. I would have liked to see more visual comparisona of the before and after treatment, as I wonder if the success in removing the stains is enough to make it worth pursuing removal of the residue as an additional treatment. I will be interested in any future research into this treatment!
Right off the bat, Dr. Corbeil noted that the title of the talk should probably be a question rather than a statement, because nobody has all of the answers, and this talk was not going to be a definitive guide to conservation science. She noted that conservation science still has some issues – it can be very expensive to complete scientific research projects, and thus there is a reliance on government funding, which can be fickle in a number of ways. Through these challenges, Dr. Corbeil’s aim was to show how the CCI operates, raise questions about the efficiency of the approach, and understand how best to ensure maximum impact for conservation science.
The CCI has three main categories of work: research and development, expert services, and knowledge sharing, all of which are interconnected, and which relate to the community that CCI serves. Dr. Corbeil spoke specifically about a number of examples of this work, including dripping paint on works by Alfred Pellan; authentification of works by Jean Paul Riopelle in conjunction with the Getty; fading paint on Rothko murals; and various pesticide surveys of textiles.
Of these cases, the Rothko question had interesting implications. With the Rothko, the institution asked for the analysis to be completed, and result showed the presence of a fugitive pigment. A monitoring program was enacted in response to this. Dr. Corbeil mused on a few topics – was the analysis really necessary, given that many Rothko works have these fugitive pigments? Would the exhibition decision have been different without analysis? Is the monitoring necessary, given that degradation of these fugitive pigments is inevitable?
The pesticide surveys also brought up an interesting chain of discussion, involving the repetition of analysis for different clients. If enough data has already been collected to generate guidelines and predict the results of surveys, is it necessary to continue to analyze separate collections? Dr. Corbeil noted that it has been an inescapable fact that people want to test their own collections, even if previous applicable results are available. This is not necessarily a bad thing, but it also points to the idea that services rendered for one client may be broadly applicable, and that dissemination of results will always be significant.
Dr. Corbeil concluded that the key elements for success involve choosing the right research question, engaging in collaboration, transparency in methodology, and effective dissemination. Within this context, one of her previous statements resonated with me – she stated that results are disseminated “in the traditional way” at CCI. I wonder if there is a benefit to looking into non-traditional routes for the sharing of knowledge, since that is one of the areas Dr. Corbeil indicated was most important for the success of conservation science? I look forward to future discussion of this topic, and the bright future of conservation science as a whole. Keep up the great work, CCI!
A problem encountered in the study of paintings is distinguishing the medium in which they were created, and delineating layers which may include different media of mixtures of media. This was the subject of a paper presented at the Research and Technical Studies session.
It is not easily possible to distinguish between oil paintings and tempera (egg-based) paintings by eye, or using many analytical methods. The authors discussed the benefits and drawbacks to three main types of analysis that are used within paintings conservation: cross-sectioning, Fourier-Transform Infrared (FTIR) spectroscopy, and thin layer chromatography (TLC). FTIR, for example, cannot distinguish between egg proteins and glue, and the results can be masked by pigments or colorants. None of these methods, as discussed, can be definitive when it comes to mixtures of media such as tempera grassa.
The author also considered the effectiveness of other common methods, such as GC/MS (Gas Chromatography – Mass Spectrometry). The main drawback to this is that results cannot be compared across different experiments if the methodology varies even slightly.
The combination of these drawbacks in common methodologies led the authors to pursue Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), a high-resolution technique that is better at separating and identifying fragments which are different but have similar masses. It also allows for the presence of specific compounds to be ‘mapped’, giving a helpful visual of layers and levels. Using this method, they were able to map for amino acids, identifying the presence of animal glue in a mixture. Practically, this was shown to differentiate between a gesso-size ground and the glue layer which was determined to have been purposefully added.
The talk concluded with a reminder that this technology, as with most, works best in conjunction with other methodologies. While this is an important point to remember, the potentials of this technique are exciting. I’m very interested to see the potential that this technique has for three-dimensional objects with multiple painted or gilded layers. I hope that someone pursues this, and that the technique is able to be harnessed across conservation disciplines.
Preventive conservation was the topic of much discussion at this year’s annual meeting, from how to teach it to what exactly it entails. In this talk, Stefan Michalski discussed the quantification of preventive conservation.
He began by reminding us that we base our ideas of preventive conservation on the “proofed fluctuation” argument: if fluctuation in the past has not caused significant damage, then similar future fluctuations will not either. He also defined preventive conservation. First, we assess risks. Then, we ‘treat’ risks; this second part is Preventive Conservation. We have to remember that ‘treat’ has a different meaning in this context than in remedial conservation, and despite being a loaded word, accurately describes what we do. These definitions are simultaneously straightforward and complicated; we struggle with them and yet we need them for our daily work.
Michalski continued by defining the four steps to successful preventive conservation:
1. Identify Options
Steps 2-3 require quantification, and it’s vital that this quantification is transparent and well-documented. This is where Michalski and Karsten’s research comes in. They assessed the financial risk of every preventive option available for a variety of institutions, including an archive and a historic house.
In order to quantify reduction in risk, calculations were made using the following formulas:
- Option effectiveness = size of risk reduction = size of original risk – size of reduced risk
- Risk reduction / cost = [% of collection saved / $ spent] /year
I had never encountered this calculation before, or considered this as a feasible method of determining cost-effectiveness and ranking options, and I don’t think I’m alone in the conservation field in this. I wish that this had been covered by one of my graduate courses, because while it may seem obvious in some ways, the explanation was exceptionally helpful, and is something that I will take to my professional practice.
The numbers produced graphs on a logarithmic scale, in terms of percent saved per dollar. By evaluating options on this scale, it was possible to see how cost-effective various options are. What was highlighted with this calculation is that the cost effectiveness of an action is a function of the magnitude of risk – the bigger the risk, the better the return on percentage saved. This is in line with the economic principle of ‘economies of scale‘. What Michalski noted was that it is important to remember that the scale referred to is internal, not external, which means that small museums can be just as cost-effective as larger museums.
I loved this talk, and I felt like I learned a huge amount about quantification of risk. ‘Risk assessment’ is a term that we are all familiar with; to be able to go more in-depth is a skill, and Stefan Michalski did an excellent job of teaching that skill. His results are hugely applicable to museums and institutions of all sizes, and we should all learn and apply this method to aid in our decision-making for preventive conservation.
This talk revolved around the Whitworth Art Gallery, part of the University of Manchester in the UK. I was interested in this talk in particular because I was interested to see the differences between UK and US approaches to sustainability, and to see how sustainability measures against other principles such as access and recommended storage conditions.
One of the central themes of this talk was that “access is central to all of the gallery activities”. This resulted in some interesting decisions, which strike a balance between practical and ideal. One that stuck out to me personally was the presence of an IPM working group which meets weekly, to discuss what needs to be done in order to ensure that events like festivals and those involving food can be pulled off. Their maintenance of a ‘can do’ attitude is inspiring, and ensures that the museum works with it’s surroundings – a park, which families want to be able to visit and enjoy in tandem with the museum.
The process which the museum went through in order to add an addition to the building was also discussed. A few points stood out there, as well:
– A new route was introduced to separate catering delivery from art movement and delivery (which is also related to the IPM working group).
– A green, bio-diverse roof was put into place on part of the building.
– Stores were relocated into a basement, where the environment can be controlled with passive techniques rather than air conditioning.
– Solar panels were added to the roof.
– Daylight was introduced into some galleries.
– A ground source heat pump was installed.
The idea of the green, bio-diverse roof was fascinating. In order to prevent it from drawing unwanted pests into the museum, they worked with entomologists to ensure that they only attracted specific insects – those who don’t want to eat their lovely textile collection. The introduction of daylight into galleries as discussed here formed a funny comparison to another talk given on sustainability and environmental consciousness.
Another aspect to sustainability was also discussed: the development of working patterns which allow the collection to be feasibly managed and kept in the best condition. One of the theories they work under is known as the Pareto 80:20 principle, which says that 80% of results come from 20% of issues, or in this case, 20% of objects. They use this principle to target their work-flow, focusing on the 20% which give the most result and working on the other 80% on a “modular” basis.
This cross of sustainable environment and sustainable work practices extends to the methods they use to package their 2D objects, as well. This category of object is packaged in a way that it can be easily switched from storage to display or vice versa, and the packaging provides a buffering layer that reduces the need for strict environmental control.
I would have loved to hear more about these storage/display procedures, as I think they could be useful for other museums. I’m also curious to have a more specific list of the plants they used in their bio-diverse roof garden, because that too could be useful in other places. Their practices seem to be very widely applicable, and their attitudes towards having a museum that works for the public and within its environment are admirable. I would love to see other museums adopt these approaches, to be environmentally friendly and to sustain the working environment of conservation professionals.
This technical talk discussed a new method and material for architectural conservation. Norman Weiss began by addressing the problems of lime grouts, and the nature of metakaolin. The problem of lime grouts is the anaerobic nature of the area the lime is being applied to, as the lime requires carbon dioxide from air for the setting phase of the lime cycle. Metakaolin is a class N pozzelan, a ‘thermally activated clay’, where dehydroxylation is accompanied by a loss of crystal structure. Metakaolin is between fumed silica (0.3 µm) and Portland cement (5 µm) in terms of particle size. Metakaolin is very quickly and specifically dehydroxylated between 500 and 530 degrees Celsius, a process which Weiss noted you “don’t have to finesse”.
Weiss continued by addressing the purpose of pozzelans within architectural conservation. The material must densify and fill gaps, must strengthen in order to create bonds, must reduce the amount of cement needed, and must reduce the amount of ‘bleed water’ in order to be the most desirable pozzelan possible. Metakaolin has the potential to achieve all of these goals, if used in a specific way.
This material has been previously looked at somewhat, the first study having been completed in 1993, and the commercial introduction of the material in 1994. Weiss also noted that there has been a lot of research into metakaolin as a grout in Portugal.
Metakaolin has a high water demand, and is not great for a grout, as it does not set well; in order to function, it requires a superplasticizer. Weiss and his colleagues have experimented with the reaction between lime and metakaolinite, which forms Straetlingite. What seemed to be the most important part of this talk was the discussion of the new methodology that Weiss and his colleagues have developed and patented using this material. The wall is mechanically stabilized, and the void is filled through a tube. This method gives the material the time necessary for the slow-strengthening material to achieve the necessary strength.
It will be interesting to see in the future the results of further study and case studies of completed projects using this material and methodology.
The involvement of source communities and practices that allow conservation to be sustainable within communities are hot topics in conservation right now, and Giovana Jaspersen presented a very interesting case study that covered both of these topics in the Opening Session of the AIC Annual Meeting 2014. She discussed the ways in which her team engages with Mexican communities, spaces where religion is a center of social life, and objects of worship are in frequent use.
The objects themselves were beautifully painted sculptures, which would be paraded around and put on display within the religious community. Jaspersen noted that previous restorations had been undertaken on some objects, using non-conservation friendly materials, such as automotive paint, which apparently imparts a high gloss that is seen as desirable.
She noted some significant problems in approaching these communities about the conservation of their objects, the most important being the challenges of communication. Other questions included ongoing conservation – how do you ensure preservation after the conservator has left the community?
Using a number of different approaches, from initial immersion to assistance and then intervention, she was able to develop a methodology which utilized a number of different media to engage and teach the community – lectures, plays and skits, brochures, and involvement of children in the community.
A number of themes seen in this talk were repeated in other talks and discussions, and are really important things for all conservators to consider. Reaching out to children is a great way to ensure that the conservation profession is sustained in the future, and engaging with conservation students ensures that the message about community involvement is spread among professionals.
Overall I really enjoyed this talk, and I think the most important takeaway was the statement that our profession is not just about material conservation, but sociocultural conservation. The only way we can achieve that is by projects such as this one!