Month: May 2012

AIC’s 40th Annual Meeting, Revisiting Suction Table 101: Getting the Most from Your Table, Workshop by Robin Hodgson. May 8, 2012

Anyone who has seen either an RH Conservation Engineering tool or met Robin Hodgson in person will first be hit with a sense of inimitable style, and then realize what precision and detail underlies that surface. I’m not sure when I realized Robin gave workshops, but found myself quite jealous of some lucky student’s write up of theirs – probably at Winterthur some time ago. Writing from the perspective of a book and paper conservator of some 15+ years, I have worked in a number of labs with a variety of inherited suction equipment and tools ranging from the crafty conservator lab-made early designs, to Rube Goldbergian attachments, and early production models from Museum Services Corporation. Many inventive conservators have created interesting adaptations and and suggested designs along the way. Facing mechanical burnout on my current table that served my lab well for many years, I have been realizing that it is not enough to simply think the mechanicals are the only variable that cause a table or tool to work well – often the operator needs an upgrade too! With this in mind, I joined the workshop hoping to get some better understanding of the systems available and how they are used most efficiently.

Robin is a practicing conservator of wooden objects and furniture in Australia, and strove to develop a new range of tools after parting from conservation school, investing at least 5 years in product research development and design. While RH Conservation Engineering is one well known brand, a great effort was made in the workshop to discuss designs from other manufacturers with a non-competitive tone. In fact, Robin’s kind words for colleagues in the same market and openness to their work and innovations was a great pleasure, because this spoke more clearly to the participants’ needs for working and getting the best out of their current machines.

To a mixed audience of paintings, objects, textile and book, paper and archives conservators, Robin presented the technology and factor variables behind and the differences between such tools as hot lining suction tables, cold tables, and high pressure small machines such as fritted disc or other spot vacuums. This was extra useful from my perspective, to hear how different specialties approach the use of these. Hot lining tables were not traditionally part of my toolbox, but as book and paper, and especially photograph technology changes in contemporary art, I think we will be seeing more use and adaptation of these tools across specialties in the future and so found it exceptionally useful to understand the difference.

I was expecting more terrifying charts, graphs and calculations (perhaps a hangover from my training in interpreting HVAC controls, ASHRAE standards and hygrometric charts), but Robin sensibly minimized the use of complex physics and presented clean design/engineering specifications that showed the essential workflow of these types of machines, and where they can go wrong, or be improved. Some relative terms were discussed to better understand the language used in atmospheric pressure (hectopascals (hPa), (inHg), millibars (mb) and torr) so that participants could navigate from one manufacturer’s machine or country’s standard to another. Simple concepts and familiar tools (home vacuums) were used to relate comparable pressures available based on the sizes of the suction device.

Robin answered the participants’ many questions readily without needing to cut into the planned time for the hands-on workshop, especially considering my many probing questions, since blogging for others was on my mind! In retrospect, I now wish I had asked more about the workings of dipole and blower motors, horsepower, and how modular one can get with components. I certainly did get my money’s worth and look forward to improving performance on my table and devices when I get back to the lab, and recommend this workshop to any starting or mid-career or long time conservator.

Some links that may be of interest:

http://www.jstor.org/stable/3179681

www.rhconservationeng.com/

http://jeffpeachey.wordpress.com/2009/04/02/thin-profile-suction-platen/

http://www.museumservicescorporation.com/equip.html

www.willard.co.uk/suction-equipment

http://universityproducts.ecomm-search.com/search?keywords=suction&submit.x=0&submit.y=0

40th Annual Meeting, Wooden Artifacts Session, May 11 “Training the Next Generation of Furniture Conservators”, Mark Anderson, Steve Brown, MaryJo Lelyveld, Jonathon Thornton, Antoine Wilmering, Debbie Hess Norris, Moderator

This was a panel discussion moderated by Debbie Hess Norris on where the future of furniture conservation training lies. WAG Program Chair Stephanie Auffret began the discussion by describing the current situation, in which very few students are being trained in furniture conservation in the US currently. In preparation for the discussion, Stephanie sent a questionnaire to the panel participants, current educators in furniture conservation, and current practicing furniture conservators. The questionnaire asked about expectations of core competencies for recent graduates in furniture conservation, opportunities to develop these competencies, and where potential employment opportunities for recent graduates might lie. The questionnaire identified a broad range of core competencies which a recent graduate in furniture conservation ought to have, including knowledge of the history of furniture, a scientific understanding of wood and other materials used in furniture making, good hand skills, knowledge of preventive conservation and documentation, as well as a structural understanding of furniture.

The panelists then gave very brief presentations. Steve Brown, professor of furniture making at the North Bennet Street School in Boston, MA, described the furniture training program, which includes knowledge and handling of hand and power tools, and a progressive series of furniture making projects, including a tool chest, a chair, a table and a case piece. He showed typical examples of furniture made by NBSC students, and described the emphasis of the program on developing hand skills.

MayJo Lelyveld described the absence of furniture conservation training opportunities in Australia, and described how most conservators tasked with caring for furniture there have come from othher areas of specialization and have had to develop their skills on their own, or from non-conservators with knowledge of woodworking techniques. For treatments involving a high level of woodworking skill, they have to turn to these non-conservators to participate in the treatment.

Mark Anderson then briefly talked about the furniture major at WUDPAC, describing how few majors there have been in recent years. WUDPAC requires that its furniture majors demonstrate a certain level of competency in wood working, a requirement that does not exist for any of the other majors. WUDPAC has graduated very few furniture majors since this requirement was instituted, illustrating that it is very difficult to assemble all the prerequisites at a sufficiently high level of achievement to get in to Winterthur and also gain experience in cabinet making.

Ton Wilmering talked about some of the training programs in Europe, and that they exist at more varied academic levels, briefly discussing his own training.

Jonathon Thornton talked about the Buffalo program, indicating that they train furniture conservators their as well. He emphasized that good hand skills were important for ALL conservators, and that developing them in one area or another could come a little later in a conservator’s training.

Debbie then opened the discussion up to the floor, and my ability to take careful notes took a back seat to my interest in the conversation. The following is more my impressions of the conversation than a strict recounting. Tad Fallon pointed out that the first CAL class occupied many of the institutional positions that are still available, and that the institutional job opportunities haven’t been that great. Jonathon Thornton said it’s like the pig in the python (or something like that), a big bulge in the middle, but it’s skinny at both ends! Steve Brown said that a visitor to NBSS once commented that she wished she had a job which didn’t require any thinking, illustrating an attitude about furniture making which is all too prevalent (sometimes even among other conservators, and especially other museum professionals, in my opinion).

The discussion seemed to center more and more around whether and how much training in furniture making a furniture conservator needs. Jonathon Thornton pointed out that furniture conservators have a host of tools, techniques and materials available to them not typically used by the traditional furniture maker, including casting in polymers and digital reproductions, which conservators do and should use. Ton Wilmering related the discussion back to the wood panels of panel paintings. He described that many museums (and conservators) accept cracks in panel paintings when they would never accept tears in easel paintings. He thinks this is because the conservators responsible for the panel know they don’t have the wood working skills to repair the crack.

Mark Anderson again discussed Winterthur’s difficulty in finding students with the preparation necessary to get in to the program and the woodworking skills necessary to major in furniture, and suggested that students didn’t need to arrive at Winterthur with those skills, nor did they need to go to NBSS to get them. There was some discussion from the floor that areas of subspecialization (marquetry, carving, etc) are not usually perfected by even those students who DO have wood working skills before they get into school. Others pointed out that much of the work done by most furniture conservators involves surface treatment rather than structural work. I believe a largely unspoken, but underlying current in the discussion, was that there are not a large number of institutional jobs in furniture conservation in existence in the US right now. Mark did say that an institutional job was the ambition of most conservation program students. This may be part of the problem in recruiting students into furniture conservation, but the problem will only compound itself when current institutional furniture conservators retire and their institutions are unable to find people trained to replace them. The positions will be eliminated and there will be even fewer jobs available, and more furniture collections will be in the care of people without the training to undertake complex treatments.

Debbie wrapped up the discussion by suggesting that WAG needs to plan a way forward. She had a wide-ranging list of suggestions. Perhaps WUDPAC could send potential furniture majors to NBSS for the summer between their first and second year, as they are currently doing with some book and paper majors to the NBSS bookbinding program (an idea which occurred to me as well during the discussion). WAG might undertake demographic studies about where furniture conservation positions exist, and how close those in those positions are to retirement. The data collected could be used to help develop grant proposals to improve the professional development opportunities for various woodworking skills. She encouraged discussions between WAG and FAIC to work on developing more PD courses. She also suggested that WAG hold a roundtable discussion among furniture conservation educators, both US and international, to discuss current practices and how things might be developed, and how job opportunities might be increased. She offered that WUDPAC and Winterthur would be willing to host such a discussion. Debbie being Debbie, she left us all feeling hopeful for the future, with a renewed sense of purpose and willingness to roll up our sleeves and get cracking. Let’s hope we can build some momentum and accomplish some of the things on Debbie’s list of suggestions.

40th Annual Meeting, Objects Session, May 11th, “The Treatment of a Mi’kmaq Box Made of Birchbark, Porcupine Quills, and Iron-Dyed Spruceroot”, Carole Dignard

The multi-step treatment of a Mi’kmaq birchbark box was outlined in this talk presented by Season Tse. The circular box with four stacks of rings is made of birchbark and decorated with dyed spruceroot and porcupine quills. Before treatment, it was exhibiting significant instability due to a deformation of the lid, the separation of the rim from the lid, and localized deterioration of the dark brown dyed spruceroot. There were also reported losses in the birchbark, unknown instability of dye components to light, losses to the spruceroot, and overall surface dirt.

The treatment began with a cleaning of the quillwork with saliva. This step revealed the brilliance of the blue-dyed quillwork and the presence of yellow-dyed quillwork previously unnoticed. The sensitivity of the dyes to light damage was tested using microfade tests with a Blue Wool dye scale ranging from 1-8. The dyes were found to between 3-4, which indicates that the dyes would survive 100 years at 50 lux for 8 hours a day before noticeable fading occurred.

The lid of the box was deformed and warping. After testing using deformed samples of birchbark, they found the appropriate solvent and pressure parameters to treat the deformity. A methanol vapor chamber was used under 6 psi vacuum conditions for three days to reform the lid. The treatment was mostly successful though some springing occurred.  Broken spruceroot was stabilized, paper pulps fills were used for the loss of birchbark, and the lid was attached to the rim with Japanese tissue paper hinges.

The investigation and treatment of the dark brown colored spruceroot could be considered the highlight of the talk. Through their investigation into the colorants of the material they found that the colorant had both iron (II) ions and tannins present. This combination has been reported time and again as the source for severe deterioration of dyed cellulosic material. The concentration of iron (II) ions were identified and monitored throughout the treatment with iron indicator paper. To stabilize this deterioration they choose calcium-phytate solution, developed by CCI, to complex with the iron thus arrest the oxidation of the spruceroot material.  Because the box could not be immersed in to the solution the application was with brush. After each application the ion content was monitored. They found that five applications were enough to stabilize. However, the application of the solution was not without complications and risks. The spruceroot swelled during the application and staining of neighboring spruce root occurred due to migration of the iron ions.

 

 

 

40th Annual Meeting, Wooden Artifacts Session, May 11 “Conservation Training at the Forbidden City”, Antoine Wilmering

Ton Wilmering, Senior Program Officer at the Getty Foundation, spoke about the the World Monument Fund’s new conservation training program it has developed at the Forbidden City in Beijing, China as part of its collaborative conservation program for the Qianlong Gardens in the Forbidden City. The gardens, a series of 27 pavillions and courtyards built by the Qianlong Emperor between 1771 and 1776 within the Forbidden City are an extraordinary example of Qian Dynasty decorative arts, and reflect the emperor’s broad cultural tastes and knowledge. I had the privilege of seeing the traveling exhibition of furniture and other objects from the Qianlong Gardens at the Peabody Essex Museum in Salem, MA in 2010, and the furniture and interiors on view were beautiful, exhibiting incredible craftsmanship.

The World Monument Fund is focused on funding projects with capacity-building components, and in conjunction with their conservation program in the Qianlong Gardens, in 2009 they established an new training program in the Forbidden City known as Conservation Resources for Architectural Interiors/Furniture and Training, or CRAFT. The program is designed to provide on-the-job training in both traditional craft practices and modern conservation techniques and science. Participants were selected from among current staff members of the Forbidden City complex, and include carpenters, collections care specialists, curators, architects and scientists. Current craft practitioners in China often have little knowledge of past techniques or history, and the program was designed to introduce them to craft history using historic Chinese cabinet making manuals. The program focuses on critical thinking as well as hand skills, and areas of study include scientific principles, history of conservation ethics, worker safety, drawing and drafting using both traditional and CAD techniques, materials technology, tool making, and joinery.

The program has made efforts to include Chinese faculty wherever possible, and Chinese wood species specialists and organic and inorganic chemists have taught in the program. The WMF found that many of the resources and people needed in the program were available in Beijing (in fact lots of conservation literature has been translated into Mandarin), but the WMF needed to make the connections with local libraries and scientists to bring them into the project. Other participants in the training program have included Susan Buck (cross-section analysis), and Chris McGlinchey (adhesives), and Behrooz Salimnejad (gilding) among others, as well as Ton, Rick Kershner and Greg Landrey, who the WMF brought in initially to design a space for the program and develop the curriculum.

Ton pointed out that the furniture on view in the traveling exhibition from the Qianlong Gardens which came to the US had not been worked on by participants in the CRAFT program. Instead, the Forbidden City bureaucracy had contracted out the restoration of that furniture, and it often involved practices that conflicted with modern conservation ethics. I was interested in the cultural differences exhibited by the Chinese participants. Ton told how the students all liked to work together on a project, showing a picture of four students sitting around a table, cleaning it with swabs together.

Ton also talked about the difficulties the program has experienced. Because the participants are employees working in the Forbidden City (remember, the program is on-the-job training), they are frequently called away to their regular jobs, which can be disruptive. Continuous supervision of the program by a trained conservator has also bee difficult. Many of the original participants have had to – or have chosen to – drop out, and currently about half the original class are still participating. Interestingly, it is the carpenters and architects who have stayed, not the collections care specialists.

After talking about the CRAFT program, Ton briefly discussed another initiative the Getty Foundation is involved in, to facilitate the transfer (and retention) of skills and knowledge in the structural conservation of panel paintings. Many of the most skilled practitioners in the conservation of these wooden panels are approaching retirement age, and the Getty Foundation has begun a 6 year initiative to set up apprenticeships with these practitioners for post-graduate, mid-career and senior conservators of wooden artifacts. The program is designed to have a broad geographic distribution, to include participants in Eastern and Western Europe, as well as the US and UK, presumably.

 

AIC’s 40th Annual Meeting – Objects Session, May 11, “Made in L.A.” by Rachel Rivenc

The original topic of this talk shifted from the analysis of sculpture created by the “Finish Fetish” artists using ATR (attenuated total reflection) to a discussion of the materials and methods of fabrication employed by three of these artists: Craig Kauffman, John McCracken, and Larry Bell. Though not accepted by the artists themselves, “Finish Fetish” was a name bestowed upon a group working in the L.A. area in the 1960s referring to the cool, yet pristinely finished surfaces that were characteristic of their art. Rachel noted that care must be given to preserving the signature surfaces, thus any analytical investigations required the use of non-invasive techniques only. The materials examination was augmented by interviews with artists when possible, as well as archival documents.

Craig Kauffman, one of the first artists to use plastics in the L.A. art community, converted industrial fabrication methods into his practice. Heavily influenced by Marcel Duchamp, his early work involved painting, typically with clean lines, on the back of acrylic sheets composed of poly(methyl methacrylate), confirmed by ATR analysis. By 1964, he had begun shaping the acrylic sheets by vacuum forming, collaborating with a manufacturer. The acrylic was heated in an oven until it softened, then shaped on a mold to create shallow reliefs. Kauffman’s sketches reveal plans for fiberglass molds with wooden supports, which were especially necessary for his later experimentations with depth and complexity. The transparent shells were subsequently painted, using thick rubber masks to create crisp lines. Later, he created a feathered look by spraying the paint over a cardboard mask, which served to soften the lines. He eventually shifted from solvent-borne acrylic-based paint, an ethyl methacrylate/methyl acrylate co-polymer, to nitrocellulose paints, since the solvent-based paints caused the substrate to craze and crack.

Rachel went on to discuss the technique and materials of John McCracken, who is reported to have said he wanted his sculptures to look as if they were “made of color.” They generally consisted of wooden planks coated in a layer of fiberglass, followed by a primer and various layers of paint, later switching to polyester resin application instead of paint. To make grooves in the surface, he would mask the lines with painter’s tape, then coat exposed surface in the polyester resin mixed with pigment. He consistently jotted down ideas and sketches before producing technical drawings, and even kept a notebook recording the varying temperatures and amounts of catalyst used for the resin as he experimented, making note of how it affected the working time, as well as the properties of the resulting work. Regardless of the conditions, the application of resin to the surface of the planks required an experienced and steady hand in order to avoid the evolution of bubbles in the resin layer (as any novice conservator embedding their first few paint samples for cross-sections knows!). The final step involved sanding of the surface to a smooth sheen.

The last artist Rachel broached was Larry Bell, who worked not with plastic, but with glass. Originally a painter, he would add mirrors to his compositions to introduce volume, eventually deciding that he wanted to work exclusively with volume. He worked often with plywood, mirror parts, and paint, though he increasingly favored glass, such that his paint became instead the effect of light as it was manipulated by the glass. In 1962, he began experimenting with the vacuum deposition of thin films to the glass, soon after which he bought a secondhand machine to execute the process himself in 1966. This purchase allowed him the freedom to create larger panels, which also corresponded with a shift into more environmental art. The vacuum chamber heated the metal under vacuum to a temperature at which the metal vaporized and was deposited on the surface of the glass as a micron-thin film. The three metals most commonly used by Bell were aluminum, silicon monoxide, and nickel-chromium alloys, otherwise known as ‘Inconel.’ The thin film of metal influences the way light is reflected, refracted, and transmitted through the glass. Bell also experimented with changing the temperature and combining metals, all while monitoring the chamber through a window to assess the changes. Rachel noted that Bell, the only artist alive of the three discussed, is actively involved in the conservation of his work, providing conservators with replacement panels when they break.

The above represents but a small portion of the project embarked upon by the GCI (Getty Conservation Institute), a study of the materials and working methods of these and other artists active in the LA area during the postwar period who borrowed from modern industry. The study is a part of both the Pacific Standard Time initiative that included a recent set of exhibitions across Southern California sponsored in part by the The Getty. It also represents the GCI Modern and Contemporary Art research initiative. Future plans include a publication to disseminate the work, a short video, and an exploration of practical applications for the information gained, such as ways to mend cracked and chipped polyester and acrylic resin. Ultimately, the research of Rachel and her colleagues, Emma Richardson and Tom Learner, will hopefully help facilitate treatment decision-making for conservators working with modern and contemporary artwork.

40th Annual Meeting, Wooden Artifacts Session, May 11 “The Establishment of Collaborative Platforms in Protecting and Conserving of the Global Cultural Heritage”, Dr. Hany Hanna

Dr. Hany Hanna, who is the General Director of Conservation for the Helwan, El-Saf and Afteh Sectors of the Supreme Council of Antiquities in Egypt, delivered a general call for increased levels of attention on a local, national, regional and global scale to the protection and conservation of global heritage. While his talk did not relate to wooden artifacts specifically in any way, it was directly related to the theme of the Annual Meeting as a whole, and since Dr. Hanna specializes in the conservation of wooden objects and has spoken to our group in the past, no doubt he felt WAG was the appropriate venue for his talk this year.

Dr. Hanna began by defining cultural heritage as including both the tangible and intangible. Tangible heritage includes:

  1. Cultural
  2. Natural
  3. Cultural Landscapes
Intangible heritage includes:
  1. Practical experience
  2. Knowledge
  3. Skills
He pointed out that cultural heritage is priceless for humanity as a whole, as well as for nations and groups. It both strengthens identity within groups, as well as respect for and appreciation of other groups. Dr. Hanna discussed the fact that while great strides have been made on a global scale in protecting our global cultural heritage through education, advances in technology, and the development of new facilities and international partnerships, more must be done to protect cultural heritage form man-made and natural threats. In general, he called for more training, more investment in research and education, as well as facilities to carry out this research and training, and more international cooperation and partnerships.
At the same time, Dr. Hanna encouraged self reliance on the part of governments, NGO’s and universities in individual countries. His point seemed to be that while networking, cooperation and partnerships are vital for the preservation of global cultural heritage, local action and raising local public awareness are the most effective means of achieving preservation goals of emergency preparedness and recovery, risk and damage assessment, and reconstruction and restoration.
In general the ideas and approaches outlined by Dr. Hanna are completely in accord with the thinking of the US conservation community. But it was encouraging to hear them being expressed by a colleague from Egypt. Dr Hanna made two points which were somewhat more surprising. He called for what amounts to an international certification program, validated by local governments but defined by professional organizations, which would include measures to protect against malpractice. I for one had not heard this idea suggested before, and I’m not sure US conservators are ready to embrace such an idea, given our recent decision on a US certification program. But it may reflect the different experience of Dr Hanna in the practice of responsible conservation.
Dr. Hanna also called for the integration of cultural heritage and conservation issues with other economic sectors, suggesting that this would aid social and economic development. This seems to me to be essentially the same argument the Anne-Imelda Radice made in her address to the general session. But in discussing this, Dr. Hanna suggested that conservation training needed to be based “on every day life on a wider level”.  By this I took him to mean that conservation training needs to be related to and made relevant in the lives of the people living with the cultural heritage the training program is intended to protect. This seems an eminently sensible suggestion, and relates Dr. Hanna’s talk to the next talk in the WAG session by Ton Wilmering, discussing the World Monuments Fund’s new conservation training program in the Forbidden City in Beijing China, which I will discuss in my next blog.

AIC’s 40th Annual Meeting, Research and Technical Studies Session, May 10, “Digital imaging analysis of writing materials using Photoshop Assisted Spectroscopy”, by Kristi Davenport, Holly Herro, Peter Gabriele

NB: Before I try to blog about this talk, I need to say that…well, we didn’t really ever get to discussing Photoshop Assisted spectroscopy! Meaning, this blog will contain some interesting tidbits but you won’t be learning much about this technique or how you might use it in your lab/institution. Sorry!

The project highlighted in this talk was the analysis of the logbooks and writings of Dr. Nirenberg, a Nobel Laureate. Dr. Nirenberg cracked the genetic code (our DNA) and his writings are considered a national treasure. The bad news is that all of his writings were made using ballpoint ink and ballpoint inks are notoriously fugitive. This project used the Photoshop Assisted spectroscopy (is this just kind of like hyperspectral imaging???), and interviews with Dr. Nirenberg’s former technicians to figure out what different markings mean in the logbooks and writings (eg, there are occasionally red marks in the books which were used by Dr. Nirenberg to indicate points/data/results of interest). Also, drops/stains on the charts/files turned out to be because solvent was accidentally dropped onto the books during lab experiments.

http://en.wikipedia.org/wiki/Marshall_Warren_Nirenberg

INKS
* First ballpoint pen was patented in 1818; the pens were used to mark leather
* The inks contained within are not very archival and weren’t designed to be
* Ball ink is used by some artists and it will fade with time
* There are a lot of components in ink; dyes and pigments; solvents, resins, emulsifying agents, lubricants, viscosity modifiers; optical additives; anti-corrosives;
* The rolling ball at the tip of a ballpoint pen is supposed to plow through the ink, pushing it onto/into the paper. You can get buildup of ink at the front of the pen if the pen doesn’t work well and results in those goopy clumps you sometimes get;
*As soon as the ink comes out from the interior, the ink is oxidizing
*The roller ball can pick up residue from the surface of the paper and roll it back into the ink reservoir – this is not good because you can get a build up of garbage interacting with the ink.
*All new inks that are out there have fluorescing agents in them – to make ink look brighter with the artificial lighting used in most office spaces – this is a way you can differentiate modern inks from older ones when examining documents
* ballpoint ink pens is a $20 Billion/year business; the entire idea is for you to keep buying these products
* Before 1949 – inks in pens were oil based; these inks are very stable and you can use this information to help you differentiate when inks were applied to a substrate
* black ink is black because it has all the chromophores in it; when it degrades/separates, it changes color; other colors fade
* All inks have different fingerprints

When you get a historic document, you don’t know starting point of original ink. But you can look at the current state of the ink and you can start to understand degradation process.

SCANNING DOCUMENTS
A scanner is actually a spectrometer. Every pixel has an RGB value, but the computer mixes the colors for your eye. However, you can use those same values in a more creative way: If you consider the RGB values as values for a three dimensional space, you can use the values to plot them on a 3D map and track different types of inks used on historic documents.

AIC’s 40th Annual Meeting – RATS morning session, May 10, “Atomic Layer Deposition (ALD) films as protective coatings for silver”, by Amy Marquardt, Glenn Gates, Eric Breitung, Richard Ash, Gary Robloff, Ray Phaneuf, and Terry Drayman-Weisser*

*nb: the title of this talk, the author list, and author order all changed from what was published in the program. If I have left out an author name, I apologize.

The focus of this talk was to discuss the application of atomic layer deposited films of aluminum oxide (Al2O3) onto sterling silver surfaces. Ultimately, it is hoped that this process will be refined for use with sterling silver art objects in museums.

The overarching goals of this project are to find a coating for silver that is long lived; slows the diffusion of sulfur to the surface of the art object (I learned this fact at the presentation by Zeev Rosenzweig at the RATS luncheon); can be rapidly applied and covers the object homogeneously; is removable; and is less labor intensive than manual application and mechanical polishing.

(wow, that’s a lot!)

The University of Maryland has a “BENEQ TFS 500”, a commercially available atomic layer deposition (ALD) machine/instrument, to deposit thin film coatings on anything that is placed inside of it.
http://www.beneq.com/tfs-500.html

Awesome facts of this instrument:
• Samples placed in the instrument can touch one another and it won’t affect deposition;
• You can coat MANY samples all at the same time
• You can control the thickness of the layer you deposit onto the objects you place inside the instrument, down to the nanometer (nm) thicknesses
• Coatings are incredibly uniform
• The films made are dense (ie, tightly compacted), and these types of films make good vapor barriers
• Coating will go into very small crevices and tool marks
• Tailoring thickness allows you to control optical properties
• It can take a mere 1 hour to make a coating that is 100 nm thick

The project is currently examining whether aluminum oxide coatings perform better than nitrocellulose ones. They used accelerated aging studies (40°C, 30-50% RH, 20 ppm hydrogen sulfide pumped through a sealed chamber) on coated samples and performed Tarnish Rate Analysis (never heard of this!! measure color of tarnish; correlate to thickness of tarnish layer), X-ray photon spectroscopy (XPS), secondary ion mass time of flight mass spectrometry (SIMS-TOF), and atomic force microscopy (AFM) to analyze this.

RESULTS and CONCLUSIONS:
* A 80 nm aluminum oxide coating outperformed a microns thick nitrocellulose coating because it is more tarnish resistant than nitrocellulose.

* They said that that these results are very fresh and new but that the aluminum oxide coatings are removable with a minimal loss of surface copper and silver using dilute sodium hydroxide (NaOH) but that you have to be careful about the concentration of the NaOH because it can selectively remove copper over silver from the sterling silver alloy itself. But that we should all relax because the amount of copper or silver being removed is on the nanoscale.

Q&A session:

Comment: Eric presented removability study with weak NaOH compared to data from Glenn (I don’t know if this work is published or has been presented elsewhere), who used three different chalks (all of which were in the lab);

Q: is this atomic layer deposition instrument expensive?

A reactor costs…$500K. BUT you can build one or buy the parts separate and assemble one yourself; not rocket science to build one; there is a place in Cambridge (MA? England?) that sells on for <$100K; you can make a homemade one for ~$50K

Q7: how long will coating last?

At least 20 years; a guess, no hard evidence

One facet of this project is to build coatings even better than aluminum oxide

TERRY Weissman: lot of the current results presented here are theorhetical; we will be getting into more of the conservation issues as time goes along;

Also, we knew that NaOH would affect the copper; but often times, art objects are already Cu depleted; We might find a better solvent in the future

AIC’s 40th Annual Meeting – RATS morning session, May 10, “Progress in the investigation of silicone rubbers and their residues”, by Kasey L. Hamilton, Adriana Rizzo, and Anna Serotta

The focus of this presentation was to address problems associated with the use of slow and quick setting silicone rubbers for objects conservation applications. The main problem is that silicone rubbers often leave behind liquid and solid residues on objects after they are used. While it may be possible to physically remove the solids, the liquid residues often result in the development of a stain on the surface of the object where the silicone rubber had been applied. The question becomes, what is the chemical make up of these stains and can they be removed using solvents?

Why are we using these silicone polymers in the first place?
• to make casts for recasting
• to allow you to see an image or tool marks inscribed into a object better than you can see them on the object itself (silicone rubbers are homogeneous in color while objects themselves may not be)
• to non-invasively investigate the surface topography of the artifact

The research project entailed selecting eight different silicone rubbers and applying them to a series of different surfaces (plaster discs, limestone, and glass). Following removal of the silicones, attenuated reflectance-fourier transform infrared spectroscopy (ATR-FTIR) was used to determine the chemical make up (O-Si-O and Si-CH3 bonds) and depth of penetration of the liquid residues left behind. Several types of mass spectrometry (evolved gas, pyrolysis gas chromatography [PYGC-MS]) were used to study the eight rubbers and the molecular weights of the materials that are excreted out of the silicone rubbers and left on the different substrates.

RESULTS AND CONCLUSIONS:

* Hexane can be used to remove some of the staining material. I wasn’t sure how this conclusion was drawn? Regardless, it was a better solvent than either methanol (or was it ethanol) for removing some of the residue.

* When residues were observed, the color of residue was related to the color of the mold/silicome material

* Residues are mainly high molecular weight (HMW) components of the silicone rubber and are in their polymeric form – this wasn’t necessarily an expected outcome but it was what was observed

* It wasn’t possible to do a quantitative comparison of the amount of residue left behind between different rubbers

* Slow setting silicone rubber is bad for porous surfaces and residues can penetrate up to 100 microns into the surface (depending on the porosity of the object)

* Given the same rubber, the amount of residue left behind is a function of the material its applied to (intuitive?)

*Siloxane residues are comparable for quick setting rubbers

*Residues maybe reduced, but it is unlikely that they are effectively removed even with non-polar solvents

* There were a couple of others, but future work is to see if barrier coatings (methylcellulose) will help prevent residue deposition.

COMMENTS made following the presentation:

Baltimore museum stopped using silicone rubbers years ago; using silicones on rubbers causes patinas to disappear – patinas were saturated with silicone residues; little bits of set silicone were stuck in interstices of porous surfaces;

• I was surprised – atr is not really ideal for depth of penetration analysis; I also don’t think you can examine an area smaller than 20 um wide; can be hard to measure depths of penetration very accurately)

Any idea how porous the plaster is? Gypsum plaster – can you measure porosity?

Made sure used same batch of plaster throughout the experiments

AIC’s 40th Annual Meeting, The Creation, Implementation, and Safety of Digitally Printed Fabrics in Textile Conservation: Where are We in 2012?, by Miriam Murphy

Author Miriam Murphy, Kress Conservation Fellow, Museum Conservation Institute, and National Museum of African History and Culture, Smithsonian Institution, presented a review of digital printing techniques and their use in textile conservation. This was a great refresher for colleagues who have not kept up with advances over the past decade, including your’s truly.

There are seven steps in producing digitally printed textiles. Step 1 is the digital capture, using scanner or camera. Often this is done by the conservator.

Step 2 is image processing, which is bet left to the printer in order to produce accurate results and avoid hair-tearing-out by the conservator.

Step 3 is color management, for which a color blanket is an essential tool. This is a full printout of colors on the chosen substrate, best compared to the source object in the same lighting as eventual display, ie the gallery or historic house. The small fee for this color blanket is well worth the investment.

Step 4 is the printing process. Although 600-700 dpi is available, 300 is usually plenty good. Printers can print up to 138″ wide and are often constrained only by the size of the image file.

Step 5 is choice of ink. Pigment based inks are the best choice because they require no pretreatment to the substrate and dry with heat. They are susceptible to breakdown in extreme light conditions and with abrasion and much washing. Dark colors can also be hard to achieve and contrast between adjacent dark colors is not always great. Museum conditions usually can accommodate these limitations.

Step 6 is choice of substrate. There are many, many available substrates, but cotton remains the best choice for museum applications. The weave structure of the original does not have to match because the image will provide this detail. Fabrics are available form the printer or from TestFabrics or Jacquard Inkjet Fabric Systems.

Step 7 is pre and post treatment assessment–I confess my notes are sketchy about this step.

If you are interested in speaking with digital print houses, Ms Murphy suggested several including Super Sampler, First2print, LTS Design Service Corp and Digifab, most of which are in NYC, I believe.

The benefits of digitally printed fabrics in museums has been outlined elsewhere, but highlights include quick turnaround, high resolution, and increasingly small dye runs. Why aren’t we all using this technology??!!