Caroline Roberts, a graduate fellow at the Winterthur/UDel Program in Art Conservation, was lucky enough to spend a summer working at English Heritage with David Thickett, a pillar in the specialty of preventive conservation. Cary shared her involvement with various projects from her internship. For an overwhelming 400+ properties, Thickett’s work emphasizes practicality, resource-sharing, and sustainability. Decisions for environmental monitoring and analysis are data-driven, and thereby, case-by-case. This sensible method identifies and address problems when and where they occur, rather than applying and managing a systematic approach to many, many sites. Cary highlighted sophisticated and simple technology used, such as radio transmitters for remote data access, as well as iButton loggers in a micro-environment. I was impressed by the fine level of the problems being addressed in EH’s projects: they suggested that the institution has a handle on general preventive conservation management.
Category: Research and Technical Studies
Posts on research, materials & techniques used in and by conservators
AIC’s 39th Annual Meeting – RATS, June 1, “The Development and Application of Active Microclimate Control Devices” by Jerry Shiner, Keepsafe Microclimate Systems
Jerry Shiner’s clear and informative talk adeptly answered the questions: how does that little box work and how did it get here? In other words, everything you ever wanted to know about active microclimate systems (aka microclimate generators, MCGs), but were afraid to ask. Starting from MCGs’ humble beginnings in 1938, Jerry reviewed and illustrated (with his excellent drawings) the technological history and innovations that have lead to the elegant, compact devices available today. I could not help but think of the charming series, The Secret Life of Machines.
Used with a well-sealed case (this is key), a MCG controls all of the factors a good HVAC system can: T, RH, and air exchanges. It can also provide readings, fail safes, and alarms. To boot, they have hip names such as the Mini One and the Maxi 60, available through the speaker’s company. This sensible talk inspired my confidence in these devices, as well as Jerry’s interest and diligence in continuously improving them. He spoke of “magical thinking and microclimate control,” something many AIC attendees may quietly have in common.
AIC RATS – Microclimates – June 1, 2011
AIC RATS – Microclimates
June 1, 2011
Museum environmental guidelines and the implementations of change
Charlie Costain – Conservation and Scientific Services,
Canadian Conservation Institute (CCI)
Follow up to “plus/minus” dilemma we’ve been having otherwise known as: “Should we loosen up the environmental restrictions on museum loans to other institutions?”
At CCI – 2,500 museums support across Canada and 500 archives. They were looking for an approach that can be adapted for a variety of organizations.
Recap of “Plus/Minus Dilemma” at AIC 2010: http://www.iiconservation.org/dialogues/
Highlights:
• Jerry Podany: IIC – heritage conservation in the broader context of the modern world;
• Max Anderson: candor and honesty of what you’re doing and flexibility between parties and technical capacity of the buildings and energy concerns;
• Nancy Bell: in the UK AVISO group ask staff at Tate to reexamine conditions for loans and exhibitions – carbon emission reductions and new funding for research IGOR;
• Karen Stothart: talked about the balance of need of exhibitions and loans and the protection of those 50% RH does shift during winter;
• Cecily Crzywacz: there is no magic bullet for conditions for all institutions;
• Stefan Michalski: he felt that consensus that 10% +/- OK for most collections;
• Terry Weisser: conservators are concerned about energy savings, but need to take care of collections also. Welcomes more research in this area for wider and looser parameters.
ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers)
This is the organization that conservators look to when determining setpoint and HVAC standards for museums. There is an ASHRAE handbook that is put out every three years that includes information about designing museums . However, the temperature and RH setpoints/ standards have not changed since 1999! This handbook is written in engineer language; design parameters; system selection for engineers. ASHRAE proposes classes of control: AA, A1, A2, B, C, and D. Cool, cold, and dry are the best conditions (duh) and each class has its collection risks and benefits. See list below:
Class of control / Relative Humidity / Temperature
AA: 50% RH +/- 5% 75°F (high) 55°F (low) +/-4°F
A1: 50% RH +/- 10% 75°F (high) 50°F (low) +/-4°F
A2: 60% RH in summer and 40% RH in winter +/- 5% 75°F (high) 50°F (low) +/-4°F
B: 60% RH in summer and 40% RH in winter +/- 10% 75 +/- 5 and cold +/-5
C: 50% RH +/- 25% Below 85°F
D: Below 75% RH Below 85°F
ASHRAE also has building types; higher Roman numerals have more climate control
Climate control: (VI) collection vaults, (V) museums
Partial control: (IV) and (III)
Uncontrolled: (II) and (I)
Why ASHRAE?
• Consistent with risk approach to making decisions on collections
• Flexibility for difference types of collections and locations and building types
• Facilities communication between engineers and collections folks
Example: Risk assessment on historic house in Ontario
First questions during the assessment: collections and relative value of collections; created collections “pie” chart; building vs. collection; and collections overall by percentages.
They decided the building was the most important asset, but spalling was occurring because they were trying to maintain 45% RH inside; reduce RH will reduce strain on building envelope.
There is some confusion about RH and temperature. There is a perception that RH is an issue of paramount importance which can lead to inappropriate RH as in the above example.
• Lack of awareness of options
• Lack of transparency in operations, loans and grant requirements
• As a result, discussions have begun on the federal level in Canada
“Saving Money, Preserving Collections” dialogue
• Overview of evolution of guidelines for museum environment
• Operation of facilities – facilities managers
• Current operations – shared opportunity for savings
• Conditions for loans/ funding
What temperature and relative humidity can we have to satisfy loan and grants?
Operating Conditions in National Museums
o Differs depending on type of building and collections
o Purpose building facilities run at 50% RH +/-5% in the summer and 43% RH +/- 5% in the winter, with a temperature at 21°C
Agreement on the following from museums across Canada:
• When sending materials to another Canadian museum, the loaning museums will not demand better conditions than their own
• Museums will lend objects containing hygroscopic materials to institutions that can achieve Class A conditions
• Federal grant class A will be requirement where applicable
• This is not a strait jacket – meant to be a starting point – obligation as to why this object is not suitable – more candor and information exchange
• Having the discussion and getting agreement from some of these major players is a starting point
o Moving from a rules based approach to a risk based approach – there is work to be done in terms of communication and research
Any suggestions? CCI would appreciate your input – drop him a line! Charlie.costain@pch.gc.ca 613-998-3721
The Off-Grid Museum
National Museum in Denmark
Dr. Poul Larsen and Tim Padfield
Energy savings – Denmark has been doing it WAY before it was cool and hip. Tim has worked with saving energy in conservation for many years. The presentation was given by Dr. Larsen from the National Museum in Denmark.
He showed us buildings that are relevant to the subject: energy savings
As you know, buildings depend on external energy sources to function – light, temp, RH, etc. Museums are big time energy consumers and Denmark is trying to create a building that doesn’t rely on external energy sources and uses only renewable energy sources, taking into account climatic exceptions.
One example that he gave was this Nydam Iron Age warship that was exhibited in a temporary shelter designed as a balloon. As you can imagine, energy use quite large because sealing a balloon is no small feat. Needless to say, the “balloon” leaked, causing an unstable climate – maybe C or D class in ASHRAE terms. Air conditioning depends heavily on the building envelope and the envelope was failing in this example. TO add some more fun to the mix, there was a 6 hour power outage and the balloon collapsed – only held up by wires. Constant energy supply may become a luxury and not a constant.
He showed us another warship that was transformed into an exhibition building – a submarine-turned-museum. The interior of the submarine had a kitchen, bath, and “artwork” aka pinup girlie pictures. Hilarious!! This space has a very unstable climate – doesn’t even class in ASHRAE system.
Example: A museum building with thick concrete walls located in the open landscape from the 1930s. Truly off grid – not even a telephone line and all one level. Museum has only natural lighting – insulation – high ceiling for human health requirement. Natural ventilation sufficient for air quality, no temperature and RH control. In winter we need heat for humans – ground heat pump is the most energy efficient way to heat.
Example: Gallery for minerals display that has a ground heat pump for winter heating and underfloor heating. It uses 4-5 kilowatt hour for heat. Wind energy index can be used as an energy source – a lot of wind in winter and coexists well with heat pump that could be powered by wind energy if necessary. The gallery has a heavy structure to give thermal stability and thermal insulation to reduce heat loss. Small windows reduce solar heating but allow for natural lighting. No humidity control but passive humidification from the walls but not intended – buttresses are taking in the rain water. Efflorescence is occurring on the walls, but it is not as dry in winter so it actually helps.
Example: 17th century house in Liselund Park. This house is only open to public in the summer and not heated with interior impermeable surfaces and finishes. Dehumidified air is injected to each room through small ducts in the floor to keep RH down. It works quite well according to environmental data. However, the temperature is not steady. Dehumidifier keeps the RH to about 60% – but the dehumidifier is totally keeping it in check – if it fails you’re in trouble. Humidity-sensitive objects should be in microclimates because mechanical systems cannot be relied upon. Energy consumption for dehumidification is constant over the year – could use water turbine to power the dehumidification in summer, which would be a good off-grid solution. Mechanicals are unpredictable, but water freezes so what about winter?
Example: Runic stones in Jelling from 950-970 BC outside – no energy use at all (ha ha ha). Polychrome paintings that were on the stones are lost however – copies are displayed in museum nearby – photovoltaic panels integrated into skylights to give natural and artificial light – solar energy better in summer than winter, but condition stability problem during the seasons. Combine solar and wind energy then it will meet required energy needs for museum.
Read more at www.conservationphysics.org
Some of the questions/ comments:
Isn’t there a substantial cost to building thick walls? They anticipate that the buildings will last many years so that the cost of building will be gained back due to that.
One should note the practical limitations in USA with this type of off-grid environmental controls. Denmark is in Zone 5 maritime – mild climate; the USA varies from Zone 1 Humid to Zone 7 Dry maritime and humid – Zone 5 is very small geographically. One should design a museum to the specific location and its limitations in terms of environment.
New Technologies for Energy Storage Applied to Cultural
Heritage Buildings: The Microclimatic Monitoring of Santa Croce
Museum in Florence
Consiglio Nazionale delle Ricerche,
Istituto di Scienze dell’Atmosfera e del Clima CNR-ISAC
Francesca Becherini
I will admit that I had a difficult time following this talk, so I apologize in advance for the lack of information here. The main idea of this talk was to demonstrate a method of conserving heat (as energy) in Santa Croce, Florence by using a special kind of material in drywall. Storing and then release energy is the concept. I’m thankful I understood that!
Well… here goes nothing…
The folks at the Consiglio Nazionale want to develop, evaluate, and demonstrate an affordable multisource energy thermal and electronic storage system integrated in building based on new materials, technologies, and control system: http://www.messib.eu/
So they installed this system in two civil buildings: S Croce Museum was one of them. S Croce has heating system radiators, but no air conditioning. Illumination is halogen and metal halide lamps.
As I understood it, the materials that will hold the energy or heat are phase change materials (PCM) which has the capacity to stores much more heat per unit volume. It also has a desirable melting temperature in the desired temperature operation range, a high specific heat, small volume change with high thermal conductivity. This material (which I never actually got the name of – maybe they never said it because it’s proprietary?) is available as a paraffin or hydrated salts and used in heating panels and solar (as in sun) systems. There is not much information on the long-term durability of this material nor is it inexpensive. PCM embedded in gypsum plasterboards PCM distributed in 20 with respect to gypsum.
So measurements of this material were made with automatic and manual air, temperature, relative humidity, and surface temperature contact on the surface of the art (I think) as it hung on the wall where the PCM material was infused in the gypsum wall. They chose rooms based on how much art was displayed in the room. Main results are below (as best as I caught them):
Installed panels with monitors for air temperature, RH, temperature of panel, and contact panel of wood board to simulate canvas painting. They also monitored VOCs in museum and lab. Found aromatic chlorinated alcohol terpene compounds, aldehydes, and organic acids. PCM emits low VOCs, but it is strongly reduced when in gypsum panel. Can’t tell about aldehydes and organic acids – formic acid is from gypsum panel perhaps? Not PCM? There were lots of graphs about the PCM effects in the lab. Honestly the explanations aren’t totally clear – something about the melting point of PCM? Maybe?
Anyway, according to all of the testing and graphing, they need more information on the material’s thermal behavior, VOCs emissions, and interactions of VOCs and artifacts.
AIC’s 39th Annual Meeting – Joint Paintings/Research and Technical Studies Session, June 3, “Developing Cleaning Systems for Water Sensitive Paints by Adjusting pH and Conductivity” by Tiarna Doherty
As a fitting end to a conference full of great talks, Tiarna Doherty, from the J. Paul Getty Museum, wrapped up the final session of the joint PSG/RATS session at the annual meeting on Friday evening with an incredible talk about new developments in cleaning water-sensitive paintings. The project was a collaboration between herself and two others, Chris Stavroudis, conservator in private practice, and Jennifer Hickey, Graduate Intern at the Metropolitan Museum of Art, that aims to develop a methodological approach to cleaning water sensitive works by measuring the pH and conductivity levels of the surface of the artwork and cleaning solutions in use.
Doherty began her presentation by introducing us to the Modular Cleaning Program (MCP), a database system that has been developed to assist conservators in their approach to cleaning artworks. The MCP performs valuable computations which assist the conservator in creating cleaning solutions that take into consideration, pH, ionic strength, HLB, and the functions of surfactants, buffers, and chelating agents, within aqueous cleaning solutions. Using MCP workshops given by herself and Stavroudis as an example, Doherty highlighted how practical experience with the MCP has helped them to understand how paints interact with cleaning systems, and thus aided in their current research.
She continued by concisely explaining why they focused on pH and conductivity. First, recognizing that the pH of something as simple as water may vary widely, Doherty notes that even exposing de-ionized to air over a long period of time eventually causes the pH to lower. Likewise, carbonated water also has a low pH, but since an acrylic paint film swells at a pH of 7 and higher, the use of carbonated water has been shown to successfully clean some water sensitive acrylic artworks. Doherty finished her introduction on pH with a brief explanation of buffers and the use of acetic acid and ammonium hydroxide to adjust the pH of water for cleaning, noting that both of these components of the solution will evaporate over time without leaving a residue on the surface of the artwork.
Next, Doherty continued her talk by segueing into an introduction on conductivity. Conductivity, the ability of a solution to transfer (conduct) electric current, was recently explored as a means to evaluate the surface of an artwork during cleaning and to create/develop useful cleaning systems. In a simple manner, the conductivity of a painting’s surface can be measured by placing a small drop of water on the surface of the painting, and then transferring it to a conductivity meter after a short period of time. Doherty reported that recent research in the field has concluded that there is less swelling of a water sensitive paint surface when it is cleaned with a solution that has a of pH of 6 or lower and a conductivity of 6000 micro-Siemens.
The talk continued with two in-depth cleaning case studies on an oil painting and an acrylic painting, which were both painted in the 1960’s, and had proven to be sensitive to water. Using solutions with adjusted pH, various conductivity levels, and the addition of materials such as chelators, surfactants, and even an emulsion system containing a proprietary material called Velvasil®, Doherty’s team tested and successfully developed systems for cleaning each of the two artworks (which, to ensure accuracy of content, I will point you in the direction of the post-prints for the details of).
As Doherty concluded her talk, I couldn’t help but be a little excited about possible implications of this and future research on these topics. This talk not only raised many interesting considerations about the cleaning of paintings, but, it also revealed the practical application of a new a tool set for conservators who face the challenge of water-sensitive paintings.
Bravo Tiarna (and team), I look forward to hearing more as this project progresses.
39th Annual Meeting – Joint Paintings/Research and Technical Studies Session, June 3, “Potential Cleaning Applications of Poly(vinyl alcohol-co-acetate)/Borate gels on Painted Surfaces” by Lora Angelova & Kristin deGhetaldi
Where to begin? First let me start by saying, if you missed this presentation during the joint PSG/RATS session, then you should be sure to check out the paper in post-prints once available. The details and future potential of this research cannot likely be given its due justice in a short blog post, but I will do my best to give you the major highlights.
On the final day of the annual conference Lora Angelova and Kristin deGhetaldi presented their findings regarding recent research on Borate gels, a new aqueous co-solvent gel system for use on painted materials. This collaborative project between Angelova, a Ph.D candidate in the department of chemistry department at Georgetown University and deGhetaldi, the Andrew W. Mellon Painting Conservation Fellow at the National Gallery of Art, along with Senior Conservation Scientist Dr. Barbara Berrie and Professor of Chemistry Richard Weiss at the NGA and Georgetown, respectively, resulted in the development of a new aqueous based gel system with great potential for use by conservators in the cleaning of paintings and painted surfaces.
The presentation was first introduced by Kristin deGhetadi, who immediately hooked the audience with the highly successful results of a case study, which utilized the cleaning gels in question.
The case study involved the cleaning of a painting titled Multiple Views, a 1918 work by Stuart Davis in the collection of the National Gallery of Art. After a brief history of the work, including an antidotal account about how Davis painted the work during a three-day contest in an “atmosphere of drinking and conviviality”, deGhetaldi described in detail the before treatment condition of the work. The painting, which suffered from extensive previous restoration, was waxed lined and covered with an extremely yellowed and degraded dammar coating that analysis revealed contained not only wax, which likely migrated to the surface from the lining, but protein, polysaacharides, drying oil, and, even nicotine.
Needless to say, deGhetaldi realized that this particular coating would prove to be challenging to remove. She described her methodical approach to the treatment using the Modular Cleaning Program developed by Chris Stavroudis. After exhausting the options of traditional free solvents, various aqueous cleaning solutions, and solvent based gels, she turned to the use of an aqueous emulsion that contained Pemulen TR-2 with 5% Benzyl Alcohol. While the latter worked very well to remove the coating over much of the painting there were still areas where a particularly tenacious dark coating remained. For these local areas the Borate gels being developed by Lora Angelova were tested and used for treatment.
Working together, Angelova and deGhetaldi performed a variety of tests with the gels and adapted them to the particular problem of cleaning Multiple Views.
deGhetaldi finished her portion of the presentation describing this treatment with numerous beautiful before, during, and after treatment images and a full description of the practical use of the Borate gels, before handing the podium over to her co-presenter.
Lora Angelova began her half of the presentation by describing in detail the formation, characterization, and modulation properties of the borate gels (and the chemistry involved).
The gels are composed of a partially hydrolyzed poly-(vinyl alchohol-co-acetate) polymer that combines by cross-linking with a very small amount of borate ions. The formation of the gel is immediate and proved to be thermally stable with soft elastic properties found desirable for use in treatment. Additionally, due to the acetate groups present on the polymer, the gels allow for the use of large amounts of polar organic solvents to be incorporated into the system. Which was utilized in the case study discussed by deGhetaldi.
Angelova continued by describing several properties of the gels that may make them useful in conservation, including the fact that the gels are transparent, pliable, and as mentioned, have the ability to hold large amounts of commonly used solvents. She then went on to describe how the gels are easy to remove, leave no detectable residue, and have the ability to clean a precise area with little solvent penetration into the paint layers. Which of course grabbed the attention of the conservators in the audience.
Using the results of from a number cleaning tests and further analysis, Angelova further described testing of the prior mentioned traits. She used residue tests conducted by attaching a naturally fluorescing molecule to the polymer in the gel. This allowed for testing regarding the removability of the gel and demonstrated that no detectable residue of the gel was left behind after removal.
Finally, Angelova eloquently concluded her presentation with a brief discussion of future work and the testing that is necessary in order to fully understand and develop the use of Borate gels in conservation.
So, while these gels may not be quite ready for use in the wider world of conservation yet, as was made clear by both the author’s conclusions and some of the thought provoking questions posed by audience members, they are definitely showing great potential as a tool for conservators already and I know many, myself included, who look forward to hearing more about the results that this project produces.
AIC’s 39th Annual Meeting- Architecture/Research and Technical Studies Joint Session, June 3, Protecting Marble from Corrosion by Sonia Naidu and George W. Scherer
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.
AIC’s 39th Annual Meeting- Architecture/Research and Technical Studies Joint Session, The Basics of Recirculating Fountain Maintenance by Robert Krueger
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.
AIC’s 39th Annual Meeting – Architecture/Research and Technical Studies Joint Session, June 3, Biodiversity and Control Methods of Phototrophic Colonization on Artistic Fountains, Oana A. Cuzman and Piero Tiano
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.
AIC’s 39th Annual Meeting – Research and Technical Studies Session, June 1, “The Macro, Micro, And Economics of Climate Control” by Dr. Fenella France, Library of Congress
Dr. Fenella France, Preservation Research Scientist at the Library of Congress, brought her expertise in preventive conservation to the topic of microclimates in cultural institutions, starting with the what, why, and where’s of microclimates, and ending with a presentation of an über-microclimate display and storage case: the “MOAC” (Mother of All Cases) for the iconic Waldseemüller map. Key points included:
- A microclimate is a environment maintained in a small space that differs from its external environment. This might be at various levels of control within a building: the building itself, a room, a case, a box.
- It is important to create specs for a microclimate based on an understanding of an object’s materials, history, and mechanisms of damage.
- A specific object’s materials and cultural significance may dictate its need for a microclimate.
- Issues which must be considered in planning a microclimate include the composition of the encasement, object access, environmental controls (active vs. passive), monitoring.
The Waldeseemüller map exemplified an object of highest cultural importance and value, which warranted an optimal microclimate for storage and display. Its fantastic encasement provided an anoxic environment, visibility of the object in storage and display, minimized handling, minimized oxidative and hydrolytic degradation, and access for monitoring of pressure, RH, T, and oxygen. A few amazing stats about the case:
- It was designed to maintain a 20-30-year seal.
- It is a 2200 lb case within another case.
- 92 bolts hold the tooled aluminum case together.
- It has maintained 0-30ppb oxygen.
- It has a flexible back to allow for changes in barometric pressure.
The encasement was an impressive, collaborative effort by conservators, engineers, architects, curators, and others. Although an estimated cost for the case was disappointingly not reported, I was impressed by the long-term planning that went into its design, as much as the elaborate, continuing monitoring and analysis conducted by the stewards of this object. Since the completion of the encasement in 2007, the durable case has proven to be effective and durable, as demonstrated by data generated by its monitoring systems. While I was duly wowed by the Waldeseemüller encasement, I would argue that France’s presentation of it as a “case study” was a little misleading. It was an exceptional feat of engineering and effort for an exceptional object. I was hoping for more discussion of more typical microclimate needs and solutions, probably covered in the Microclimate Workshop…
New Sensor Network Protecting Art in NY Museum
- In this photo provided by the Metropolitan Museum of Art, Paolo Dionisi Vici, associate research scientist in the Department of Scientific Research at The Metropolitan Museum of Art, left, and Hendrik Hamann, Research Manager at IBM, discuss a new environmental sensor system that will be deployed at the Clositers Museum in New York, Tuesday, June 7, 2011. Hamann holds an example of one of the sensors that will monitor the climate in the museum and help preserve its walls. (AP Photo/Metropolitan Museum of Art)
NEW YORK (AP)The Metropolitan Museum of Art is announcing Thursday that a network of wireless environmental sensors designed to prevent damage to the collection is being tested at its Cloisters branch.
Read more about the new monitoring program and the need for climate control for the collections in the June 8, 2011 Associate Press story by Jim Fitzgerald on the AP website.