The conservation and restoration of panel paintings can be difficult since the object is composed of two media: wood and paint. Unlike conservation and restoration of paintings on canvas, panel paintings are more diverse in terms of problems that lead to conservation and restoration. In the U.S., it is recommended that conservation practices follow the "Code of Ethics" set by the American Institute for Conservation of Historic and Artistic Works.
Video Conservation and restoration of panel paintings
Preventative care
Preventative care is the easiest form of caring for panel paintings. Improper storage conditions, environmental conditions (e.g. light, temperature, and relative humidity), and handling can act as catalysts in damaging effects such as chemical and structural damage to the paint seen through skin oils and degradation through high humidity or high temperature levels. Prolonging the ideal current state of the panel painting can be done through the following accepted methods used:
Handling
Proper handling of panel paintings specifically are similar to that of paintings and other two-dimensional works. Planning the move (including using the proper amount of staff), communication within the handling staff during the move, the use of nitrile or other recommended gloves, the use of painting carts and other proper tools (e.g. using a pallet jack or furniture dolly when moving a panel painting within a crate), handling with two hands or in tandem, etc. are recommended. The Metropolitan Museum of Art, the Canadian Conservation Institute, and the Australian Institute for the Conservation of Cultural Material provide general handbooks that discuss the proper handling and care of paintings.
Storage
Sliding screens or slotted shelves made out of MDF or heat treated wood coated in polyurethane are typical storage units seen in museums. "S" Hooks or other hooks are used to hang objects with the proper hanging hardware (e.g. D-Rings or eye brackets with picture wire) onto the screen. Temporary storage solutions could include the use of ethafoam, moving/packing blankets, and archival corrugated cardboard. In-depth storage details can be seen through the Canadian Conservation Institute's Storage and Display Guidelines of Paintings.
Environmental conditions
Fluctuating humidity and temperatures or improper handling can lead to smaller problems within the structure and painted surface that accumulate. This can be seen in panels that are made up of multiple pieces of wood to make a larger surface area and the damage can be seen towards where the pieces of wood are attached (Current Approaches to the Structural Conservation of Panel Paintings, pg. 318-319). Temperatures should be kept within 5% +/- of 70 degrees Fahrenheit with humidity within +/- 5% of 50% Relative Humidity. Relative Humidity over 65% could lead to mold growth and dry rot. More information can be found through The National Gallery's website, The American Institute's website (including their Wiki Page on Environmental Guidelines).
Exhibition conditions can also fall into this category as the panel painting is subjected to various environmental conditions.As stated, the temperature and relative humidity levels must stay within 50% +/- 5% RH and 70 degrees Fahrenheit. The Canadian Conservation Institute discusses light levels and air pollutants in Environmental and Display Guidelines for Paintings. There must be sufficient air filters attached to the HVAC system to reduce the air pollutants within the air in gallery/exhibition spaces along with storage areas (via reducing gases potentially emitted by various objects). Light levels must be at approximately 50-200 Lux and there is an irreversible light lifetime per panel painting as described by the Canadian Conservation Institute article.
The ELSEC Model 775 Handheld Light Monitor Data Logger is an easy way to monitor the environmental conditions, including light levels, temperature and Humidity.
Integrated pest management
Integrated Pest Management polices are created to reduce or limit any problems relating to pests damaging objects within collections. Various concepts discussed in Integrated Pest Management Policies include restricting food and sugary drink consumption in exhibition and storage areas and surrounding areas along with maintaining cleanliness in exhibition and storage areas. More information about proper Integrated Pest Management policies and examples of pest damage can be found below:
- Smithsonian Institution.
- National Park Service .
- Museum Integrated Pest Management.
- Government of Canada's "Agent of Deterioration: Pests"
- museumpests.net has pages relating to the Prevention, Monitoring, Identification, etc. relating to pests.
Maps Conservation and restoration of panel paintings
Examples of causes of damage
Damage can also come from various sources:
- Improper Relative Humidity
- Low Humidity reduces the chemical changes but raises the risks of mechanical damage to the paint but also makes it more brittle.
- High Humidity reduces mechanical damage but raises the risks of biological organisms, e.g. white efflorescence and green-to-black stains. For more information regarding this concept, refer to the American Society of Microbiology's article
- High Humidity also raises the risks of curving of the wood over time, forcing the paint to flake off.
- Flooding will cause swelling as seen in the case study by the Getty Conservation Institute's Part Four: Current Approaches to the Structural Conservation of Panel Paintings
- Improper Temperature
- For more information regarding damage from environmental conditions, refer to the Northern States Conservation Center's article
Examination
Structural
Proper examination of the object is an initial step in the conservation process. Technologies, such as Radiography and reflectography, are most commonly used. Radiography tends to provide the effective technique in terms of analyzing the condition and preservation work done on the structure of panel paintings. Other uses of radiography can be seen by the opaqueness of specific colors used in the painting, condition of the wood, thickness or density of the wood, and various damage done by pests. Furniture and Larder Beetles can burrow into wood. Illustrations of these beetles can be found through the Insects Limited Incorporated Museum page. Other examples can be found through Museumpests.net's Identification page.
Surface and painting
Photographic documentation and the use of magnification with the naked eye used with diffuse and raking light, common methods used at art museums like the Tate Museum in the United Kingdom, tend to be the most effective tools for initial observation. Causes for damage for the surface of the painting can be caused by the structural issues seen in the wood of the panel paintings (including damage done by wood-boring pests). Damage to the painting can also be caused by temperatures and relative humidity levels that fluctuate, too high, or too low.
Examples of technology
- Reflectance transformation imaging is a type of computational photography that uses digital computation instead of optical processes to create new data as seen with the Penn Museum's Fayum Mummy Portraits.
- X-ray Fluorescence (XRF) "is a non-destructive analytical technique used to determine the elemental composition of materials" (https://www.thermofisher.com/us/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/elemental-analysis-information/xrf-technology.html). More information can be found through: X-ray Fluorescence. An example can be found here with the painting Ophelia in the collection at the Tate Museum.
- Multispectral Imaging
- X-Ray Radiography
- Ultraviolet Light - The example is Ophelia seen in the collection at the Tate Museum
- Infra-red reflectography - Another example using Ophelia seen in the collection at the Tate Museum
Treatments
Structural
Occasionally, pests can cause damage to the wood panels used in panel paintings. The pests must be eradicated prior to conservation to ensure the longevity of the object and the conservation work, which examples of stabilization of panels follow this section. Examples of Treatments include:
- Isolation through bagging - includes the object in isolation with blotter paper, paper board, tissue or foam sealed in a polyethylene bag and monitored over several weeks or months
- Low Temperature - typically putting the object into a freeze qualified for this type of use. Requirements include a freezer that can reach -20 Fahrenheit (-29 degrees Celsius), objects must be put into the freezer inside a resealable plastic bag, and should be in the freezer for 4 hours
- For more information regarding these treatments and for other treatments, use the Museumpests.net Solutions page.
Conservators must adapt to the specific case of each panel and must use their experience to their advantage. Structures used in conservation include:
- Custom strainers that are curved to match the panel with springs to safely flex (as seen in the Tuscan Panel discussed in the Getty's presentation on Hybrid Approach to Structural Treatment of Panel Paintings)
- Cradling - Cradling is the additions of support on the back of the panels. The supports must have some flexibility to allow for some movement from slight temperature and humidity changes as seen in the second example in the Getty's presentation on Hybrid Approach to Structural Treatment of Panel Paintings
- Adhesives - Often, if there is a simple crack within the panel, adhesives are use in combination of alignment, and moderate compression. All adhesives used must adhere to the Code of Ethics described earlier and must be reversible.
Various treatments of adhesives include:
- Reactivation of hide glues
- Adding water-based emulsion glues to existing and failing adhesives
- Replacing failed adhesives, which includes removing all forms of the failed adhesive before replacing the adhesive with a more modern counterpart.
Examples of adhesives are:
- Natural protein adhesives - found through animal products such as casein, albumin, fish glue, and animal-hide glue.
- Natural resins - not as widely used but often seen in historic objects. An example would be Shallac.
- Synthetic resin adhesives - most widely used is "aqueous emulsions of polyvinyl acetate (PVA) and arecommonly called "white" glues"
- More in-depth information regarding adhesives can be found though the Getty Conservation Institute's Article A Survey of Adhesives for Wood Conservation by Donald C. Williams.
- Transfer of Panel Paintings - The transferral of a painting from an often highly unstable panel to another panel is a delicate process. Often there is some form of degradation to the original panel, including pest damage (burrowing), warping, or the thinning of the panel. The transfer should be made to a similarly aged panel that is of the same wood type. The National Gallery in the United Kingdom provides an example with Raphael's Virgin and Child
If the panel is submerged due to flooding, the recommended procedure is to expose the panel painting through a long drying process prior to any further conservation work. Conservation work on one panel painting that has two or more panels comprising the final object should be similar to that seen in the restoration of Florentine Panel Paintings as seen in Part Four: Current Approaches to the Structural Conservation of Panel Painting's Florentine Structural Stabilization Techniques by Andrea Rothe and Giovanni Marussich.
Surface and painting
Conservation of paintings can vary due to the wide range of types of paints and can include cleaning, removal and replacement of degraded varnish to the restoration of paint losses. The Tate Museum described that "Cleaning is a particularly delicate and demanding part of conserving and restoring paintings. Layers of dirt, discoloured varnish and old restorations that may be disfiguring or obscuring parts of the composition are painstakingly removed."
More information on the conservation and restoration of oil, acrylic and fresco paintings can be found throughConservation and Restoration of Paintings. Terminology used in the examination of paintings conservation and some condition reporting terminology can be useful during both the examination and conservation processes.
The Getty Conservation Institute also provides information surrounding their case study on Modern Paints. It addresses the modern paints (e.g. "synthetic binders--most notably acrylic, alkyd, polyvinyl acetate, and nitrocellulose") that could be used in the contemporary versions of panel paintings compared to 15th Century Oil Paints and the continued studies in the evolution of paints.
For assistance with conservation, restorations, and questions regarding an object, the American Institute for Conservation of Historic and Artistic Works can help with finding a conservator to assist with assessments, conservations, and restorations.
Outreach
The Penn Museum, based out of Philadelphia (Pennsylvania), has the Artifact Lab that is attached to the museum where it can interact with visitors. It also provides a great blog and other relevant pages relating to their Artifact Lab and its operations. Both are great assets for outreach and to make the conservation process a little more transparent. It has blog sections discussing anything from general cleaning with photos (with objects under different lights) to using various scanning technologies (such as X-radiography) to observe hidden aspects of the objects. The Lab, much like their museum counterparts, have two sections where the public can either ask questions or have general questions answered: the "Frequently Asked Questions" section and the "Ask Us!" section. The "Currently in the Lab" section includes the objects that are or have been in the Lab for conservation and an object will occasionally have related blog posts attached to it.
The Frequently Asked Questions section relating to the collection but, more importantly, it has a section addressing conservation that includes an answer to the question regarding "How do you become a conservator?"
References
External links
- The Getty Conservation Institute has multiple resources through a YouTube Playlist on Panel Paintings Conservation and the Panel Painting Initiative page on their website
- Victoria and Albert's Conservation Treatment of a 17th Century English Panel Painting
- The Metropolitan Museum of Art's A Treatment for Panel Paintings
- Asian Art Museum's Conservation of a South Asian Painting
Source of article : Wikipedia
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