Conservation and restoration of panel paintings

The conservation and restoration of panel paintings can be difficult since the object is composed of two media: wood and paintings. 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.[1]

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 room, Heritage Conservation Centre, Singapore

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.[2] 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

CSIRO ScienceImage 1140 Damage Done by a Furniture Beetle

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:

Examples of causes of damage

Computer rendered illustration of different types of wood warping

Damage can also come from various sources:

Examination

Structural

CSIRO ScienceImage 1831 Borer damaged wood
CSIRO ScienceImage 1831 Borer damaged wood

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.[4][5] 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.

Indianapolis Museum of Art Conservation Scientist using a Micro-X-ray fluorescence machine

Examples of technology

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:

Cradled panel painting, Aert van der Neer

Conservators must adapt to the specific case of each panel and must use their experience to their advantage. Structures used in conservation include:

Various treatments of adhesives include:

Examples of adhesives are:[7]

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

The Scientists by Rita Greer, 2007

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."[9]

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"[10]) 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

  1. ↑ "Code of Ethics and Guidelines for Practice". www.conservation-us.org. Retrieved 5 April 2017.
  2. ↑ "Paintings and their Environment". The National Gallery.
  3. ↑ Alten, Helen (Fall 1999). "Temperature and Relative Humidity". Northern States Conservation Center.
  4. ↑ Murray, Alison (1996). "Air-Coupled Ultrasonic System: A New Technology For Detecting Flaws In Paintings On Wooden Panels". Journal of the American Institute for Conservation.
  5. ↑ "Current Approaches to the Structural Conservation of Panel Paintings" (PDF). The Getty Conservation Institute. October 29, 1998.
  6. ↑ "XRF (X-ray Fluorescence)".
  7. 1 2 Williams, Donald C. (April 1995). "A Survey of Adhesives for Wood Conservation" (PDF).
  8. ↑ Pages 79-86 in Donald C. Williams' Getty Conservation Institute's Article A Survey of Adhesives for Wood Conservation
  9. ↑ "Conservation – paintings". The Tate Museum.
  10. ↑ "Modern Paints". The Getty Conservation Institute.
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