The Care and Conservation of Oil Paintings

Claude Monet
b. 1840 d. 1926 France
The Sunflowers

Throughout the years I have been asked many questions on the care and handling of oil paintings. I have included two comprehensive sources for your reference on the subject. The American Institute for Conservation of Historic and Artistic Works (ACI) article "Caring for Your Paintings" and The Henry Ford, Chief Conservatory Paintings, Mary Fahey. Other valuable resources, and references on the subject of oil paintings, are also listed. If you have questions in regard to the care and handling of oil paintings, I am at your service to answer your questions.

~ Art Diva of PaintingsToGo.com

CARING FOR YOUR PAINTINGS

Paintings may be objects of great beauty or of historical importance, providing an important cultural link with the past. They may have great monetary value or have sentimental value to their owners. Whatever the case, paintings are fragile creations that require special care to assure their continued preservation.Paintings consist of various layers. The paint is applied to a support, typically canvas or wood, which is first primed with a glue-sizing and/or ground layer. Traditional paintings are finished with a coat of varnish. Contemporary paintings, naive, or folk art may not have a ground layer or varnish coating. Paintings that do not have all of the traditional layers may be more fragile and susceptible to change or damage. The paint layers can be made of pigments in oil, acrylic (or other synthetics), encaustic (wax), tempera (egg), distemper (glue), casein (milk), gouache (plant gum), or a mixture of media. The paint can be applied on a wide variety of supports. Although the most common are canvas and wood, other supports include paper, cardboard, pressed board, artist's board, copper, ivory, glass, plaster, and stone. Paintings on canvas are usually stretched over an auxiliary wood support. An adjustable support is called a stretcher; a support with fixed corners is called a strainer.

Paintings change over time. Some inevitable results of aging, such as increased transparency of oil paint or the appearance of certain types of cracks, do not threaten the stability of a painting and may not always be considered damage. One of the most common signs of age is a darkened or yellowed surface caused by accumulated grime or discolored varnish. When a varnish becomes so discolored that it obscures the artist's intended colors and the balance of lights and darks, it usually can be removed by a conservator, but some evidence of aging is to be expected and should be accepted. However, when structural damages occur in a painting such as tears, flaking paint, cracks with lifting edges, or mold, consult a conservator to decide on a future course of treatment for your painting.

MAINTAINING A SUITABLE ENVIRONMENT

It is important to maintain a proper environment for your paintings. The structural components of a painting expand and contract in different ways as the surrounding temperature and humidity fluctuate. For example, the flexible canvas may become slack or taut in a changing environment, while the more brittle paint may crack, curl, or loosen its attachment to the underlying layers. If a painting could be maintained in an optimum environment, in one location at a constant temperature and humidity level, many of the problems requiring the services of a paintings conservator could be prevented. Paintings generally do well in environmental conditions that are comfortable for people, with relative humidity levels between 40 and 60 percent. Environmental guidelines have been developed for different types of materials. Paintings on canvas may react more quickly to rising and falling humidity levels than paintings on wood panels, but the dimensional changes that can occur in a wood panel can cause more structural damage. Owners of panel paintings should be particularly conscientious about avoiding unusually low or high relative humidity and temperatures to prevent warping, splitting, or breaking of the wood. Museums strive to maintain constant temperature and humidity levels for works of art, but even with expensive environmental control systems this task can be difficult. In most cases, gradual seasonal changes and small fluctuations are less harmful than large environmental fluctuations. Avoiding large fluctuations is very important. For example, a painting stored in what would generally be considered poor conditions (such as a cold, damp castle in England) may remain structurally secure for centuries, but begin to deteriorate rapidly if moved into "stable" museum conditions simply because of the extreme change in its environment.

One of the simplest and most important preservation steps you can take is have protective backing board attached to paintings. A Fome-Cor (or archival cardboard backing) screwed to the reverse of a painting will slow environmental exchange through a canvas, keep out dust and foreign objects, and protect against damage during handling. Be sure that the backing board covers the entire back of the picture; do not leave air vent holes, which can cause localized environmental conditions and lead to cracks in paint. The backing board should be attached to the reverse of the stretcher or strainer, not to the frame. Have a conservator or reputable framer attach it for you.

DISPLAYING PAINTINGS

The display of paintings requires careful consideration. Direct sunlight can cause fading of certain pigments, increased yellowing of varnish, and excessive heat on the painting surface. It is best to exhibit paintings on dividing walls within a building rather than on perimeter walls where temperature fluctuations will be greater and condensation can occur. If paintings are placed on uninsulated exterior walls, it may help to place small rubber spacers on the back of the frame to increase air circulation.

Although a fireplace is often a focal spot for a room, a painting displayed above a mantel will be exposed to soot, heat, and environmental extremes. Hanging paintings above heating and air conditioning vents or in bathrooms with tubs or showers is also inadvisable because the rapid environmental fluctuations will be harmful. Select a safe place away from high traffic and seating areas.

When lighting paintings, use indirect lighting. Lights that attach to the top of the frame and hang over the picture can be dangerous. These lights cast a harsh glare, illuminate and heat the painting unevenly, and can fall into the artwork causing burns or tears. Indirect sunlight, recessed lighting, or ceiling-mounted spotlights are best for home installations. Halogen lamps are increasingly popular, but halogen bulbs emit high levels of ultraviolet light (the part of the spectrum that is damaging to artworks) and should be fitted with an ultraviolet filter when used near light-sensitive materials. These bulbs also have been known to explode and may pose a fire hazard. Tungsten lamps may be preferable for home lighting.

HANDLING PROCEDURES

Pictures are usually safest when hanging on a wall, provided that they are well framed, with the picture and hanging hardware adequately secured. If you must store a painting, avoid damp basements or garages, where pictures can mold, and attics, which are very hot in the summer. A good storage method is to place the paintings in a closet with a stiff board protecting the image side of each artwork and a backing board attached to the reverse. Here again, a backing board attached to the reverse can protect your painting.
Do not risk damaging your paintings by moving them any more than is absolutely necessary. If you must remove a painting from the wall or move it to another room, clear the pathway of furniture and obstructions and prepare a location to receive it. The frame must be stable and secure. If it is old or there is glazing (glass), ensure that it can withstand being moved. Determine if you can lift the painting safely by yourself. If the frame is massive or the picture is wider than your shoulders, ask someone to help you. If the painting is of a manageable size, lift the frame with both hands by placing one hand in the center of each side. Always carry it with the image side facing you. Remove jewelry, tie clips, belt buckles, or other clothing that might scrape the surface. Hang paintings from picture hooks (not nails) placed securely in the wall; a heavy picture requires two hooks. Before hanging, examine the back of the painting to ensure that the hanging hardware is strong and secure. If the painting is framed, the hardware should be attached to the back of the frame, not to the stretcher or strainer. If picture wire is used, attach a double strand of braided wire to the sides of the frame (not to the top edge) with "D" rings or mirror plate hangers (see diagram). These types of hangers are secured to the wooden frame with two to four screws. Hanging can be more complicated with contemporary paintings that do not have protective frames. Moving and hanging unframed or large paintings safely may require the services of professional art handlers, who may be reached by calling a local museum, historical society, or reputable art gallery.

FRAMING

If you intend to buy a new frame for a painting or have a painting treated by a conservator, take the opportunity to have it properly framed. Ideally, a painting should be held in the frame with mending plates that are attached to the frame with screws. Brass mending plates can be bent and adjusted so there is light pressure on the back of the stretcher or strainer. Sometimes nails are used to frame paintings, but nails can rust, fall out, or protrude through the canvas. Ask the framer or conservator to pad the rabbet, the part of the frame that touches the face of the painting, with felt or another suitable material to protect the image.

HOUSEKEEPING GUIDELINES

After carefully examining your paintings for loose or flaking paint, dust them every four to six months. Feather dusters can scratch paintings. Instead use soft, white-bristle Japanese brushes, sable (such as a typical makeup brush), or badger-hair brushes (called "blenders" and used for faux finishes). Never try to clean a painting yourself or use any liquid or commercial cleaners on a painted surface. Commercial preparations can cause irreparable damage to the fragile layers of a painting. Avoid using pesticides, foggers, air fresheners, or furniture sprays near artworks. Remove paintings from a room before painting, plastering, or steam cleaning carpets or wallpaper. Return the artworks only when the walls and floors are completely dry.

DISASTERS AND OTHER PROBLEMS

If a disaster such as a flood or fire occurs in your home, remove paintings from standing water or debris. If the paint is flaking, lay the painting flat with the image side up to limit paint loss. Consult a professional conservator as soon as possible for assistance in limiting damage to your artwork. Wiping smoke, mud, or other contaminants from a painting may result in additional damage. An information packet on disaster recovery is available from the American Institute for Conservation.
Other problems will require the help of a professional conservator. Insect infestation, flaking paint, paint loss, torn canvas, cracks with lifting edges or planar distortions (wrinkles or draws in the canvas), mold growth, grime, or very discolored varnish are problems that only a professional conservator is trained to address.

RESOURCES

Schultz, Arthur W., ed. Caring for Your Collections. New York: Harry N. Abrams, Inc. 1992.
Stout, George L. The Care of Pictures. New York: Dover Publications, 1975.
This brochure is provided courtesy of the American Institute for Conservation of Historic and Artistic Works (AIC), the national membership organization of conservation professionals dedicated to preserving the art and historic artifacts of our cultural heritage for future generations. Among other services of the AIC is the Guide to Conservation Services, which provides a free list of conservators in your geographic region. The AIC brochure Guidelines for Selecting a Conservator, will help you make an informed choice.

The recommendations in this brochure are intended as guidance only, and AIC does not assume responsibility or liability.



THE CARE AND PRESERVATION OF OIL PAINTINGS
Mary Fahey, Head of Preservation/Chief Conservator, The Henry Ford

Oil paintings can be maintained for years of use and enjoyment provided that some basic care and attention is given to their preservation. The conservation staff at The Henry Ford have compiled the information in this fact sheet to help individuals care for their objects and collections. The first step in the care of collections is to understand and minimize or eliminate conditions that can cause damage. The second step is to follow basic guidelines for care, handling and cleaning.

Contents:
Causes of Damage and Guidelines for Care
Light Levels
Temperature and Humidity Levels
Dirt
Improper Cleaning
Insects
Careless Handling
Bibliography
Suppliers
References

CAUSES OF DAMAGE & GUIDELINES FOR CARE

The primary cause of damage to oil paintings is the storage or display of paintings in inappropriate environments. This includes display or storage in areas where there is excessive exposure to light, high and/or fluctuating temperature and humidity levels, dirt or insects. Damage can also be caused by careless handling and the improper cleaning of paintings.

LIGHT LEVELS

Excessively high light levels can cause the fading and/or darkening of paintings. Some paintings darken so severely that the painting and its details are no longer visible. In order to avoid damage caused by light, paintings should be displayed in dim areas where no direct sunlight is allowed to fall on them. The suggested light level for paintings is 200 lux. Light levels can be measured using the light meter in a 35mm camera
(see CCI ICC NOTES 2/5 listed in Bibliography).
High light levels also can cause damage due to excessive heat build up. The use of lights that are positioned close to the paintings such as the commercially available lights that are mounted to the frame or directly above it should be avoided. Diffused spotlights should be mounted at least 10 feet from the painting to avoid potentially damaging heat buildup.

TEMPERATURE AND HUMIDITY LEVELS

Extremes and fluctuations in temperature and humidity can cause damage to paintings due to the expansion and contraction of the wood and fabric components of the painting. Wood and fabric absorb moisture which causes them to swell on humid days and conversely shrink on dry days. Paint, however, is not as resilient and can crack and flake off as a result of expansion and contraction of the underlying wood and fabric structure. These dimensional changes can cause the canvas to become slack and sag during the winter months. Most fabric paintings are secured to a wooden frame that is commonly referred to as a stretcher or strainer. Stretchers are equipped with expandable corner joints that can be adjusted to insure that the painting remains taught. The joints can be expanded by driving small wooden wedges into the interior corners of the stretcher at the back of the painting. This procedure is commonly referred to as "keying out" a painting. Paintings should not be keyed out during the winter months when the humidity is low. The increased tension caused by keying out may cause the painting to tear as the wooden stretcher expands during the humid spring and summer months.The proper display and storage of paintings can be achieved by monitoring the environment in various rooms in order to identify the best area for display or storage of paintings. Acceptable temperature and humidity levels for paintings are as follows, keeping in mind that fluctuations should be kept to a minimum.
Winter
Temperature 65-70 degrees FRelative Humidity 40%-45%
Summer
Temperature 70-75 degrees FRelative Humidity 45-55%
Inexpensive temperature and humidity sensors can be purchased from conservation suppliers. While precise control of temperature and humidity is desirable, it is not always practical in homes. Therefore, damage should be minimized by avoiding extremes in temperature and humidity. This can be done by insuring that paintings are kept away from heat sources such as furnace vents, fire places, warm lights and direct sunlight.Excessive humidity, as can be found in most basements, should also be avoided since it can cause mold growth that can stain the surface of the painting.

DIRT

Aside from the unsightly appearance of dirt on a painting, dirt also serves as a host for mold growth and the absorption of pollutants and moisture onto the surface of a painting. All of these can cause damage that obscures the image of the painting.Paintings should not be displayed in smoking areas or in close proximity to candles or fireplaces which can deposit nicotine and soot onto the surface of the painting.

IMPROPER CLEANING

In general, the cleaning of paintings should be left in the hands of a trained conservator. However, there are some simple procedures that can be followed to increase the longevity of a painting. Soft brushes can be used to remove surface dirt from paintings and frames. When dusting an oil painting care should be taken not to flex the canvas or to dislodge paint chips by bumping the painting. Paintings that have loose flaking paint should not be dusted as fragments of paint could be dislodged and swept away. The back of the painting should be kept clean by brushing or vacuuming. In order to clean the back, the painting should be removed from its picture frame and placed face down on a clean surface. Excessive dirt should be vacuumed using a small low suction nozzle with a brush attachment. Proper framing with a dust cover on the back of the painting will prevent dirt from accumulating behind the painting. Holiday decorating in a manner that will cause damage to paintings should also be avoided. Live greens and berries can stain and damage frames and paintings. They also introduce pests into the environment.If surface dirt cannot be removed by dusting, cotton swabs that have been dampened with distilled water can be lightly rolled on the surface to remove dirt. Again, if there is flaking paint no attempt at cleaning should be made.

INSECTS

Insects that can cause damage to oil paintings include carpet beetles and powder post beetles.Carpet beetles generally subsist on protein-based materials that may be included as a sizing material on canvas paintings. Insects are most often are found at the back of the painting between the canvas and stretcher. Holes in the canvas, or the presence of worm-like insects or furry carcasses are an indication of carpet beetle problems.
Powder post beetles characteristically bore small holes (approx. 2mm in diameter) into wooden materials. These holes are generally the first visible evidence of powder post beetle infestation. Frass, a substance that looks like saw dust, is also a good indication of an active infestation. Paintings should be routinely taken down and examined for pests. If evidence of infestation is found, the object should be placed in a plastic bag and isolated until it can be examined by a professional conservator.

CARELESS HANDLING

The greatest amount of damage to artifacts is caused by careless handling. Prior to moving a painting, be sure to remove all jewelry, belt buckles, etc. so that the painting is not accidentally torn or scratched while being moved. When moving a painting, always be sure to grasp the painting from both vertical sides. Do not hold a painting at the top of the frame or by its hanging wire. Also be careful to insure that the picture wire does not puncture the back of the painting during the move. It is important to avoid bumping canvas paintings as even the slightest bump can cause future cracking of the paint surface.

Further information on the care of paintings can be found in conservation literature listed in the attached bibliography.

BIBLIOGRAPHY
A Handbook on the Care of Paintings Caroline Keck. Watson-Guptill Publications 1965Conservation and Restoration of Works of Art and Antiquities Volume I. Herman Kuhn. Butterworths, London 1986Conservation and Exhibitions. Nathan Stolow. Butterworths, London 1987 ICC CII NotesThe Canadian Conservation InstituteNotes 10/8, 10/9, 10/12, 10/1, 10/2, 10/3, 10/4, 2/5 1030 Innes RoadOttawa , Canada613-998-3721(Good reference s for care and framing; accompanied by good illustrations) The Museum Guide to Pest Control. Zycherman, Schrock. Foundation of the American Institute of Conservation 1988Art Objects their Care and Preservation. Freida Kay Fall. Lawrence McGilvery Co. 1973Dirt and Pictures Separated. United Kingdom Institute for Conservation of Historic and Artistic Works. Papers given at the Tate Gallery. January 1990Conservation of Paintings and Graphic Arts. International Institute for the Conservation of Historic and Artistic Works Preprints of Lisbon Conference. 1972.



SUPPLIERS
Framing Materials, Brushes, Humidity IndicatorsUniversity Products 517 Main Street PO Box 101 Holyoke , MA 800-762-1165
Light Impressions, Inc. PO Box 2376 Brea , CA 92822-2376 (800) 828-6216 (800) 828-5539


REFERENCES
For a listing of conservators in your area, please contact:
The American Institute for Conservation of Historic & Artistic Works1717 K Street NWSuite 301Washington, DC 20006(202) 452-9545


The recommendations on this blog are intended as guidance only and blogger: Art Diva of Paintingstogo.com, paintingstogo.com and Paintings To Go, Inc. do not assume responsibility or liability.