Paintings are fragile creations which consist of various layers which require special care to ensure their continued preservation. The paint is applied to a support, typically canvas or wood, which is usually 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. 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.
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 and/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 or unstable conditions occur in a painting such as tears, flaking paint, cracks with lifting edges, or mold, consult a conservator to decide on possible courses of treatment for your painting.
Suitable Environment :
Maintaining a proper environment for your paintings is important. 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. Art generally does 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 changing humidity levels than paintings on wood panels, but the dimensional changes that can occur in a wood panel can result in 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 or rapid environmental fluctuations.
Avoiding large fluctuations is very important. A protective backing board attached to paintings like a Fome-Cor (or archival cardboard backing) secured to the reverse of a painting with screws (not staples or tacks) will reduce exposure of the canvas to rapid environmental changes, keep out dust and foreign objects, and protect against damage during handling. Ensure the backing board covers the entire back of the picture; do not leave air vent holes, which can create 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.
Displaying Paintings :
The display of paintings requires careful consideration. Direct sunlight can cause fading of certain pigments, yellowing of varnish, and excessive heating of the paint surface. Paintings hung on uninsulated exterior walls, should have small rubber spacers behind the frame to increase air circulation.
Fireplaces are often a focal point, a painting displayed above a mantel will be exposed to environmental extremes and pollution. Hanging paintings above heating and air conditioning vents or in bathrooms is also inadvisable. The rapid environmental fluctuations will be harmful. Select a safe place away from high traffic areas, movable seating, or other hazards.
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. They can fall into the artwork causing burns or tears. Indirect sunlight, recessed lighting, or ceiling-mounted spotlights are best for home installations.
Pictures are usually safest hanging on a wall, provided they are well framed, with the picture and hanging hardware adequately secured. If you must store a painting, avoid basements, garages, and attics. A good storage method is to place the paintings in a closet. A stiff board (cardboard or Fome-Cor) protecting the image side of each artwork and a backing board on the reverse. Do not risk damaging your paintings by moving or touching them any more than is absolutely necessary.
When removing paintings from the wall clear the pathway of furniture and obstructions and prepare a location to receive it. The frame must be stable and secure. For old or glazed frames, ensure that they can withstand being moved. Where 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 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 plain 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. On framed paintings 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. 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.
If you intend re-framing a painting or conservation work done then take the opportunity to frame it properly. 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 adjusted so there is light pressure on the back of the stretcher or strainer. Although nails are often used to frame paintings, nails are not recommended because they 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 edges of 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 or snag on paintings. Instead use a soft bristle brush, like a white-bristle Japanese-type, sable (typical makeup brush), or badger-hair brushes. 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 touching the surface of paintings with your fingers. The natural oils in your skin can also cause damage or leave marks that may appear later. Avoid using pesticides, foggers, air fresheners, or furniture sprays near artworks. Remove paintings from a room before plastering, painting, or steam-cleaning carpets or wallpaper. Return the artworks only when the walls and floors are completely dry.
Source : American Institute for Conservation of Historic and Artistic Works : Resource Center : Painting. The recommendations in this document are intended for guidance only. AIC does not assume responsibility or liability.