Art Conservation and Painting Care
Paintings are made up of several layers, from the support onto which the ground is applied to the paint that covers the ground and creates the image. The support can be made of nearly any material but is typically cotton canvas, linen, wood, masonite or plaster. The support is often, but not always, primed with either an acrylic gesso or rabbit skin glue and a solid layer of paint. The paint itself is often chemically complex, containing synthetic or earth pigments suspended in oil, acrylic, tempera, wax or other mediums. These elements are normally very stable, but exposure to environmental changes or improper storage conditions can result in cracking, blistering or discoloration.
One of the most common causes of discoloration on paintings is yellowing varnish. As a general rule, varnish is meant to protect the paint surface by covering it and catching any airborne grime. Discolored varnish can be professionally removed with gentle solvents without harming the paint layer. In certain situations, when varnish is applied before oil paints have dried, extra care must be taken to ensure that the paint is not removed along with the varnish. Structural damage such as cracking, flaking or fungi growth can also be treated by a painting restoration specialist.
ENVIRONMENT FOR PAINTINGS
Where a painting is stored or displayed, and even how it is hung on the wall, can greatly affect its longevity. Depending on the type of paint used, humidity may cause cracking or peeling. Ideally a painting should be stored in an environment that is comfortable for people, around 70 degrees Fahrenheit, and with a relative humidity between 40 and 60 percent. Drastic changes should be avoided as well.
A simple backing board attached to the wooden stretchers helps to keep dust and debris off of the normally raw reverse side of the canvas and can protect the object during handling. This backing should be sealed with no space for air to enter. All paintings should be hung by picture wire strong enough to support the weight of painting and frame. The wire should be stretched fairly taught from one side to the other. We recommend using a hanger attached to the frame with two separate screws. Do not use eye screws as these can pull out. Paintings should always be hung by picture hooks appropriate for the weight of the piece – never on nails. If hung on an exterior wall it is recommended that small rubber bumpers be placed on the back of the painting to allow air to circulate behind it. A thin insulating board may also be used to isolate the back of the painting from an exterior wall.
Paintings should not be displayed over a working fireplace as this will expose them to heat and soot, causing significant damage in a short period of time. 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.
Paintings should never be in direct sunlight which can cause faded colors and other types of damage. Halogen lights are a poor choice since they emit damaging ultraviolet light. Lights that attach to the top of the paintings are also not recommended. If these should ever become loose and fall they may scratch or rip the canvas. Recessed ceiling lights, track lighting and color-balanced incandescent or tungsten bulbs are the best choices.
FRAMING OF YOUR PAINTINGS
Ideally a painting should be held in the frame with metal offset clips 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.
Paintings should never be stored in damp areas such as basements, nor should they be left in attics where temperatures can greatly fluctuate. Ideally paintings should be hung on a wall even when in storage, but they may be stored vertically with stiff boards protecting the front and back of each painting.
Paintings should be moved as little as possible. Whenever paintings are handled they are at increased risk of damage. If you must move a painting, be sure that your path from location to location is clear so that you do not have to maneuver around furniture or obstacles. For larger works lift with one hand on the bottom and one on the side to keep the piece steady. Smaller works may be carried by holding each side. Unless a painting has flaking paint it should be carried vertically just as it was hanging on the wall. Any wires that may be loose and hit the back of the painting should be secured and all hardware should be inspected before the painting is re-hung. Care should be taken so the painting does not rest on the stretchers as this can leave marks and indentations.
Do not lift the painting using the top of the frame or stretcher as these areas can break under the weight of the whole painting. If the painting is too large for one person to lift properly, have a second person help lift and carry it. If the painting is to be set on the floor or leaned against a wall it should be slightly elevated on small padded blocks.
Paintings should be inspected every six months in order to identify any problems before they become too severe. Paintings may be lightly dusted with a sable brush (never a feather duster) and only after checking for any loose, flaking paint. Do not use solvents or liquids of any kind on the painting. Aerosol sprays such as air fresheners, window cleaner, furniture polish and foggers should never be used around paintings. It is also important to remove paintings from the room when painting, plastering or steam cleaning carpets.
If a painting is in an area that has been flooded or fire-damaged it must be removed and taken to a conservator or painting restoration specialist. If there is any sign of flaking paint lay the painting flat with the image facing up. Do not wipe smoke, soot or debris from the surface as this may loosen paint and cause severe damage.
Insect infestation, flaking paint, paint loss, torn canvas, cracks with lifting edges, wrinkles or draws in the canvas, mold growth, grime or discolored varnish are all problems that only a professional conservator is trained to address.