The Care and Preservation of Oil Paintings

0il 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

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 F
Relative Humidity 40%-45%
Summer Temperature 70-75 degrees F
Relative Humidity 45-55%