By Doug Eisele
Part 1 of 3 –
Paintings can be protected to some extent from the effects of normal aging by good preventative conservation measures and from physical damage by good hanging, handling and storage procedures. However, time transforms most paintings in one way or another.
While many are resilient, others can be extremely sensitive to both physical and environmental change. Paintings often suffer damage and deterioration both through their natural aging process and from accidents, mishandling, improper storage and display, exposure to extreme or fluctuating temperatures and relative humidity, improper cleaning and substandard restorations.
All the materials used in the creation of a painting exhibit some degree of decay over time. Paintings undergo change during the first six months of their life, as the solvent evaporates and the paint begins to dry. As paint dries, a pattern of cracks (craquelure) can develop. Surface cracks may also be an indication that the artist used faulty materials or techniques.
DARKEN AS THEY AGE
Paintings in oil become more transparent as chemical changes occur over time. Varnish layers begin to yellow and darken as they age and can also become more brittle than the paint itself and form its own crackle pattern or flaking independent of the paint.
Other effects of aging include the change in tone or fading of some pigments, for example some greens may turn brown, blues can go gray and reds can fade. These effects are reduced if the painting has not been exposed to light.
Frequently, the surface of a painting is covered with layers of surface dirt and grime, deposited over time from candles, smoke, fires and general atmospheric contamination. The dirt can settle into the paint layers on unvarnished paintings making it nearly impossible to remove without damaging the paint. A whitish haze can develop in paintings stored in damp conditions where moisture has penetrated the paint layers. This effect is known as bloom.
Paintings are often composed of incompatible materials, each having different reactions to changes in relative humidity, temperature and light. Small changes are absorbed by the materials which are reasonably elastic. This elasticity, however, diminishes with age and eventually the painting cannot absorb the stresses caused by these fluctuations.
Most paintings of any age have had some physical change or damage inflicted upon them. Paintings all run the risk of being scratched, knocked, dented, torn or punctured. The paint layers generally show in time the effect of various sorts of impact
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