How far should a conservation restoration process go? As the time passes by, materials darken, protective coatings yellow or become opaque, superficial grime accumulates over the artworks, etc. Furthermore, there are some factors that can accelerate their ageing. For example, accidental water exposure or constant high humidity can affect the bond between the different layers in a painting on canvas, causing lifting and losses in the paint layer; a fire place close to an artwork can deposit a layer of soot that will disfigure the aesthetic perception of the piece; air pollution can cause acidification of the materials developing into oxidations, corrosions and stains, etc.
Above all, the most frequent causes of deterioration are damages caused by humans: a lack of care and mishandling when moving artwork from one place to another, or even a restoration treatment if performed by inexperienced hands, can cause irreversible damages.
Luckily, if the worst comes to the worst, the pieces that appear to be completely ruined, can be recovered. It is not an easy task, but in the hands of experienced, skilled conservators, a wrecked piece of art can come back to life, to the point in which the owner can, once again, enjoy it without the disruptions caused by the damages.
With all those things considered, it is necessary to point out that although most damages can be restored, the changes caused by natural ageing of the materials (cracks and craquelure, fading of inks, erosion of stone, abrasions caused by the daily use in antique artifacts, etc,) also referred as patina, are intrinsic to the materials used during the artwork conception, and most of the times should not be lessened.
As the great old master Francisco de Goya already said about restoration of paintings: “…Even the own artist, rising from the death, would not be able to perfectly retouch them now, due to the mellow shades given by the passage of time, which also paints…”
William_Hogarth, "Time Smoking a Picture
