Restoration of paintings

First of all, there is the restoration of paintings. This relies heavily on the knowledge of chemistry. Second, for hundreds of years, artists have tried to create something beautiful. Many artists today are desperately trying to create something new. They often use chemistry in their search for new materials. 

Particular emphasis is placed on the side effects of the procedures. The thermal, mechanical, and in particular the chemical effects are discussed from a fimdamental/mechanistic standpoint and are exemplified in the case of the laser-based restoration of painted artworks. Certainly, the interaction of intense laser pulses with organic substrates is highly complex. In fact, in many respects, conventional photochemical concepts would suggest that the laser procedures would be particularly damaging for molecular/organic substrates. Yet these limitations or deleterious influences have been shown, at least empirically, to be avoidable to a large extent. This is best illustrated in the laser restoration of painted artworks. Despite their chemical and structural complexity, excimer lasers can be applied successfully to restoration, and irradiation conditions can be defined under which potentially damaging side effects to the substrate are minimal or at least inconsequential. 

Optical Techniques. The most important tool in a museum laboratory is the low power stereomicroscope. This instmment, usually used at magnifications of 3—50 x, has enough depth of field to be useful for the study of surface phenomena on many types of objects without the need for removal and preparation of a sample. The information thus obtained can relate to toohnarks and manufacturing techniques, wear patterns, the stmcture of corrosion, artificial patination techniques, the stmcture of paint layers, or previous restorations. Any art object coming into a museum laboratory is examined by this microscope (see Microscopy Surface and interface analysis). 

If restoration or preservation is required, a professional is consulted to slow the deterioration, thus giving the work an extended life. With some works of art, this is difficult. Many modem works are made of materials that are difficult to preserve and restore, such as newspaper, poor-quality paint, and experimental materials that may be glued to the surface or mixed with the paint. Many pictures are painted on a poorly prepared surface using very heavy applications of paint in time, the paint will begin to fall off the canvas or other working surface. It is the task of the restorer to do whatever is possible to preserve as much of the work as possible. 

Different chemical skills are needed to repair frescoes. In the Florence region of central Italy there are thousands of them, some badly in need of restoring, yet frescoes are among the most difficult types of painting to restore. Their weakness stems from a lack of cohesion between the base material and the plaster. The fresco technique required... 

Hydrogen peroxide (H2O2) can be used to restore white areas of paintings that have darkened from the reaction of lead paint pigments with polluted air containing hydrogen sulfide gas. 

Attempts at environmental control to stabilise mural paintings were used for the restoration of the paintings in the Tomb of Queen Neferati at Thebes. In this case, the relative humidity outdoors and in the tomb with different numbers of visitors was monitored and compared. The results led to a corresponding restriction in the numbers of visitors allowed into the monument. 

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