In art, craquelure is the fine pattern of dense "cracking" formed on the surface of paintings, in particular due to the aging of paints. It is often used to determine the age of paintings and to detect art forgery

Art forgery

Art forgery is the creation of works of art which are falsely attributed to other, usually more famous, artists. Art forgery can be extremely lucrative, but modern dating and analysis techniques have made the identification of forged artwork much simpler....

, as craquelure is a hard-to-forge signature of authenticity

Authenticity in art

Authenticity in art has a variety of meanings related to different ways in which a work of art or an artistic performance may be considered authentic.Denis Dutton distinguishes between nominal authenticity and expressive authenticity....

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Authentic

Authentic craquelure occurs because paint dries and becomes less flexible as it ages and shrinks. In the case of paintings on canvas, the canvas slackens as it ages as it cannot endure the long-term stress of stretching. Paint at the center of a painting is the least cracked, whereas paint at the edges is the most cracked, or stressed. The precise pattern of craquelure depends on where, when, and under what conditions the picture was painted. Cracks caused by stretching or slackening the canvas are quite different from cracks due to other factors, such as drying and ageing of the paint. The paint cracks when the stress upon it is greater than the breaking stress point of the paint layer and the paint will crack approximately at right-angles to the direction of the stress, relieving that stress. In the middle of the picture the cracks tend to run parallel to the short sides. They spread from the middle towards the stressed locked edges, while the cracks starting at the short sides curl round. The stress at the corners is more than double that of the center. There appear to be distinct French

French art

French art consists of the visual and plastic arts originating from the geographical area of France...

, Italian

Art of Italy

The history of Italian art is in many ways also the history of Western art. After Etruscan civilization and especially the Roman Republic and Empire that dominated this part of the world for many centuries, Italy was central to European art during the Renaissance. Italy also saw European artistic...

 and Dutch

Dutch art

Dutch art describes the history of visual arts in the Netherlands, after the United Provinces separated from Flanders. Earlier painting in the area is covered in Early Netherlandish painting and Renaissance art.-Golden Age:...

 "styles" of craquelure.

The craquelure is almost impossible to accurately reproduce artificially in a particular pattern, although there are some methods such as baking or finishing of a painting wherein this is attempted. These methods, however, can get a crack at most uniform in appearance, while genuine craquelure has cracks with irregular patterns. The precise pattern depends on chemical characteristics of pigments used—from the finest light colors to the less perceptible dark, the painting style of the painter, and whether wood or canvas was used as a background. It also furnishes a record of the environmental conditions the painting has experienced during its lifetime, such as temperature and humidity, and can also reveal details about the painting's history of handling, transportation, and restoration

Art restoration

Art restoration is related to art conservation. Restoration is a process that attempts to return the work of art to some previous state that the restorer imagines was the "original". This was commonly done in the past...

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Induced

Induced craquelure gives new objects such as ceramics and furniture an "antique" look. The effect is achieved by a chemical reaction that results in regular-looking craquelure. The regularity is given by the thickness of the product applied, which can be mixed with bitumen of Judea or oil paints. Flatting and cracking can be replaced by shellac and gum arabic. Art forger Tony Tetro

Tony Tetro

Anthony Gene Tetro , known as Tony Tetro, is an art forger known for his perfectionism in copies of artwork produced in the 1970s and 1980s. Tetro never had formal art lessons, but learned from books, by painting and experimentation. Over three decades, Tetro forged works by Rembrandt, Joan Miro,...

 discovered a way to use formaldehyde

Formaldehyde

Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

and a special baking process.

In recent years the modern decor industry has used the technique of craquelure to create various objects and materials such as glass, ceramics, iron. This was made possible by the use of marketing kits that react with the colors used in decorative acrylic colors. The extent of craquelure produced varies according to the percentage of reagent and time of use. To highlight the cracks, glitter powder—usually available in copper, bronze and gold—is used. Mixing different brands of ready-made products to mimic craquelure results in various sizes and patterns of cracks. Software programs are available for creating craquelure in digital photos.