Craquelure

When crackle, Kraklé or craquelure ( e) (French craqueler = can be cracked; craquelé = cracked, cracked ) refers to a mesh-like network of cracks or cracks on the surface of oil paintings, gemstones, paint, glass surfaces, glazes of ceramic articles or facade plasters and paints. In paintings we also speak of Krakelüre. The crackle may be related to aging, but also be brought about as a desired effect artificially with a Krakeliermedium.

Oil paintings, painted surfaces and ceramic objects often have an age-related Krakelüre that arises when the subject is exposed to severe climatic fluctuations. The surface - canvas, wood panel or ceramic - expands according to the humidity or contracts. The paint or lacquer layer absorbs less moisture and therefore can not adapt to the movements of the subsoil; she gets cracks and may even flake off.

Usually crackle is not removed as a natural aging phenomenon in restorations; intervention is only warranted when the color threatens spall. On the other hand, weak or absent Krakelüre in antiquarian items be an indication that they have been restored.

(Also called Krakeliermedium ) With special crackle finish or Krakelierlack, which is available about the craft supplies, an artificial crackle effect can be produced. Crackle finish contracts upon drying, resulting in a pattern of cracks forming. This will often result in a "antique " or "historic " appearance.

In ceramics manufacturing, the crackle is due to different expansion coefficients of substrate and icing already in the fire.

In bright tin / lead glazes (such as the basic glaze in majolica or faience ) after the fire, barely visible, the hairline cracks fill with time in use with darker particles and are thus increasingly visible. Dark and opaque glazes such as the " bottle green " is often used for older stoves are less prone to darkening of crazing, the original appearance remains mostly unchanged over the years.

With glazed stove tiles that need to be particularly resistant to heat, the fine cracks in the glaze are more common. This is particularly desirable in the case of very large tile parts. This is the ceramic robust against breakage due to temperature changes, the less flexible glaze can " go along " with the focus more expansive ceramic body.

Gemstones are artificially crazed by the stone is heated and cooled quickly. With a color polish, the cracks can be further emphasized.

• Painting
• Surface Technology
• Ceramics