Bowl formation

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When the bowl is formed, the flakes of paint of a binder-rich brown paint layer bulge up at their edges. In doing so, they pull the textile image carrier with them, so that it forms a negative structure on its back.

When dishing refers to the paintings customer a bowl-shaped deformation of the image layer. The edges of many of the small picture layers have arched upwards in the shape of a bowl and "carried away" the underlying textile picture carrier, so that it forms a negative structure on the back.

Occurrence

The bowl formation occurs predominantly in dark, mostly brown colored areas rich in binder. Adjacent surfaces of different colors usually show no deformation.

Emergence

The image layer of a painting is a thin, cracked "film" made up of one or more layers of paint. It covers the entire surface of the painting. Compared to its surface, its total mass is small. He reacts accordingly to environmental influences .

Each layer of the picture has its own characteristic equilibrium moisture content . This depends on the relative humidity and the composition of the image layer. When the air humidity rises, it absorbs water vapor ( sorption ), when the air humidity falls it gives off water vapor (desorption). If the vapor pressure between the front and back of a painting differs, so-called water vapor diffusion also takes place. The water molecules migrate through the entire structure of the picture or, in the case of cracked paintings, predominantly through the cracks in age. These processes - they are called permeation - trigger a shrinking and swelling of the image layer and the textile image carrier and thereby a bulging of the image layer clods of certain earth pigments . If the bond ( adhesion ) of the image layer to the textile image carrier is good and the textile image carrier is not sufficiently tensioned, it will be deformed with the image layer. Other causes are probably the high binder content and the hygroscopic properties of the brown earth pigments.

Description in literature

These processes were first observed and described in 1942 by Rawlins, later by Keck and Mecklenburg. In 1984, Berger and Russel measured and recorded the forces in the textile image carrier caused by climatic fluctuations. In 1987 Schaible also made extensive reflections on the phenomenon of bowl formation in canvas paintings.

Effect on appearance

Bowl formations affect the appearance of a painting. Due to the bulging edges, the color clods act like small concave mirrors that reflect the incident light rays in a concentrated manner, so that the shape in a dark layer of paint is often not or only very difficult to see.

literature

  • Knut Nicolaus: Dumont's picture lexicon to identify paintings. DuMont Buchverlag, Cologne 1982. ISBN 3-7701-1243-1

Individual proof

  1. ↑ Knut Nicolaus: Handbook of painting restoration . Könemann Verlagsgesellschaft mbH, Cologne 1998, ISBN 3-89508-921-4 .
  2. ↑ FIG Rawlins: The rheology of paintings . In: Technical Studies in the Field of Fine Arts . tape 10 , 1942, pp. 59-72 .
  3. ^ S. Keck: Mechanical alteration of the paint film . In: Studies in Conservation . tape 14 , 1969, p. 9-30 .
  4. ^ MF Mecklenburg: Some aspects to the mechanical behavior of fabric-supported paintings . In: Report to the Smithsonian Institute . Smithsonian Press, Washington DC 1982.
  5. ↑ GA Berger, WH Russel: The new stress tests on canvas paintings and some of their implications on the preservation of paintings . In: ICOM (Ed.): 7th Triennial Meeting . 84th edition. Copenhagen 1984, p. 84.2.7-84.2.9 .
  6. ^ V. Schaible: New considerations on moisture on canvas . In: Journal of Art Technology and Conservation . tape 1 , 1987, pp. 75-95 .