Bolus base

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The gilding of the gold background image (detail) is badly damaged so that the red bolus background is visible.

In painting, the term bolus basically has two meanings:

The bolus base has "grown" through the layer of paint on top and has discolored it red.

1. The bolus base ( bolus ), which was finely ground and slurried as a soft, elastic base for the old masters' poliment gilding ( gold base picture ) and

2. the bolus primer, which has been used as a primer since the 16th century in painting by the old masters on textile picture carriers ( canvas paintings ).

For the poliment gilding , the artists used the more clayey, easy-to-polish so-called "fat" types of ocher in shades of yellowish-white, yellow, red and black. These colored bolus grounds can be traced back to around the 15th century in connection with poliment gilding. In the 13th, 14th and 15th centuries, artists south of the Alps mostly used the red, occasionally whitish-yellow bolus , which they ground with egg white. North of the Alps, whitish gold bases predominated until the 14th century, which were initially replaced by yellow, and towards the middle of the 14th century gradually by red bolus bases .

In painting on textile picture carriers , the bolus ground is used in Venetian painting for the first time since the 16th century. Mostly it is red to black-brown primers, which are usually made up of so-called "lean", i.e. H. grainier varieties of ocher were produced. The technique of placing a colored primer under a layer of paint spread, starting from Venice, first in Italy and in the 17th and 18th centuries was also used in Germany and the Netherlands on textile picture carriers ( canvas paintings ).

disadvantage

Colored ocher grounds could "grow through" under certain conditions; That is, the color of the red or red-brown primer was visible through the layer of paint above it. This "discoloration" can occur so intensely in 17th century paintings that the effect of the picture is strongly influenced. It is not yet clear why only certain colored primers grow through while others do not. It is believed that the ocher used in these cases contains very fine pigment particles that were able to "migrate" into the overlying color / pigment layer during the oxidation process and discolor it.

literature

  • Knut Nicolaus: DuMont's handbook of painting . DuMont Buchverlag, Cologne 2003. ISBN 3-8321-7288-2 .

Individual evidence

  1. ↑ Knut Nicolaus: DuMont's picture lexicon for determining paintings . DuMont Buchverlag, Cologne 1982, ISBN 3-7701-1243-1 , p. 44 .
  2. ↑ Knut Nicolaus: DuMont's picture lexicon for determining paintings. DuMont Buchverlag, Cologne 1982, ISBN 3-7701-1243-1 , p. 63 .