34 The Annunciation retable The more or less untouched polychromy of the retable is, in spite of the amount of loss, still remarkably vivid. Smaller retouches produced a positive effect on the whole. The works were completed with the re-erection of the retable. In order to improve ventilation, especially for the painting, the whole construction was moved forward by about 8 cm. The individual segments lie unattached, one above the other. Two lateral wall anchors and a custom-made hanging of the architrave provide sufficient stability, whilst also allowing room for possible vibrations caused by earthquakes. The treatment of the painting The treatment was carried out over nine workshop periods. Due to the limited progress possible during of the annual two-week working periods, the team had the task of dividing up the treatment into distinct steps. The painting regularly had to be remounted to the retable ad interim, waiting for next year’s measures. The positive side effect of this periodical work was the chance to evaluate the achievement of former measures as well as to correct and adjust the proposed concept. The main challenge was the extreme brittleness of the paint layer and the big hole in the upper left corner of the canvas, which was used by bats as an entrance to their roost behind the retable. Excrements of the bats had caused severe losses in the paint layer, with deterioration of the canvas into a powdery condition in the wider area of the hole (Fig. 46-49). Deformations in the bottom half of the painting, (Fig. 50) surface dirt, and mismatching retouches (Fig. 51) from an earlier restoration attempt, together with very irregularly applied varnish that had become brown emphasised the pressing need for treatment. The first aim was to stabilise the canvas. In order to leave the beautiful and special fabric visible as such, it was decided to stabilise it with local measures and thus dispense with the initially planned lining. The treatment focused on a local intarsia with additional support of the area with a thin Stabiltex polyester and a striplining on all sides of the canvas, both achieved with BEVA 371 (Fig. 52-57). In order to minimise future stress, the painting was re-stretched over a loose-lining (polyester canvas) (Fig. 62).
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