139 The painting “Purgatory” of the Mary retable Concept The overall aim of the concept was to restore the structural stability of the paint layer and canvas. Due to the neglected and severely damaged condition, measures to improve the visual appearance were urgent. The removal of wax and dirt aimed at improving the appearance and eliminating the catalytic degradation effect of it. The low pH value of the canvas required deacidification.90 Structural stabilisation of the canvas required closing the holes and treating the edges in order to be able to stretch the painting again. However, the concentration on a „pure” conservation treatment would have preserved the painting with an unpleasant appearance. Therefore, the inadequate additions, such as the dark brownish varnish and mismatching overpaints were to be removed to reveal the original surface, thus improving the painting’s appearance. The aim was to regain readability. Retouching focused on the areas of paint loss. In the larger paint loss area in the right lower edge, reconstruction of the female body and flames on the old and new fillings was necessary. The varnish removal as well as the application of a new varnish were decided upon to improve the contrast and colour saturation. Conservation and restoration treatment 91 In this case, the treatment required the demounting of the canvas from the strainer. The initial step involved cleaning the front and back. This included the removal of surface grime and wax drops with Pemulen TR 2 gel at pH 8, with the addition of 30% Shellsol T. The weak and brittle paint layer was treated with a general facing and a brush coat of animal glue (5%) for a first consolidation and flattening. As the test for acidity showed raised values, it was decided to deacidify the canvas with the bookkeeper method. Bookkeeper MgO solution was evenly applied to the back of the painting with a spray bottle, which was repeated twice after intermediate drying. By increasing the pH value to over 7, a buffer was introduced as alcaic reservoir for the future.92 After the removal of the facing paper, it became evident that the adhesion between the preparation and the canvas was still very weak. An additional consolidation was needed.93 As there was not enough space for the raised edges of the colour flakes, the textile support had to be stretched across
RkJQdWJsaXNoZXIy MTI5NTQ=