Chromatic reintegration in marbles of historical heritage. Evaluation of its effectiveness and durability outdoors

Abstract

The architectural and sculptural heritage elements exposed to environmental decay (polychromed or not) determine the choice of painting techniques, pigments and binders needed for the chromatic reintegration. A coincidence with the tone of the stone support altered is required, determining the chromatic modifications of the pictorial means employed in the chromatic reintegration. Specimens of pure white marble (Type A and B, from Macael-Spain) have been used as support to assess the chromatic reintegration techniques (oil, tempera and encaustic), from eleven binders and two white pigments (O2Ti and O2Sn). All the samples were exposed to natural aging and accelerated decay agents, such as: UV aging and heating and H2O aging. The main results indicated a substantial color variation in the reintegration materials, basically a loss of luminosity and subsaturation, and a slight tonal skew towards yellow. Similarly, in the marble supports, noteworthy shifts were observed, such as darkening and yellowing.