EXTENDED METHOD OF RESTORATION RETOUCHING IN THE NEARINFRARED SPECTRUM

Abstract

The overpainted layers reveal the artist�s working process, the way he created his work in different phases until the final painting. Photographing paintings in near-infrared spectrum (NIR/IR reflectography) also provides protection against counterfeit art paintings. This paper investigates the intrinsic properties of colorant twins based on the InfraredArt theory, which expands the knowledge about the light absorption response in the visual (V) and near-infrared spectrum (NIR). The key support for the establishment of such paper is in the infrared procedure which explores new possibilities of restorative retouching based on the interrogation of pigment (color) and determination of its Z value. An extended method of restorative retouching is being studied that can equalize the reflection and/or intentionally make it different in the visible also in the near IR spectrum. This can be one of the retouching methods of restoring to the original state, not only the painting visible to the naked eye but also the overpainting or underpainting drawing, thus obtaining a new method in the final stage of retouching. This method of retouching can be applied to damaged artistically significant and historically important paintings that have interesting copies in the genesis of the painting that are visible under IR light. In addition, the method is also applicable to contemporary InfraredArt paintings that conceal a hidden painting, i.e. which artists have intentionally painted in the lower layer with the intention of being detected and observed by an IR camera. For the study a ZRGB camera was used, that simultaneously records in two spectra, visible and near-infrared areas. Two paintings from two Zagreb museums were conserved and restored in such a way that they confirm the established theses on targeted visible and invisible retouching.