Tattoo Wall?: study of the stability of an innovative decorative technique through hyperspectral imaging and possible application in the mural painting’s restoration

摘要

The main purpose of this contribution is to report some first preliminary analyses of a new and never investigateddecorative technique named Tattoo Wall?, especially the possible changes due to ageing artificially induced by extremehumidity conditions in view of a possible application in crypts, churches or outside wall paintings. This innovativedecorating technique involves transferring digital images on wall surfaces through a transfer paper with solvent -basedink and fixative. For the experimental tests, we chose to work on a color scale as wide as possible, to test each singlecolor, and on different materials. The printed colors were applied on hydraulic mortar, containing marble powdercombined with Ledan C30, particularly suitable for restoration in environments with high relative humidity (RH%).Moisture ageing was obtained by placing the sample in a box with RH% fixed to 92% thanks to the presence of salts(sodium sulphate deca-hydrated) for compressively two years (96 weeks). Reflectance spectrophotometry for colormeasurements and hyperspectral imaging (HSI) were used to assess the effect of high relative humidity exposure. Theexperimental data were statistically treated in order to evaluate their significance. Testing enabled us to verify thestability and durability of Tattoo Wall? under high relative humidity, with little chromatic alterations. Testing could andshould be conducted also on different surfaces and materials (paintings on canvas and wood, oil on wall, etc.) to make itas complete as possible and guarantee the use of Tattoo Wall? in most cases of pictorial reintegration, reducing the riskof human error.