Dot blot immunochemical and infrared analyses of the adhesive layer applied to the painting Imago Pietatis by Domenico Morone

Purpose To investigate the nature of the materials used in the adhesive layer of the Imago Pietatis painting (end of the fifteenth century-beginning of the sixteenth century) by Domenico Morone as a prerequisite for its restoration. Methods Micro-FTIR spectra of the animal glue and a polished cross-section were acquired by a Jasco IRT3000 spectrometer, equipped with a 32x Cassegrain objective. A dot blot immunoassay was used to characterise a minor component of the adhesive layer. Results Micro-FTIR was used as an effective diagnostic tool to detect the major component of the adhesive layer and the binder of the paint. Despite the ageing, the complex matrix and the micro-size of the sample, using a dot blot immunoassay, it was possible to quantify 3.7 +/- 2.0 ng of ovalbumin per microgram of sample (corresponding to 0.004 +/- 0.002% of the weight). Conclusions The findings were in line with conservation practices described in the old treatises, confirming the correct interpretation of the adhesive layer compounds added to the painting and suggesting for the cleaning the use of an anionic water-soluble surfactant highly effective in the removing of proteinaceous materials.

Automated summary

This study investigated the nature of the materials used in the adhesive layer of a painting by Domenico Morone and provided guidance for its restoration. Micro-FTIR spectra and dot blot immunoassay were used to analyze the composition of the adhesive layer. The results successfully detected the major component of the adhesive layer and the binder of the paint, as well as quantified the content of ovalbumin. The findings are of great significance for the conservation and restoration of the painting.