Consolidation of Acrylic and Oil-Based Paintings with Cellulose Nanofibers ^†

Nowadays, more than ever, cultural heritage is linking humanity to its history. In order to preserve different artifacts, multiple modern techniques have been developed and, under this context, a new method for protecting pigments in paintings has been achieved. Over time, the intensity of colors tends to fade due to numerous degradation agents present in the environment. These factors affect the paintings, and there is a growing need for new consolidation materials that do not interfere with the original work. Cellulose nanofibers (CNFs) have the potential to be a new innovative material for the consolidation of paintings’ canvases [1].

In this work, two different types of paints were used: acrylics and oils (blue, red, yellow and green). CNF 4.5% was chosen as a consolidant, and one batch of the samples was treated with this solution on the color layer and another batch on the back surface, directly on the canvas. After that, the samples were exposed to direct sunlight for 54 h; before and during the exposure four types of tests were performed: colorimetry, glossmetry, FT-IR and Raman spectroscopy for the determination of the effects of the sun on the pigment layers [2].

The colorimetric measurements revealed that the untreated samples supported the highest color degradation, whereas the ones treated with CNF on the color layer supported the lowest degradation. Glossmetry showed that overall, the samples lost the gloss at the same rate, regardless of whether the CNF was present or absent. Furthermore, FT-IR and Raman spectroscopy indicated the presence of functional groups specific to the degradation process, as shown below for the red oil color (Figure 1).

Following the tests performed so far, it can be said that CNF has a good consolidation effect when applied to the color layer. In the future, the samples will be exposed for longer periods of time for degradation, and more detailed tests will be performed.