Effect of water in color changes of historical paintings

In conservation and cleaning of historical paintings, the use of water was discouraged because of its effects in terms of swelling and leaching of pictorial materials and of color modification. Nevertheless, water can represent a good substitute of organic solvents and of other tools recently employed for cleaning and restoration. The research article assesses the wetting characteristics and to quantifies the effect of the water absorption on the color changes for historical paintings. For these purposes, different typologies of painting mock-ups have been prepared in the laboratory to reproduce the main antique pictorial techniques. The results highlighted that the binder played an important function in the wetting properties assessed by contact angle measurement. The water absorption tests underlined that the topography of the painting surface strongly influenced the water absorption. The data have been correlated to colorimetric measurements to quantify the color alteration induced by water. This quantification is important to define the role of water-based products in cleaning and conservation procedures. The water, in fact, could be a good tool of green chemistry to save the health of the restorer and the environment.