Ultramarine is a highly-valued, brilliant blue pigment naturally obtained from the mineral lazurite, which is the main component in the semi-precious stone lapis lazuli.
Ultramarine-based paints – for instance, lazurite mixed with linseed oil – are known to exhibit a degradation phenomenon, known as “ultramarine sickness” or “ultramarine disease,” that drastically changes the aesthetic and integrity of the artwork, showing cracking, flaking, and/or apparent color change. Our research project is interested in understanding the mechanism of ultramarine paint degradation and determining a means to identify and prevent the onset of such degradation.
We hypothesize that “ultramarine sickness/disease” is the result of accelerated binding medium (e.g. oil) degradation catalyzed by ultramarine (or lazurite), supported by evidence of its catalytic activity in catalytic test reactions. To determine the potential catalytic activity of lazurite toward oil degradation, we study the effect of pigment preparation on lazurite properties and, in turn, catalytic activity toward oil-relevant reactions. Further, we analyze historically relevant paint samples for comparison.
With these areas of focus, we aim to gain a deeper understanding of the ultramarine degradation phenomenon as it naturally arises.