Ultramarine Sickness

Hobbies are a good thing to distract from real life sometimes. As the pandemic unfolds I have found some of the thoughts creeping into sketches and paintings like the last landscape I did outdoors which showed social distancing in real life. This painting came from my imagination, it appears to be a sort of microbe floating around in a gelatinous mass. Maybe it is the immune system fighting off a virus?

Recently I learned that ultramarine blue has a problem with acids... even weak acid will degrade the colour and result in rapid fading. There is a well known phenomenon called 'ultramarine sickness' that art experts use to describe a type of damage that can occur to really old paintings. A painting can literally be sick. On the back of this painting I put some test-strips of ultramarine blue along with other colours, and I applied some diluted vinegar to see what would happen. After about an hour, the ultramarine blue was about half strength, while the other colours were unaffected.

By the way, the grey border, which is part of the painting, was done with potter's pink mixed with some phthalo blue and sennelier yellow. Potter's pink (PR233) was featured in the last blog- after researching it, there seem to be no problems with that pigment so I think I will use it a lot to make landscapes. The main question I face now is, should I abandon the use of ultramarine blue? Ultramarine blue was the first blue paint I ever used, and I have used it in probably every painting in the last 30 years. So dropping it would be a tough habit to break especially after dropping alizarin crimson, another long time mainstay of my palette.

5 x 7 " cold press, watercolour, March 2020