This recent article about how the yellow pigment used by Van Gogh fades over time caught my attention.
Microscopic x-ray imaging and chemical mapping technology was used to find (maybe verify) that he used Chrome Yellow pigment – a yellow widely available at the time and used by many of his contemporaries. The pale yellow version of this colour goes brown over time (accelerated with exposure to sunlight), so museums are paying ever closer attention to how much light their precious sunflowers are getting.
The multiple use of the word “discovery” in the article made me think at first that the researchers had found something out about the pigment itself. It’s just where my mind went. I suppose, as a painter, I don’t consider it to be much of a discovery to find that Van Gogh used a yellow that was relatively new, very bright, and widely available in his time. In fact I think it’s pretty fucking obvious. But of course, if your painting is absolutely priceless, then I guess you should look at it that closely and act accordingly. Reading the article again, I can see that the writer does not specifically say the researchers made any findings about the pigment in particular.
I know a bit about the history of Chrome Yellow, so I was wondering what the huge deal was about finding it in a Van Gogh. I guess just hard evidence? In his time the pigment had poor lightfastness, but colourmen knew about it. It was also specifically noted by Renoir. The colour fell from popularity in part because of this, but was produced in the same way until processes were discovered in the mid 1960’s that made the straight-up Lead Chromate that Van Gogh used much more resistant to fading. (information here and here)
Chrome Yellow, though now stable, is still toxic (because lead). It has been mostly replaced by manufacturers with Cadmium Yellow, and has become basically a specialty pigment – for die-hards and restorers and such. Cadmiums themselves are toxic, so they in turn are being replaced in many colour lines by Azo pigments. For my money, the Azo just doesn’t cut the mustard compared to a real, highly pigmented, quality Cadmium. Pigments suspended in oil are not terribly toxic to the user, whatever their rating, as long as you don’t get it all over yourself, or ingest it, or throw it in the sink. Good studio practices go a long way.
In any case, Chrome Yellow works good and Vincent paints a mean pot of flowers.