Some time back in 2012 I read Virgil Elliot’s Traditional Oil Painting. He refers to Burnt Umber as a Problematic Pigment:
The author [Virgil Elliott] has all but dropped burnt umber from his palette, owing to its high degree of absorbency when dry, which causes varnish to sink in, leaving chalky-appearing “dry spots.” It can be useful as a minor ingredient in a paint mixture when faster drying is desired, such as in instances where raw umber would not produce the right color. Both burnt umber and raw umber are essentially clays, which have a natural tendency to shrink when dry and swell when saturated with a fluid. However, since burnt umber undergoes a heating process in its creation, it is the worse of the two in that regard. Raw umber does not seem to be quite as problematic.
Also around that time I was having a series of phone conversations with some of the employees at Kremer in Germany and was advised not to use umbers at all (burnt or raw) in that they tend to creep to the surface (I’m paraphrasing), and unfortunately I didn’t ask for an explanation with regard to the chemistry.
Jump to September of 2013 when my research into alkyd mediums led me to a paint maker named Pip Seymour. Not knowing where to buy his paints in Rome, I called him. I was so pleased to discover that he was both amenable and patient in helping me better understand the chemistry behind painting that he readily became a victim of his kindness; the more answers he provided, the more questions I asked. In a follow-up phone call I decided to get his analysis of burnt umber and, in my effort to keep the question as succinct as possible, I decided to phrase the question with a touch of drama: “Is burnt umber evil?”
In essence, his opinion was to keep it simple (which he wisely applies to most of his analyses). He did suggest the importance of stand oil as a binder/medium with such a color in that it helps to keep the pigment particles even as they dry. He went on to say, “Changes in surface appearance may enhance the aesthetic within a painting – but that understanding can alter over time just as the organic composition of all oil paint layers can change. The most crucial factor is the realization of the image at the moment of creation.”
A couple of days after that phone call, I sent him the following email:
An extraordinarily bizarre thing happened on the evening after our last discussion: I was organizing some of my many, many PDF files on technical analysis, when one in particular caught my eye. It was on Caravaggio’s time in Malta, and, as I had just finished reading a technical analysis on the Beheading of John the Baptist, I chose that one to read before going to bed that night.
Now, you may remember that my second question to you last Friday was, “Is Burnt Umber evil?” Evil seemed the best word to sum up what I had read previously on the pigment, especially in light of Virgil Elliot’s call for its banishment from the palette.
Well, low and behold, that night I read the following from Caravaggio and Paintings of Realism in Malta by Roberta Lapucci:
“The defect of this technique [working over a dark priming] is that, with time, the chromatic balance is altered, reinforcing the shadows and absorbing the half tones. Burnt umber has a unique chemcial characteristic; during the drying process of the pictorial film, its manganese molecules tend to migrate towards the external surface to absorb oxygen (the element also needed by oil when it polymerizes). Therefore, by rising up to the pictorial surface, burnt umber eats out the half tones and reinforces the shadowy areas. However, it does not pass through lead white, thus increasing the contrast even more. Such a dark priming layer is used with a chromatic function ‘but not… en reserve’ rather ‘to intensify the contrasts, to make the pictorial layers vibrate and to absorb lights’; some white strokes ‘hardly can cover the dark ground’.
“In 1681 Filippo Baldinucci defines burnt umber as ‘a natural colour, of dark hair tonality, used to pain and to put in the priming layers of canvas and panel paintings. This is held by the best painters to be an evil color; it has such a desiccative power that is does not work well in the priming layers and in the oil layers also due to the other poor qualities, it makes colours change; which is why it fooled many artists, who used it in their canvases, even those who were very good in colour rendering’.” (Yes, it reads “evil”! It was a Twilight Zone moment.)
So there, fellow painters, is the chemistry behind umber… and even a moral judgement! But is it evil? I am still undecided. But I am trying some new browns with a mixture of yellow earth, red ochre and black.