This blog post (and the next two that follow) is probably of little interest unless you are an iconographer. However, for those who are interested, especially fellow icon painters, you might find something helpful for your own work.
This past week I've been working on the San Damiano Cross, preparing for highlighting the garments of the figures to either side of the central image of Jesus.
For today, I want to say a few words about highlighting blue garments. (I'll be writing about highlighting a green garment and then highlighting a garment of one color by using an entirely different color in Parts II and III)
Green is a challenging color to highlight and blue, at least for me, is even more difficult. Getting the underpainting, then the highlighting color and finally the highlights themselves to all come out right, for me at least, is usually challenging.
We'll start with blue. In antiquity and in medieval painting, the most commonly used blue pigments were blues made from naturally occurring minerals (lapis lazuli/ultramarine blue and azurite/azurite blue) and blues manufactured from admixtures of copper salts. Beginning in the 19th century, a variety of blue artists colors have become available, including, but not limited to artificial ultramarines and azurites; cerulean, manganese and Prussian shades of blue and of course, cobalt blue.
However, in the medieval icons and Western religious paintings, the expensive and difficult to obtain azurite and ultramarine were commonly used by artists and iconographers. True ultramarine, made from the precious stone lapis lazuli (mined then as now in Afghanistan) was very expensive and used sparingly. In the West it was reserved for the blue overgarment of the Blessed Virgin or for backgrounds requiring an intense, rich blue. In Russia, art historians believe that the blue used by Saint Andrei Rublev for the undergarment of the central figure In the Trinity was true ultramarine.
Fortunately, there are modern substitutes for these two blues - Sennelier, the French colorists, produce a beautiful substitute azurite blue available as a dry pigment or in acrylic. Since true azurite comes in a variety of shades, including greenish-blue, the shades of blue in icons painted with azurite tend to vary.
In my own work, I tend towards doing the underpainting of blue garments in a somewhat blue-green shade of azurite. Rather than mixing a blue-green shade, I apply a mixed greenish glaze over the azurite blue. I prefer this because I've found that otherwise applying the highlights to the unglazed azurite blue gives results that have too much contrast to them.
Once I've applied the greenish glaze to the blue underpainting of the garment, I do the highlight in a mixed color that combines cerulean blue, and tiny dabs of ochre and vermilion, Pere Igor, in his book, "The Icon: Image of the Invisible: Theology, Aesthetics and Technique" termed this brownish gray color, ditch.
This mixed color, ditch, with a bit of white added to it, makes it possible to softly model the abstract pattern of folds in the cloth characteristic to icon painting. Ditch makes it much easier to create a seamless transition from the three progressively brighter and reduced highlights. It is much better than trying to add white directly to a pure shade of blue, which in my experience results in a muddy, opaque highlighting color.
At some point I'll blog on how much highlighting is too much, not enough and just right. But for now we'll focus on getting the underpainting and the highlighting color.
Part II on highlighting green garments will be up next.