PR106

The stuff of legends-- the fire of an alabaster cheek and the red of Rembrandt, with all the toxicity of a volcanic hot spring. But alas, in addition to toxicity it is not quite as lightfast as we would hope. Still, some samples have survived. The natural mineral is called Cinnabar whereas the synthetic form is called Vermilion.

A bright red indistinguishable in masstone from some cadmium reds, however it mixes a bit differently and tends to be semi-opaque. Debate about its lightfastness has tended to be one of those things which "springs eternal". We were fascinated to see lightfastness tests from the legendary Gunzorro (one can find his vermilion tests here). Similar findings were echoed independently by Virgil Elliott. Unfortunately this pigment which has captivated painters does indeed seem to darken with enough light exposure. Whether the darkening is due to mode of manufacture (wet or dry process— with the dry process seen as better) or whether the darkening may be due to adulteration with another pigment would require lab testing to determine.

We have heard that the sometimes-quoted ASTM designation of ASTM I has to do with the length of time the ASTM requires for the exposure, and that perhaps were the exposure requirements a bit longer vermilion would undergo the blackening that it so often exhibits in the studio tests done by painters. Perhaps notably, Natural Pigments mentions that glazing madder lakes over Vermilion may help to mitigate this tendency to darken. There is discussion that the way it is manufactured may make a difference to its lightfastness as well as a note that the natural mineral may fare better than the manufactured versions.

It has become difficult to ascertain the quality of various tubes of Vermilion as they are sometimes cut with fillers or may even have Cadmium Red standing in for the genuine pigment. It's said that some of the duller versions of vermilion may be substandard representations of what this pigment can be, or perhaps used to be. On the other hand there are some brilliant cadmiums that are difficult to distinguish from the better versions of vermilion which poses a different challenge. There may be some simple studio tests for distinguishing genuine vermilion from cadmium.

Also it is said that genuine vermilion is very slow drying, which is interesting because it has rather lean oil requirements when made into a paint, according to Virgil Elliot's book In Traditional Oil Painting.

In terms of hue, the great Gunzorro once described PR106 as somewhere between red earths and the cadmiums.

There are at least two different main color groupings within Vermilion. There are two varieties of Vermilion which tend to be the orangey kind, and these are in contrast with the Chinese version, which is a cooler red. The former types—the orangey ones— are associated with the Imperial kind (or Monte Amiata Imperiale) form of vermilion, which also makes warmer pinks when used in tints.