There is only one color more expensive and difficult to extract than that of genuine Lapis Lazuli, and that is Tyrian Purple (6,6′-dibromoindigo). Tyrian Purple is a red leaning violet color in the form of a dye which is extracted from the regional snail Bolinus brandaris found in the eastern Mediterranean sea. It takes the secretion of roughly 10,000 of these sea snails to produce just 1 gram of colored pigment, hence the high costs of this color historically and in the present day. Tyrian Purple also goes by the names “Imperial Purple” and “Royal Purple” which goes back to the original usage of this color. Originally Tyrian Purple was used as a dye for the clothing of royalty. Both the colors blue and purple [also saturated colors in general] were a rarity until the 1800’s. Often times to get a purple/ violet color a blue had to be mixed with a red ochre or a cinnabar/ vermilion to approximate a hue.
Generally speaking the color Tyrian Purple is a dye as opposed to a pigment. While dyes and pigments can theoretically be used for the same purposes dyes tend to be less lightfast than pigments and better suited to staining things, rather than being used to paint with. A dye essentially dissolves into its binder, whereas a pigment is always a separate entity from its vehicle and is prone to separation. In this research blog entry, I am going to be exploring Tyrian Purple used within oil painting as a pigment would be used. There isn't much information regarding Tyrian Purple's use within oil painting, so I took it upon myself to run it through some tests and even use it in a final painting that conceptually and aesthetically highlights Tyrian Purple as a color!
I am going to show some examples of the usage of Tyrian Purple as a dye for clothing
Byzantine robe, 11th century
Burial Shroud for Emperor Charlemagne, 814
Like the color blue, purple/ violet was a color very difficult to obtain and most often reserved for royalty- sometimes by law. These fabric examples display Tyrian Purple being used for its primary use as a dye for clothing. As I have stated above Tyrian Purple is first and foremost a dye, which means that its historical application within oil painting will inevitably be limited, similar to other dyes occasionally used for painting. For this reason, I have taken it upon myself to test how Tyrian Purple behaves when bound in walnut oil as a vehicle. Similarly to my research on Emerald Green and Mummy Brown, I will be running Tyrian Purple though tests that test its lightfastness when exposed to 3 months of sunlight, reactivity to sulfur [mixed with cadmium yellow], permanency, and transparency. Just like with Emerald Green and Mumy Brown I will be taking a hue and a color that is similar in its physical makeup and run it through the same tests. The hue color will be "Dioxazine Purple", which is generally one of the most reliable and "go-to" options when a single pigment violet color is wanted. The similar color in makeup will be a genuine Indigo, which is also a dye. The Indigo that I am using is bound in linseed oil by a company called "Natural Pigments" with their oil paint line "Rublev". This indigo is labeled as "Maya Blue" because the indigo dye is on a base of palygorskite clay, this factor could produce different results than plain indigo might produce- this one is perhaps more stable.
Here is my sample of Tyrian Purple that I acquired through Kremer Pigments. While Tyrian Purple is commercially readily available, it is only for those who can afford it. This small sample of Tyrian Purple that I have cost me $107 USD + shipping. This hefty sum for a mere 25mg of powder. Tyrian Purple is easily the most expensive pigment in the world, Vantablack may be up there as well if it were ever commercially available. Tyrian Purple easily takes the cake, however.
Ok, so now that I have given a brief history on how Tyrian Purple is made, what it is, its historical usage, and my outline for what my research will entail- I will now share the results of my research with you.
1st Test- Reactivity
5/9/17 - 8/1/17
Going into this test I suspected that none of the 3 pigments in question would be reactive with sulfur, and I was right. Generally, the only pigments that you can count on being reactive with sulfur bearing pigments are heavy metals such as copper, arsenic, and lead. This test is time based, as I generally give 1-3 months to wait and see if a recation occurs between the pigment in question vs. the sulfur bearing pigment.
CONCLUSION- Not reactive.
2nd Test- Lightfastness
5/9/17 - 8/1/17
This test is always the juiciest and most anticipated test out of all of them, and for good reason. Lightfastness tells us how well the color will hold up over time given exposure to UV light. So what I have found here is that both Dioxazine Purple and Indigo have held up well. This is a time-based test, I usually allow 3 months of direct sun exposure to see how much/ if at all a color will fade or change in appearance. The Indigo here is on a base of palygorskite clay, so this may have influenced its stability here, as indigo is generally less lightfast. Tyrian Purple bound within oil is without a doubt not lightfast. If you look at the "in" sample vs the "out" sample [indoor vs outdoor] the indoor sample has retained some of its color, whereas the sun exposed sample has had its saturation completely obliterated. I had to photograph these test strips personally because my scanner wasn't depicting the differences adequately.
CONCLUSION- Not lightfast.
3rd Test- Transparency
With this test here you can see that I have mixed all 3 colors- Dioxazine Purple, Indigo, and Tyrian purple with Lead white and Bone black. I have also taken a small amount of Tyrian Purple and glazed it over lead white. According to the glaze and the mixing with black and white, I would have to say that Tyrian Purple is a weak tinter and is transparent. I am skeptical to see how much the data would differ had I had a larger sample of Tyrian Purple to work form for my testing. I think however that it would still lean on the transparent and weak tinter side.
CONCLUSION- Transparent? [data is limited]
4th Test- Permanency
LEFT- 5/9/17 [aged almost 3 months]
RIGHT- 8/1/17 [fresh]
As you can see Tyrian Purple itself shifts in hue on its own with out direct exposure to sunlight, for this reason, I cannot call it permanent. It shifts rather quickly as well. Within the course of a few days to a week the color shifts to a warmer, less saturated violet color. Granted the fresh sample of Tyrian contains a little more pigment, it is very obvious that it has lost saturation.
CONCLUSION- Not permanent.
5th Test- Pigment In Practice
I have thoroughly enjoyed researching Tyrian Purple, one pigment that I place in a handful of other extraordinary pigments that I am glad that I got to test in the realm of oil painting. Now that I have tested Emerald Green, Mummy Brown [reproduction], and Tyrian Purple I have my eyes on genuine Indian Yellow. Hopefully, this can be a reality!