Shellfish purple dye

We examined first the archaeological materials for dyestuflF identification at the request of Junius Bird of the American Museum of Natural History on behalf of Peter Gerhard who was studying the distribution of the shellfish purple dye. This dye is believed to have been used in ancient times in Central and South America and in Mexico and is still in use on the west coast of Mexico. The results of his work have been published 11), and we will confine our comments to the analytical... 

Figure 2, Known shellfish purple dye solutions compared with those obtained...

Figure 4. H SO (cone,) solutions of indigo (----) and shellfish (----) purple dye...

It is one thing to discover a coloured substance but its attachment, in a fast or permanent condition, to a fabric is a different and often difficult matter. That the ancient dyers had attained a complete mastery of the art of dyeing with Tyrian Purple is clear from the assertion of Lucretius in De Rerum Jiaiura The purple dye of the shellfish so unites with the body of wool alone, that it cannot in any case be severed, not were you to take pains to undo what is done with Neptune s wave, not if the whole sea were willed to wash it out with all its waters. ... 

On the other hand, the almost colorless fluid secreted by Murex brandaris, a shellfish of the Mediterranean Sea region, becomes reddish purple on contact with air. The fluid was used by the Phoenicians as a dye from about 1500 BC, and the purple dye is known as Tyrian purple, ancient purple, or shellfish purple, etc. Friedlander, in 1915, isolated about 1.5 g of the pigment from 12,000 specimens of M. brandaris, and clarified its chemical structure as 6,6 -dibromoindigo [5]. Subsequently, the origin of this pigment was identified as sodium tyrindoxyl sulfate [6]. 

Textile dyes were, until the nineteenth century invention of aniline dyes, derived from biological sources plants or animals, eg, insects or, as in the case of the highly prized classical dyestuff Tyrian purple, a shellfish. Some of these natural dyes are so-caUed vat dyes, eg, indigo and Tyrian purple, in which a chemical modification after binding to the fiber results in the intended color. Some others are direct dyes, eg, walnut sheU and safflower, that can be apphed directly to the fiber. The majority, however, are mordant dyes a metal salt precipitated onto the fiber facUitates the binding of the dyestuff Aluminum, iron, and tin salts ate the most common historical mordants. The color of the dyed textile depends on the mordant used for example, cochineal is crimson when mordanted with aluminum, purple with iron, and scarlet with tin (see Dyes AND DYE INTERMEDIATES). 

The chemistry of colorants, particularly in the dyeing of textiles, has a long and rich history. There are indications that the art of dyeing was practiced as early as 3000 B.C.E. in China and Egypt [21]. The colorants used were obtained from natural sources. Examples include blue indigo from the indigo plant, reds fi om the root of madder, yellows and reds from saffiower, and lyrian Purple produced by the Phoenicians from shellfish [22]. 

Tyrian Purple the most expensive dye (main component is dibromo indigo), historically also called royal purple, is obtained from purpura shellfish Murex brandaris) and is substituted by synthetic dye today (12000 mollusks were necessary to obtain 1.4 g of the dye). 

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