Tyrian purple the Iles Purpuraires at Mogador, in Morocco. The sea snail harvested at this western Moroccan dye production facility was "Hexaplex trunculus" (mentioned above) also known by the older name "Murex trunculus". This second species of dye murex is found today on the Mediterranean and Atlantic coasts of Europe and Africa (Spain and Portugal, Morocco, and the Canary Islands). The colour-fast (non-fading) dye was an item of luxury trade, prized by Romans, who used it to colour ceremonial robes. Used as a dye, the color shifts from blue (peak absorption at 590 nm, which is yellow-orange) to reddish-purple (peak absorption at
Sulfur dye rubbing. The dyes are bleached by hypochlorite bleach. Due to the highly polluting nature of the dye-bath effluent, sulfur dyes are being slowly phased out in the West but they are used on a large scale in China. Recent advances in dyeing technologies have allowed the substitution of toxic sulfide reducing agents. Glucose in basic solution is now used and both low sulfide and zero sulfide products are available. Future developments in the field of reducing dye levels by means of electro-chemical processes are promising. Sulfur dye Sulfur dyes are the most commonly used dyes manufactured for cotton in terms