Title: The Dyeing with Murex Extracts, an Unusual Dyeing Method of Wool to the Biblical Sky Blue
Author: Otto Elsner and Ehud Spanier
Journal: Proceedings of the 7th International Wool Textile Research Conference, Tokyo, 1985 Vol. V
In this seminal article, Professors Elsner and Spanier describe the results of their research into the photochemical properties of murex dye. By exposing the vat to sunlight in its reduced state, the purple dibromoindigo is transformed to sky-blue indigo. This discovery resolved the key problem in associating the Murex trunculus with the Talmud’s Hillazon, namely that the snail had yielded only purple, but tradition had maintained that tekhelet was blue.