Is the ancient tekhelet dye bluish-purple?

An interesting New York Times article was published today about the ancient Biblical dye known as tekhelet.

One of the mysteries that scholars have puzzled over for centuries is the exact shade of blue represented by “tekhelet,” which the Bible mentions as the color of ceremonial robes donned by high priests and ritual prayer tassels worn by the common Israelite.

What was known about tekhelet (pronounced t-CHELL-et) was that the Talmud said it was produced from the secretion of the sea snail, which is still found on Israeli beaches.

Traditional interpretations have characterized tekhelet as a pure blue, symbolic of the heavens so that Jews would remember God. Not so, according to an Israeli scholar who has a new analysis: tekhelet appears to have been closer to a bluish purple.

The scholar, Zvi C. Koren, a professor specializing in the analytical chemistry of ancient colorants, says he has identified the first known physical sample of tekhelet in a tiny, 2,000-year-old patch of dyed fabric recovered from Masada, King Herod’s Judean Desert fortress, later the site of a mass suicide by Jewish zealots after a long standoff against the Romans.

“It really is majestic,” Dr. Koren said of the shade, which he said remained close to its original hue and appeared to be indigo.

Dr. Koren is scheduled to deliver a paper on Monday at a conference here at Shenkar College of Engineering and Design, where he heads the Edelstein Center for Analysis of Ancient Artifacts.

Dr. Koren, originally from Staten Island, described his work as “Indiana Jones meets C.S.I.” He said that when he first photographed the fabric scrap with the tekhelet dye, “the L.C.D. on my camera literally radiated.”

Until now, the limited number of blue or purple dyes found on textiles from the period in this region have been derived from plant material, he said.

The fabric he examined was one of many items discovered at Masada in the 1960s and stored at Hebrew University in Jerusalem. It came to his attention when a British historian, Hero Granger-Taylor, who specializes in ancient weaves, asked him to analyze some textiles. Dr. Koren said he was the first researcher to make the connection between the fabric and the snail dye.

He found that the dye used in the Masada sample, a piece of bluish-purple yarn embroidery, came from a breed of Murex trunculus snail familiar to modern Israelis. Such shades on textiles are rare finds since they were typically worn exclusively by royalty or nobility.

But the article does not quite explain everything. Today there are people who are producing tekhelet from that same murex trunculus snail, but the dye they are producing is more sky-blue than dark blue/purple. To understand this, one must go to the Tekhelet website:

While researching the methods used by the ancient dyers, Prof. Otto Elsner, of the Shenkar College of Fibers, noticed that on cloudy days, trunculus dye tended towards purple, but on sunny days it was a brilliant blue! He found that at a certain stage of the dyeing process, exposure to sunlight will alter the dye, changing its color from purple to blue.

So if Dr. Koren is correct, the dye must be shielded from the sun in order to produce the correct, darker shade of blue.

The NYT does interview the people who make tekhelet nowadays, and now the rest of the article makes sense:

Baruch Sterman, a P’til Tekhelet founder, said that new scientific findings were unlikely to change the tradition his group had reintroduced: using the sky-blue color for ritual tassels.

“Probably in ancient times, what was most important to the Jews was that the color is a beautiful color and it comes from the snail,” Mr. Sterman said. “The minor distinction — sky blue, turquoise, lapis or purple blue — were probably not of significance to them.”

But then the Times ends off the article with a ridiculous quote, from someone not involved in the entire enterprise and that was almost certainly taken out of context:

Yuval Sherlow, a prominent rabbi in Israel’s modern Orthodox circles — where wearing tekhelet in ritual fringes has become increasingly popular, as it has in American ones — agreed.

“Tradition is not so interested in science,” Mr. Sherlow said. “There is a type of denial of science and new information.”

Since it is modern science that allowed Jews to rediscover which snail was used to create the tekhelet dye, and those who use it today are relying on that same science, the Sherlow quote seems to have been included simply for the Times to bash traditional Jews.