Tekhelet

A set of tzitzit with blue tekhelet thread

Tekhelet, (תכלת), Techelet or Techeiles is a blue dye mentioned 48 times in the Jewish Bible (Tanakh) and translated by the Septuagint as iakinthos (blue). Its uses include the clothing of the High Priest, the tapestries in the Mishkan, and the tassels (known as Tzitzit) to be affixed to the corners of one's garments. Following the destruction of the Temple by the Romans, the sole use of the blue dyed strings was in the tzitzit. Tzitzit are tassels composed of 4 strings for which there are three opinions today as to how many are to be blue: 2 strings (Tosafot, Rashi); 1 string (Raavad); Half String (Rambam).

The Talmud teaches that the source for the blue dye is a marine creature known as the "hillazon" - translated as "snail" in Modern Hebrew. The Talmud also mentions a counterfeit dye from a plant called Kela-Ilan, known as Indigoferra tinctoria, the ubiquitous source of blue dye in the ancient world. The Talmud explains that it is absolutely forbidden to use this counterfeit dye intentionally (i.e., if one was duped, the strings are still kosher, however they simply do not fulfill the religious requirement for tekhelet strings). The Tosefta explains that Kela Ilan is not the only invalid dye source, but in fact everything but the chillazon is unacceptable for making the blue dye.

At some point following the Roman exile of the Jews from the land of Israel, the source of the dye was lost and as a result the Jews have worn only plain white tassles.

The stripes on prayer shawls, often black, but also blue or purple, are believed to symbolize the lost tekhelet which is referred to by various sources as being "black as midnight", "blue as the midday sky", and even purple. Interestingly, these stripes of tekhelet inspired the design of the flag of Israel.

Over the last two centuries, attempts have been made to identify the ancient source of the dye by comparing Talmudic sources to physical evidence. Three types of mollusks have been proposed as the lost "chillazon". None have been universally accepted, though the Murex, Murex trunculus, known by the modern name Hexaplex trunculus is thought to be the most likely source of the biblical blue dye. Most Haredim continue to wear only white tzitziot, following their poskim (decisors of Jewish law).

Chilazon in the Talmud

In the Talmud, (Tractate Menchot 44a, the chilazon is described as follows::

1. Its body is like the sea.
2. Its creation is like a fish.
3. It comes up once in 70 years,
4. Its "blood" is used for tekhelet,
5. Therefore: It is expensive.

Other criteria (with Talmudic references):

• The fishers of the chilazon are from Haifa to Tyre (Shabbat 26a)
• The color of the chilazon dye is identical to that produced from the dye of the kela ilan plant (Indigoferra tinctoria), which served as a counterfeit source of the dye (Baba Metzia 61b)
• Cracking open the shell of the chilazon on Shabbat violates the laws of Shabbat (Shabbat 75a)
• The shell of the chilazon grows together with it (Midrash Shir haShirim Rabbah 4:11)
• The chilazon buries itself in the sand (Megila 6a)
• It is an invertebrate (Yerushalmi Sabbath 1:3 8a)

Sepia officinalis

The common cuttlefish.

A sample of Prussian blue.

In 1887 Rabbi Gershon Henoch Leiner, the Radzyner Rebbe, researched the subject and concluded that the Sepia officinalis (common cuttlefish) met many of the criteria. Within a year, Radziner Hasidim began wearing tzitzit dyed with a colorant produced from this mollusk. The Breslov Hasidim also adopted this custom due to Rebbi Nachman's pronouncement on the great importance of wearing tekhelet.

Rav Herzog obtained a sample of this dye and had it chemically analyzed. The chemists concluded that it was a well-known synthetic dye "Prussian blue" whose color is produced from iron filings, with the cuttlefish merely supplying nitrogen which could have as easily been supplied from a vast array of organic sources (e.g., ox blood). R. Herzog thus rejected the cuttlefish as the chilazon and some suggest that had the Radzyner Rebbe known this fact, he too would have rejected it based on his explicit criterion that the blue color must come from the animal and that all other additives are permitted solely to aid the color in adhering to the wool (P'til Tekhelet, p.168).

Janthina

Within his doctoral research on the subject tekhelet, Rav Herzog, placed great hopes on demonstrating that the Murex trunculus was the genuine "Chillazon". However, having failed to consistently achieve blue dye from the Murex trunculus, he wrote: “If for the present all hope is to be abandoned of rediscovering the hillazon shel tekhelet in some species of the genera Murex and Purpura we could do worse than suggest the Janthina as a not improbable identification” (Herzog, p.71). Though blue dye has indeed been obtained from the Murex t. snail, in 2002 Dr. S.W. Kaplan of Rehovot, Israel proclaimed that he was able to dye wool with the extract of Janthina.

(Dr. Kaplan was contacted and was unable to supply any of the blue wool he allegedly extracted from the Janthina.)

Murex trunculus

A guide from P'til Tekhelet shows how a piece of wool, dipped into the solution for the dye, turns blue in sunlight.

The Murex trunculus, a sea snail, is popularly advanced as the source of the coveted dye. Rabbi Yitzhak HaLevi Herzog (1889-1959) wrote his doctoral thesis in 1913 on the subject and named the Murex snail as the most likely candidate for the dye's source. Though the Murex fulfilled many of the Talmudic criteria, his inability to consistently obtain blue dye (sometimes the dye was purple) from the snail precluded him from proclaiming that dye source had been found.

In the 1980s, Otto Elsner, a chemist from the Shenkar College of Fibers in Israel discovered that if a solution of the dye was exposed to sunlight, blue instead of purple was consistently produced. Eventually, in 1993, the Ptil Tekhelet Foundation was formed for mass production of Murex trunculus tekhelet, as well as to continue further research.