Why don’t we wear techeiles on our tzitzis today?

The mitzva of tzitzis includes having a woolen “pesil” dyed with techeiles, extracted from chilazon blood. While white fringes alone fulfill the mitzvah, having some dyed with techeiles, when it’s available, contributes to the mitzva’s complete fulfillment. The rishonim debate how many of the eight strings should be dyed: either one string (i.e., half of a folded string), two, or four, and the Alter Rebbe rules like the third view.¹

The Gemara describes the chilazon as a sea creature that would surface once in ⁷⁰ years. Chazal were aware of fraudulent techeiles and outlined tests to distinguish authentic dye from counterfeits like kala ilan, a plant-based indigo dye.²

At some point after Talmudic times, the identity of the chilazon became lost for over a thousand years. In 1887, the Radziner Rebbe, Harav Gershon Leiner, proposed the cuttlefish as the chilazon and wrote extensively to support his theory.³ Many of his contemporaries doubted this assertion, and Harav Yitzchak HaLevi Herzog later demonstrated that the blue tint of the cuttlefish dye came from chemical additives. Instead, Harav Herzog proposed the Murex snail, which produces a purple dye. In 1985, it was discovered that the Murex dye could be transformed into sky blue by exposure to sunlight.

Despite these discoveries, most Yidden continue to wear only white tzitzis. Poskim note problems with the theories and point to the lack of a mesora (unbroken tradition) with no candidate meeting all of the criteria given by Chazal. Using the wrong dye can even invalidate the tzitzis according to some.⁴ (Some explain that safek de’oraysa lechumra is only when, at the end, you will have certainly fulfilled the desired mitzva.⁵)

According to Kabbala, techeiles corresponds to a high spiritual level unattainable during golus. The Arizal taught that techeiles is hidden until Moshiach’s times, and Midrashim echo a similar idea.⁶ In a lengthy letter to the Radziner’s son and successor, the Rebbe Rashab explains this in line with the Alter Rebbe’s maamorim.⁷

The Rebbe writes that we follow the Rebbe Rashab’s words.⁸ Elsewhere, the Rebbe explains that the absence of techeiles in galus demonstrates that the primary avoda must be in the kav of Ahava (represented by the white fringes).⁹

See Sources (open PDF)