Halakhah sobre Menajot 4:6

Even if we could locate Kohanim with the necessary lineage, they still may not offer korbanot without wearing the bigdei kehunah, the priestly garments (Zevachim 15b). Several of these garments require wool dyed with techeilet (see Shemot Chapter 28), or else they are unacceptable.¹²Some debate exists regarding precisely which garments need techeilet; see Rambam (Hilchot Klei Hamikdash 8:1) and Ir Hakodesh V’hamikdash (5:5). We also do not know the identities of two other dyes, tola’at shani and argaman, which the Torah also requires for the bigdei kehunah. Techeilet, a shade of blue (see Menachot 43b), comes from a creature known as the chilazon,¹³See Rambam, Hilchot Tzitzit 2:1-2, and compare with Hilchot Klei Hamikdash 8:13. The Mirkevet Hamishneh (Hilchot Tzitzit 2:1) notes that the Rambam mentions the chilazon only regarding tzitzit. Accordingly, he suggests that the Rambam would permit dying the bigdei kehunah with any blue dye (including dyes that fade), and not only the “blood” of the chilazon.
The Tiferet Yisrael (Kupat Harochlim, Klalei Bigdei Kodesh Shel Kehunah; printed as an introduction to Seder Mo’eid) goes even further, arguing that even tzitzit do not actually require the chilazon’s “blood,” but rather can be made of any permanent (non-fading) blue dye (also see Drishat Tzion, Ma’amar Kadishin 3). He explains that the Gemara often contrasts the chilazon with a plant dye called kaleh ha’ilan because kaleh ha’ilan is the only dye that cannot be used for techeilet. Most authorities do not appear to accept the views of the Mirkevet Hamishneh and Tiferet Yisrael (see Mishneh Lamelech, Hilchot Klei Hamikdash 8:11, and Mishkan Shiloh p. 407). Indeed, Rav Yosef Dov Soloveitchik told me he believes that the bigdei kehunah are invalid without proper techeilet. which we have not used for centuries (see Rambam’s commentary to the Mishnah, Menachot 4:1). Great efforts have been made in recent years, however, to identify the chilazon as the Murex Trunculus snail (see Techumin 9:423-446). Dye from this snail has now been made available for use in tzitzit and could theoretically be used to dye bigdei kehunah. Although some prominent rabbis (such as Rav Hershel Schachter) treat many of the arguments for the use of the Murex Trunculus seriously, only time will tell if the observant community will widely accept this dye as authentic techeilet.¹⁴See Tekhelet: The Renaissance of a Mitzvah for essays by several Rashei Yeshiva of Yeshiva University regarding the use of techeilet from the Murex Trunculus in tzitzit. Rav Schachter, in his essay, describes the Murex Trunculus as safeik techeilet (possible techeilet). Also see Kovetz Teshuvot 2, where Rav Yosef Shalom Eliashiv rejects the use of the new techeilet.

In the early 1990s, Rav Eliyahu Tavger¹¹Rav Tavger was assisted by Dr. Ari Greenspan, Dr. Baruch Sterman, and Mr. Joel Guberman. (see Techumin 9:425-428) sought to demonstrate that the murex trunculus (a type of snail) is the chilazon, the crustacean whose blood must be used to create the techeilet dye for tzitzit.¹²Some of the tzitzit strings are supposed to be dyed with techeilet, but the Mishnah (Menachot 4:1) states that we fulfill some aspects of the mitzvah even if we do not have this dye, which has been the case for at least one thousand years. Among Rav Tavger’s proofs are archaeological finds on the northern coast of Eretz Yisrael, where huge mounds of murex trunculus shells were discovered alongside dyeing vats (Encyclopedia Judaica 15:914). His claim sparked a great controversy, as some believed it likely that a mitzvah that had been lost from Am Yisrael for over one thousand years¹³For a discussion of when precisely the use of techeilet ceased, see Rav Tavger’s essay on this topic published in Kuntreis - Topics in Tekhelet, 5767 (available at www.tekhelet.com). He reviews the debate between the Radzyner Rebbe and Rav Yitzchak Herzog regarding whether techeilet was used during the times of the Geonim. finally had been restored, while others doubted this claim. This controversy still has not been resolved, leading some Jews to wear tzitzit dyed with this “new” techeilet and others to refrain.