The Machon Ptil Tekhelet has (to my mind) some pretty compelling arguments as to why the Murex Trunculus is very likely the genuine chilazon from which techeles (blue dye) for the mitzva of tzitzis is produced.

OTOH, we don't see that the Orthodox Jewish world is collectively rushing out to fulfill the mitzva as prescribed in the Torah. And not for lack of money, either - there is no end of people who are spending extra money on tefillin that are blackened on the back, extra-mehudar esrogim, the most expensive matzos available etc. So why are people not spending extra money to put techeles in their tzitzis?

I speculate a few reasons:

  1. They have not heard of the research and reasoning of Machon Ptil Tekhelet.
  2. They do not accept said research and reasoning and believe it is not the real techeles.
  3. They are unconvinced that it is the real techeles, and therefore don't feel compelled to act - but then why not buy it even out of doubt, when a Torah mitzva is at stake? Or is there some potential loss in the event that Murex Trunculus is not genuine techeles?
  4. The Rabbis accept that it would be good to wear techeles, but they themselves don't want to start wearing techeles publicly, because this will put pressure on the general populace to follow suit, and the expense will be too great for some people; therefore they decided effectively to be mevatel mitzvas aseh (annul a positive commandment) for the sake of shalom/peace, and not place people under additional financial stress.
  5. It's a political thing (I hope not!) - since Machon Ptil Tekhelet is identified with the Dati Leumi (Religious Zionist) sector, the Charedi (black-and-white) world doesn't want anything to do with it.

What are your thoughts?

  • 4
    Duplicate of judaism.stackexchange.com/questions/3479/…. – Alex May 17 '11 at 13:54
  • 2
    It is sort of a duplicate, except with more info in the question. The answers there don't deal with all the issues I've mentioned here, and I'd like to see more discussion on the subject... – Shaul Behr May 17 '11 at 14:03
  • 3
    The late Lubavitcher Rebbe ZYA noted that people didn't seem to make much effort to obtain techeiles even when it was available. He theorised that this was because there is a risk of a issur m'deoraysa when linen clothes have techeiles strings (which must be wool) attached to them: if the strings aren't real techeiles then the garment is shatnez and may not be worn. Consequently, he argues, the use of techeiles may have been discouraged (although not actually forbidden), in a way that parallels the laws against taking a lulav or using a shofar on Shabbat that coincides with a festival. – Joe in Australia May 17 '11 at 16:35
  • 1
    For all the Halachic issues of the Tchelis see this shiur on YU Torah From Rabbi Yisroel Reisman Techeles Hachodosh-The Issues – simchastorah Jul 15 '11 at 3:47
  • 1
    Here are two great links that discuss this extensively: + dafyomi.co.il/menachos/insites/mn-dt-044.htm (read part 2 also) + yeshiva.org.il/midrash/shiur.asp?id=7683 – user1624 Jun 15 '12 at 15:44

13 Answers 13


I think the question is asked backwards. Nothing is "universally accepted" unless you limit the meaning of "universe" to the groups of people you tend to agree with, or think have valid views.

The question to me, is for those who accept the new techelet. Why don't they pressure other Jews to wear them? Or, if offered a communal talit, why would most not say that the talit is not a talit because it doesn't have techelet?

The answer to that might have to do with the personality of people who are more willing to accept the new techelet, or it might be because they also agree that not wearing techelet is ok.

I would argue, that techelet is not "universally" accepted because those who do accept it, are not pushing an effort to make more people accept it. They don't look down upon, or make snide comments to those who have all white tzizit. On the other hand, those who do only wear white tzizit, will often attempt to discourage those who wear techelet. (The guy at my local judaica shop doesn't carry techelet at all, and tried to tell me it was assur min ha gedolim)

  • Maybe they feel that a communal tallit is actually patur from tzitzit; that's why most people don't say a bracha on it. – Double AA Jun 15 '12 at 15:51
  • [T]hose who do accept [techelet], are not pushing an effort to make more people accept it. They don't look down upon, or make snide comments to those who have all white tzizit. On the other hand, those who do only wear white tzizit, will often attempt to discourage those who wear techelet. This is not my experience at all. – Fred Aug 8 '16 at 23:36

Most of those people who don't accept the Machon Ptil Tekhelet's research and reasons do so because they are of the opinion that once a Mesorah has been lost, we can not get it back/reinstate it until Moshiach comes. Incidentally, I believe Rav Kook ZT"L was also of that opinion.

  • This is the reasoning that I've heard given in support of the opinion not to wear techelet. I don't think that the same reason applies to Har Habayit, but what Techelet and Har Habayit have in common is that they represent changes in reality/practice and are therefore rejected by some. – Meir May 18 '11 at 18:06
  • 1
    R' JB Soloveitchik was of this opinion, and R' Aharon Lichtenstein (his son-in-law) doesn't wear Tekheleth "for personal reasons", although R' Herschel Schachter (who effectively bears the Rav's mantle at Yeshiva University and within the modern Orthodox world) does wear it, following Shittath Tosafoth/Rashi (R' Lichtenstein, though he doesn't wear it, advises those who would wear it to follow Shittath RaMBa"M). – Seth J Jun 20 '11 at 19:43
  • Can you source that Rav Kook held this way? His great-nephew, R Simcha Kook, doesn't hold that way. – Double AA May 25 '16 at 4:28
  • If this is true how come 90% of the world says Mezonot on rice? hebrewbooks.org/pdfpager.aspx?req=20025&st=&pgnum=139 – Double AA Nov 1 '16 at 17:22
  • The Maharil clearly didn't accept this וסברא הוא דשמא יחזור דבר לקילקולו שיהא תכלת מצוי, כ"ש למאי דכתב סמ"ג דאותו דג חלזון הוא בים המלח וכתב סימנין, בקל היה לעשות תכלת – Double AA Dec 9 '16 at 1:38

The Gemara (Bava Metzia 61b) speaks pretty harshly about "one who attaches kala ilan [indigo] to his garment and claims that it's techeiles." Since, as Shalom noted, the identity of techeiles is in fact uncertain (I've heard of at least three different opinions what creature it comes from), that may be reason enough to avoid using what might be the wrong stuff.

There is also a Kabbalistic idea (from the Arizal) that techeiles is not needed after the destruction of the Beis Hamikdash, and that it will be restored only when Moshiach comes.

  • 3
    Safek deOraisa implies that you should wear the techeiles so you can fulfill the mitzva. The mishna (hebrewbooks.org/shas.aspx?mesechta=30&daf=38&format=pdf) tells us you are yotze anyway. That brings down the stakes somewhat. – YDK Oct 15 '10 at 14:08
  • 4
    Isaac, the opinion of the Rosh, that wearing any other color in the Tzitzis besides for the Lavan and Ticheiles invalidates the mitzvah could throw the safek di'oraisa in the opposite direction and leave us with shev v'al taaseh just in case it is not really t'cheiles (or the correct shade of t'cheiles.) – Yahu Oct 17 '10 at 4:25
  • 2
    @Alex, to your answer - Except that Kalah Ilan is derived from a plant and is outlawed because it was used to deceived people and sell knock-off Techeileth, not because wearing it in and of itself was problematic. It's not valid, of course, but wearing it was only prohibited as a measure to prevent deceptive sales practices. – Seth J Jun 21 '11 at 15:57
  • 1
    @IsaacMoses Rav Elyashiv in Teshuvot WeHanhagot (1:26) where he brings down an opinion that "Safek Deorayta LeHumra" only applies in a case where you know for sure that you are being Yotze. However, we don't even know 100% percent if we are being Yotze Mitzvas HaTecheles. He actually proves from a Gemara (I believe Rosh HaShana 33a). – Hacham Gabriel Dec 25 '11 at 5:02
  • 1
    @Yahu can you please give me the exact source of that Rosh?? – Hacham Gabriel Dec 25 '11 at 23:30

The Rambam says that using the wrong techelet makes the tzitzit pasul. Additionally, if you don't use techelet at all you fulfill the mitzvah. Simply not a gamble worth taking - it's already a mitzvah in the bank.

Mishna Torah - Hilchot Tzitzit- chapter 2, halacha 1: The term techelet when used regarding tzitzit refers to a specific dye that remains beautiful without changing. [If the techelet] is not dyed with this dye, it is unfit to be used as tzitzit (פסול) even though it is sky blue in color. והתכלת האמורה בציצית, צריך שתהא צביעתה צביעה ידועה, שעומדת ביפיה, ולא תשתנה. וכל שלא נצבע באותה הצביעה, פסול לציצית: אף על פי שהוא כעין הרקיע, כגון שצבעו באסטיס או בשאר המשחירין--הרי זה פסול לציצית. ורחל בת עז, צמרה פסול לציצית

  • 3
    Do you have a source for this? I just listened to the lecture by R' Reisman that simchashatorah linked to, and while R' Reisman is convinced, based on his reading of the gemaras, that Murex Trunculus is not chilazon, he was very clear that coloring some strings with a non-techeilet blue dye would not take away the mitzva of tzitzit. – Isaac Moses Jul 15 '11 at 16:42
  • 1
    Issac, as far as "coloring some strings with a non-techeilet blue dye would not take away the mitzva of tzitzit." The Rambam is also of this opinion as he encourages coloring white tzitzit to match the color of the garment ("If it is green, they should be green. If it is red, they should be red" -halacha 8). However, that only applies to the white strings, he clearly states that using a different techelet is pasul. – zaq Jul 18 '11 at 1:32
  • 6
    I am not so convinced by this. There is a difference between פסול לציצית and פוסל לציצית. Pasul letzitzis means that it is invalid for the purpose of (the techeiles) for tzitzis. Posel letzitzis would mean that it invalidates the whole tzitzis. This is subject to a diyuk in the Rambam, so consult your local Orthodox rabbi. – josh waxman Jan 10 '12 at 17:38
  • @joshwaxman is it necessary to mention being invalid for the purpose of tzitzis if the tzitzis are still valid, regardless? Seems out of place in a halachic code, to me. – Baby Seal Mar 23 '14 at 17:19
  • 2
    The relevance to the halachic code would be that it is invalid for the purpose of techeilet. – josh waxman Mar 23 '14 at 19:00

Two versions of Brisker Ravs response to Radziner Rebbe; one that's recorded in Radziner Rebbe's book is that there must be compelling archeological evidence that the tcheilis is indeed the correct version. Another verison passed down by word of mouth in the Soloveitchik family was that we lost the Mesorah. However, Rav Eliyashuv, in a letter adressed to his Talmid, Rav Feivel Cohen of NY, believed the first version was correct based on Halachic principles. In any event, Rav Eliyashuv wanted to do more research before committing to a specific psak. The Baal Hamaor paskuns in Shabbos 2nd perek that Tcheilis is meakav Halavan. He actually didn't wear Tzitzis!!! Could be that if the Tcheiles is in fact correct we should be obligated. Another consideration is the high peice of Tcheiles that the Rabbonim don't want to obligate the general population to purchase.



Thhe Rebbe Rashab wrote to R' Leiner (The original re-discoverer of techeiles [even though he was found to have been fooled by the scientists of his day, yet the reasons of the Rebbe Rashab still apply to the modern day tcheiles.]).

The Rebbe Rashab writes that it cannot be the real tcheiles because the Alter Rebbe writes in Likkutei Torah (in the name of the Pri Aitz Chaim) that there is no tcheiles in the time of exile because it represents a high spiritual level that we cannot reach in the time of exile.

This is similar to the rule that we do not blow Shofar on Rosh Hashana that falls out on Shabbos because of the Gzeira of Rava (we are afraid one will carry it in the street to learn how to blow it.) However, in Kabbalah it's explained that we don't blow shofar on shabbos because we can't reach the level of Shofar (whatever the shofar would accomplish shabbos already does). It is explained in Chassidus that the real reason for not blowing the shofar is because of the Kabbalistic reason, but in order not to make rulings based on only kabbalah, the gemarah gives a reason (although seemingly forced) of the gzeirah of Rava.

So too here, we can't reach what Tcheiles represents in exile, therefore, we shouldn't wear it, and the simple reason is because people may put it on a linen garment (tzitzis with tcheichles (wool) can be put on a linen garment) but we are not sure that it is real tcheiles, so we don't wear tcheiles at all.

The Rebbe Rashabs also asks that if the only reason nobody wore tcheiles was because of expenses, why were there no exceptionally pious people who would try to get a hold of it at all costs, like people tried getting Esrogim at all costs even when there were wars, etc.

  • I do not understand the "people may put it on a linen garment" argument. Does this not apply equally to a tzitzis without t'cheles such that people should not put them on at all for fear of attaching wool strings to linen garments? – WAF Jul 6 '11 at 22:02
  • I didn't write this- this is from Mois Navon, so don't blame me. Also, I don't agree with this explaining explaining and neither do most Mekubalim. (Exact quote from Mois Navon) "The Arizal states, “For the truth is that at this time, after the destruction of the Temple, we don’t have the power to wear tekhelet” (Pri Etz Hayim, Shaar HaTzitzit, ch. 5). The Lubavitcher Rebbi (Rashab), though he held the Ari’s word to imply that we do not wear tekhelet now, nevertheless writes, “the mitzvah is an eternal one, and when we will be able to fulfill it, so we must do.” – Hacham Gabriel Dec 21 '11 at 3:44
  • 2
    So he's just making up a Gezera out of thin air? – Double AA Jan 18 '15 at 23:36
  • 1
    there is no tcheiles in the time of exile One should always be wary of ruling based on a mistake. The evidence shows that even Ammoraim had tekhelet. – mevaqesh Sep 29 '16 at 21:42

They have some good evidence but there are also some issues. For example, why doesn't any earlier source mention that Techelet is from the same thing as Aragaman? It seems like a pretty basic thing that they should say when identifying the animal.

Another problem is how the Gemara's test (to make sure it wasn't indigo) would work if Techelet is chemically identical to indigo. The institute says there were impurities or something involved in the process, but its still an issue.

Also, (as of a year ago) they have not showed how the Techelet would have been extracted in ancient times. This would be an important way to demonstrate its real. (They use modern techniques to get it.)

A fourth issue was raise more recently by researchers that claimed techelet was really a different color. That would also have to be dealt with.

If they can answer these objections, I think more people will begin wearing it, though not necessarily haredim.

Update: They have now shown how the extraction and dying process could have been done in ancient times. There's also a large amount of evidence that those snails were used for dying then.

  • You mean the other way around. The "Kippa Srugah" crowd - especially those in Israel - wear it. The Charedim do not, other than certain Chassidim who use that of the Radzyner Rebbe, which across the board is rejected as not being the same as what was in the Mesorah. Charedim will not wear Techelet because of what I said before. That and the science won't matter to them anyway because it's the Mesorah that counts, not the scientific research. – Zvi May 18 '11 at 3:29
  • I edited it. Most people in America (and Israel, from what I saw) do not yet wear techelet. If more evidence was brought, I think more rabbonim would support it, and it would likely catch on. But many haredim would likely still not accept it. – Ariel K May 18 '11 at 4:50
  • "Also, (as of a year ago) they have not showed how the Techelet would have been extracted in ancient times. This would be an important way to demonstrate its real. (They use modern techniques to get it.)" If you're referring to the dyeing/coloring process, this is not correct. IIRC, they demonstrate that lengthy sun exposure gives it its color and forces the bonding, though the chemicals they use complete this process more quickly. If you're referring to the physical extraction of the ink from the snail, I can't find information on this. – Seth J Jun 20 '11 at 19:56
  • I think this link is relevant (I don't know why they didn't refer to Rav Sherlow with the title of "Rabbi"): nytimes.com/2011/02/28/world/middleeast/28blue.html – Zvi Jun 22 '11 at 4:41

Many believe that once the mesora (tradition) was lost, it was lost; modern scientific methods can't restore mesora. (The fact that there are different forms of tcheiles today doesn't help.)

  • 1
    I believe this is the approach of R' Chaim Soloveitchik (or perhaps the Beis HaLevi or the Brisker Rav, I don't recall). – Dave Oct 31 '10 at 20:05

For Ashkenazim I still can't find an answer to this Taana- Safek Deorayta LeHumra. If you are Ashekenazi then until I hear otherwise I think you should wear Tekhlet. However, for Sephardim this isn't the case because the Techelet will only return at the time of the rebuilding of the bet hamikdash (see ben yohayada b"m 61b).

EDIT: I found an answer from the Rav Sternbuch Shelit"a in Teshuvot WeHanhagot (1:26) where he brings down an opinion that "Safek Deorayta LeHumra" only applies in a case where you know for sure that you are being Yotze. However, we don't even know 100% percent if we are being Yotze Mitzvas HaTecheles.

  • 1
    According to that opinion, one would not need to blow shofar during bein hashemashot, yet we see the Mishna Brura OC 600:7 says to blow out of doubt even though you might not be yotzei anything. Seems like we don't paskin like this opinion. – Double AA Dec 25 '11 at 7:50
  • 1
    But you are agreeing that you should wear them! Safek Deoraita leChumra applies! – Double AA Dec 25 '11 at 15:41
  • 1
    I've never met anyone who says "Al Mitzvat Techelet." The bracha is on the tzitzit. But it doesn't matter: all I'm pointing out is that we do not paskin like the shitta that RYSE quotes. With that in mind we can go decide about techelet, but this shitta is not part of the calculations. – Double AA Dec 25 '11 at 16:01
  • 1
    Not at all: it's not pasul if it's the wrong dye. You just aren't yotzei the separate mitzva of techelet. So worst come to worst you still say a bracha on the tzitzit. The din of the bracha is part of safeik brachot lehakel not the safek deoraita lechumra of the techelet. – Double AA Dec 25 '11 at 19:22
  • 1
    Please do find a source, but realize that kalei ilan could be different from any other false dye, as Chazal were specifically gozer on it. – Double AA Dec 25 '11 at 19:32

from http://doseofhalacha.blogspot.co.uk/2013/02/a-colourful-debate.html

Question: I see some men walking around with a blue techeles thread on their tzitzis. If we know what techeles is, why don’t we all wear it?

Answer: Wearing techeles was always an integral part of the mitzva of wearing tzitzis. Unfortunately, however, the art of making techeles from the chilazon has been lost for close to 2,000 years. The Midrash (Tanchuma, Shelach) laments that “now we have no techeles, only white, as techeles has been hidden.” While the Tosefta (Bava Metzia 61:) writes that one who doesn’t wear techeles has transgressed the mitzva of tzitzis, we see in the Gemara (Bava Metzia 61b and Menachot 40a, 43a) that wearing the wrong techeles invalidates the tzitzis.

But what is the chilazon? In the 1880’s, the Radzyner Rebbe, R’ Gershon Henoch Leiner, maintained that a particular squid (Sepia officinalis) was the long lost chilazon. He published 3 seforim on the subject, though while many used this dye to make techeles, it was far from blue and white! In 1913, R’ Issac Herzog published his doctoral thesis on techeles, naming a mollusk (Murex trunculus) as the most likely candidate for the source of techeles. The debate continues to this day.

While R’ Herzog’s arguments are most compelling, the Beis Halevi (R’ Yosef Ber Soloveitchik, 1820-1892) maintained that as the techeles has been lost from our mesorah, tradition, it should not be reinstated, irrespective of the evidence. It is certainly no simple matter to reinstate a ‘lost tradition:’

While Kohanim duchen daily (Birchas Kohanim) in Eretz Yisrael, in Chutz La’aretz this Mitzva is reserved for Yom Tov. Various reasons have been given for this, including our lack of true Simcha in the Diaspora. Nonetheless, many Gedolim including both the Vilna Gaon and his student, R’ Chaim of Volozhin unsuccessfully tried to reinstate the daily Bracha. The Aruch Hashulchan (OC 128:64) writes that it’s as if there was a voice from heaven calling out against reinstating it.

We eagerly await the day when the true glory of these Mitzvos will be reinstated for all.

  • Since when do we care about voices from heaven? Lo bashamayim hi. – Double AA Mar 23 '14 at 12:41

This answer may have been hinted to but I don't think it was mainstream enough. The reason we don't wear Tekhelet is because the GEDOLEI TORAH don't and we trust they know their business.


I have two hypotheses:

1) If a major rav were to come out with a clear psak in favor, or just start wearing techelet publicly himself, it would be a whole lot to carry on his shoulders. As far as I know, most poskim are hesitant to tackle the question at all. Even Rav Moshe Karp was staunchly opposed to wearing techelet, but when one of his sons came home one Shabbos with techelet (so the story goes) he had no alternative, and started debating techelet proponents. Eventually he changed his opinion. I'm not sure exactly what he holds today.

2) A lot of charedim are very hesitant to go against the grain, therefore they are not prepared to be open-minded in approaching the question. From my observations, I get the impression that they will grasp at the first argument they hear against it, and breathe a sigh of relief that now they won't have to stick out like a sore thumb. But I've almost never come across someone charedi who decides to investigate the topic very open-mindedly and then comes to the conclusion that he should not wear Murex trunculus.

  • When I was in J'lem over the summer near Mea Shearim, I saw many chareidim (mostly chassidim, if my assessment of their levush was correct) wearing techeilet. I was quite surprised, but I have seen the Techeiles Chabura website, so it seems less clearcut from that. – Noach MiFrankfurt Dec 1 '15 at 20:31

Parshas Shelach discusses Techeiles at the very end and Rashi (14:41) says on the pasuk "Ani Hashem" which means that "I am the one who in the future with discern and exact payment from one who puts a turquoise dye extracted from a tree on his garment and says its Techeiles. His source is found in Bava Metzia 61B which commentators mention there that an unscrupulous person would dye his tzitzis not knowing this makes the mitzvah of tzitzis pasul and then tries to sell them in the market place.

  • How does this relate to the question? – Shaul Behr Jun 18 '12 at 10:45
  • @Shaul Rashi is pointing out that even during the times that the mesorah of Techeiles existed, it was still something rare that not everyone wore and unscrupulous merchants would sell the tree dye blue fringes and claim they are techeiles. Since no widely accepted hecksher today is willing to put their seal on this, is reason enough to not purchase and wear it. – user1292 Jun 18 '12 at 16:05
  • I believe the accepted answer judaism.stackexchange.com/a/8853/159 addresses your approach directly. – Shaul Behr Jun 19 '12 at 7:45
  • @Shaul Please help me understand because I do not see the connection. We have 3 elements here. 1. Is it Kosher? 2. If it is Kosher is NOT having it Kosher? 3. Which I am addressing is how can we guarantee that the techelis on the tzitzis you are buying is Kosher? We live in a world of hekshurs today just like your tallis has a hekshur and your meat, dairy, etc. So why isn't a mainstream heskhur supporting it? Well it might be a case of element #1. I believe it is important to know that just like in the days of Rashi, and the Gemara that not all merchants are reliable and to be careful. – user1292 Jun 19 '12 at 17:11
  • 2
    This is not the same as kashrus of food, where there's an actual issur to eat neveila, basar b'chalav etc. Kala ilan involves an issur of deception, where someone is tricking someone else into thinking that this is real techeles; here the avaryan is the trickster, not the person who wears the fake techeles - unless they happen to be the same person and the fool thinks he can trick G-d. But if someone has determined, to the best of their ability, that this is "real" techeles, there is at least no loss in wearing it, and possibly an aseh d'oraysa to gain. – Shaul Behr Jun 20 '12 at 6:28

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .