Mostly everyone agrees that the organization Ptil Tekhelet most likely uses the real techeiles and that Radzyner techeiles is unfortunately not the real deal.

But I'm asking what are the arguments promoting and for Radzyner techeiles?

Also, what disproves Radyzner techeiles other than archaeological finds? Halachah and archaeology don't technically agree on things.

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    Regarding last sentence, why do you assume that archeological evidence is not acceptable here? Do you have an example of a question you feel is comparable in which scientific evidence is not considered halakhically admissible?
    – mevaqesh
    Commented Aug 8, 2016 at 23:49
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    I repeat: Do you have an example of a question you feel is comparable in which scientific evidence is not considered halakhically admissible? (dearth of evidence is not evidence of dearth).
    – mevaqesh
    Commented Aug 8, 2016 at 23:57
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    You say in your title you seek arguments for, but then you seek arguments against
    – Double AA
    Commented Aug 9, 2016 at 0:02
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    Mostly everyone agrees that the organization Ptil Tekhelet most likely uses the real techeiles Umm, not really... Commented Aug 9, 2016 at 11:56
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    @Salmononius2 Ummm... really. Just for whatever reason many think they shouldn't use it anyway. Very few really reject it or think it's not most likely.
    – Double AA
    Commented Aug 9, 2016 at 18:12

5 Answers 5


The Radzyner Rebbe wrote three books about it, so that would be a good place to check.

Dr. Mendel Singer wrote an article about techelet, and in the course of the article, he mentions how the Radzyner Rebbe understood various sources in Chazal to refer to the cuttlefish. For example:

the requirement of once in 70 years, the Radzyner Rebbe says this means that there are times when the chilazon is abundant.

And presumably there are times when the cuttlefish is abundant.

Hidden in the sand: The Gemara in Megilah states that the verse in Devarim 33:19, "sefunei temunei chol" ("hidden treasures of the sand"), refers to the chilazon shel techeilet... On the other hand, it might mean that it is hidden because it is buried in the sand. This is the understanding of the Radzyner Rebbe, citing the Sefer HaKaneh (Hilchot Tzitzit) as stating that the chilazon buries itself in sand with its head sticking out.

And the cuttlefish buries itself in the sand.

Color of the blood: Rambam states that the "blood" of the chilazon shel techeilet is black like ink".[46] Rashi states that the appearance of the "blood" of the chilazon shel techeilet is like the color of techeilet.[47] The Radzyner Rebbe reconciles the apparent contradiction between Rashi and Rambam by explaining that when Rashi says maris damo, "appearance of its blood", he is referring to the "blood" after it is prepared for dyeing, while Rambam refers to the original color of the "blood".[48]

And this is presumably true of the cuttlefish.

Treatment for hemorrhoids: The Gemara also tells us that the chilazon was used to treat hemorrhoids.... Additionally, the Radzyner Rebbe had already written that cuttlefish ink has been used as a treatment for hemorrhoids since ancient times.[52] Indeed, it is still sold today for this purpose.[53]

So the cuttlefish is a good match.

Tentacles bent like hooks: The Mishnah describes a chain hanging on the wall, with something called a chilazon attached to the head of the chain.[55] The mefarshim say it was called this because it was shaped like the chilazon shel techeilet[56], and Tiferes Yisroel explicitly states that this was an iron hook attached at the end which was used to hang the chain on a wall. The Radzyner Rebbe understands this to mean the chilazon has long tentacles that are bent like hooks.[57]

Which apparently would match the cuttlefish.

The biggest problem, which disproves cuttlefish, is not archaeological. It is that its dye is not blue. And the Radzyner Rebbe was misled by an unscrupulous chemist. Basically, he asked this chemist to take cuttlefish ink and make it into a non-fading blue dye. And the chemist accomplished this by a process which basically broke down the molecules of the original organic material (via high temperatures) to the constituent atoms and added iron filings which combined with it, leading to ferric ferrocyanide, or Prussian blue. Start with ANY organic material (with carbon and nitrogen; for instance, human cells) and subject it to the process and you will end up with the same Prussian blue. So it is not coming from the cuttlefish specifically. So if this is the source and the process, why specifically the chilazon?


In 1913, Rabbi Isaac Herzog, then Chief Rabbi of Dublin and later the first Chief Rabbi of the State of Israel, as part of research towards his doctoral thesis, sent samples of the Radzyn tekhelet to leading chemists and dye experts in Germany, France and England for analysis. The results that he received were surprising. The experts determined that the blue dye of Radzyn was not organic in nature, but rather was the inorganic dye known as Prussian Blue, or ferric ferrocyanide. Herzog refused to believe that the Radzyner Rebbe would have purposely misled his followers and wrote to the dye masters of Radzyn asking for their process. Upon investigation, the solution to the riddle became apparent. The Radzyn recipe called for heating the squid ink to very high temperatures and then for the addition of iron filings. What in fact happens under these conditions is that the organic molecules break down and the constituent atoms of carbon and nitrogen recombine with the iron, yielding Prussian Blue dye. The squid ink is not an essential component for this reaction; any organic substance could be substituted, since the structure of the molecule is irrelevant and only the elemental components are utilized. Herzog could not accept the notion that the Talmudic requirement for a specific marine source, the hillazon, could be based on such an indirect and vague relationship. He therefore concluded that the Radzyn tekhelet could not be considered authentic.[52]

  • +1 but there is no in conclusion argument because prussian blue is not from Chilazon and the Radziner was not know this detail
    – kouty
    Commented Aug 9, 2016 at 4:55

There is an interesting documentary regarding the legitimacy of the Radzin Techeiles v.s. the Murex techeles presented by R' Michael Shlomo Bar-Ron. He is a strong supporter of the Radzin Techeiles being authentic. His presentation can be seen here.

Additionally if you are interested in looking at arguments against the Murex as being the Chilazon. Rav Shlomo Miller has a Teshuva (with a write up by Dr. Mendel Singer) against the idea that the Murex is the Chilazon which Chazal spoke of.

Hope this can be helpful.

  • His wearing of a tallis while on a laptop is a little chessy, but it's a good video and resource!
    – ezra
    Commented Aug 9, 2016 at 17:46
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    I was excited to watch that link, until the first few minutes when he lied about which is more popular and called anyone who disagreed with him closed minded, ignorant and lying. Seems like a waste of time now. I'm quite disappointed.
    – Double AA
    Commented Aug 9, 2016 at 18:01
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    @EzraHoerster you should also look at what the Murex people has to say so as to have some "Yishuv HaDaas" when making a decision like this. Commented Sep 6, 2016 at 16:06
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    Your second paragraph doesn't answer the question and should probably be edited out.
    – Double AA
    Commented Oct 28, 2016 at 14:16
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    The question was for arguments. The answer provides no arguments; just a link to them. As such, this is a link only answer.
    – mevaqesh
    Commented Nov 4, 2016 at 6:45

There is a great series online at Torahanytime.com by Rabbi Daniel Glatstein specifically on this topic and I believe you might find what you are looking for there. Even though ultimately the series concludes contrary to that Tehelet being the "official" tehelet: series 1 >> series 2 >> series 3 >> series 4 >> series 5 >> series 6.

  • He doesn't give any arguments for the cuttlefish
    – robev
    Commented Nov 20, 2021 at 19:13

Radzyner Arguments for:

This is an hour long video by Michael Shelomo Bar Ron who brings 8 topics the Ptil Tekhelet organization claims, and attempts to disprove them.

This is the current Radzyner Rebbe's attempt to legitimize the cuttlefish techeiles.

  • The Naked Archeologist (2 part series) on:

True Blue: https://tubitv.com/tv-shows/285717/true_blue

Return of the Halazon: https://tubitv.com/tv-shows/285718/return_of_the_halazon

In both, Simcha Jacobovici researches the blue Techeiles color, in which where there are conversations with both Ptil Tekhelet and the Radzyn Kollel Chabura. The Radzyn Chabura basically state that the source of blue is irrelevant, just as long as the fish is in the mixture. They compare it to Kosher LePesach whiskey and Chametz whiskey, both chemically the same (sic) but one is assur and one is muttar on Pesach to drink. That's their argument in the video.

While this is a decidedly pro-murex video, there are a couple of minutes dedicated to one of the Englard Rabbis, in which he cites that a number of Gedolim (see also https://www.mywesternwall.net/2018/11/04/top-gedolim-that-wore-radzyner-techeiles.html) that wore or supported it.

My attempt to counter all the points on the "murex truth" video" linked above.

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    Can you summarize the contents of the links in your post here?
    – DonielF
    Commented May 31, 2019 at 21:05
  • I edited my comment. Hope this helps!
    – Rafi Hecht
    Commented Jun 2, 2019 at 13:54

If one is going to use the argument that we can't know for sure which tekheileth is the correct one, then it doesn't matter which one you use. You might not truly be fulfilling the commandment, but you aren't transgressing any as long as you don't use indigo to color your tekheleith. So if you don't feel certain that either are the real deal, and you know that you aren't committing a transgression, and you still want to wear one or the other, then what's a large consideration?

Price. i can order 3 or 4 sets of Radzyner tekheileth for every one set of Ptil Tekheileth.

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    I don't understand. Wouldn't you prefer to use one that seems more likely to be the real thing than the other? Wouldn't that increase your odds of fulfilling the mitzvah?
    – Jay
    Commented Aug 8, 2016 at 23:40
  • @Jay i agree that it would. But there are some who wouldn't care. And price has a large factor to do with it. From my understanding, there used to be funds to help people purchase techeileth and tefillin way back when, but now... not so much. i myself have many tallat katanim that are falling apart and are becoming pasul because my techeileith threads are snapping, and i can't afford to replace them =\
    – Aaron
    Commented Aug 8, 2016 at 23:47
  • Aaron, your last point goes againt Menachot, where techeilet is specifically referred to as expensive at the end of the description of the chilazon (daf 40-odd) Commented Aug 9, 2016 at 1:26
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    @NoachMiFrankfurt What counts as expensive today is very different from back then.
    – Double AA
    Commented Aug 9, 2016 at 2:06

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