The Tekhelet Institute acknowledges that murex trunculus indigo is molecularly equivalent to plant-based indigo that was available in the ancient world for far cheaper (kala ilan). They reason that the gemara's test that failed kela ilan was not due to an inherent weakness to the fastness of the dye. If that is the case, do they (or anyone else) present an argument as to why ancient aristocrats (including outside the Jewish world) would not have just had quality batches of plant-based dye made rather than rely on the pointlessly (for non-halachik purposes) expensive murex dye? Isn't this a rather damning argument against the species being the chilazon? Or was this the ancient world's equivalent of DeBeer's getting everyone to buy worthless chips of carbon when they get married?

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    I assume I am missing some background info, but how do you know that ancient aristocrats didn't have batches of plant-based dye? – Y     e     z Apr 14 '15 at 14:45
  • Let us continue this discussion in chat. – Loewian Apr 15 '15 at 2:53
  • @yEz I'm sure they did, i.e. kala ilan. But for some reason this didn't deter them from spending considerably more in order to get what according to the Tekhelet Insitute is chemically identical... – Loewian Apr 15 '15 at 23:48
  • @yEz (Notwithstanding, I still think they have a pretty solid argument - I'm just curious as to this point...) – Loewian Apr 15 '15 at 23:49
  • @DoubleAA "The blue dye used for textiles of Egyptian mummies may, in some cases, come from an Indigofera species but woad (Isatis tinctoria L.) is another indigo-blue producing plant known to ancient Egyptians." from: database.prota.org/PROTAhtml/Indigofera%20tinctoria_En.htm (Keeping in mind the tekhelet used in the mishkan were brought from Egypt) – Loewian Apr 16 '15 at 4:12

I don't know if they address this concern particularly in terms of the expense.

However, the knowledge that murex indigo is chemically identical to plant-based indigo is something knowable only in the 20th and 21st century, when we know about atoms, molecules, and chemicals. If plant-based indigo failed the gemara's test for fastness, and this was just a side-effect of the dyeing or production process, how can you assert that the ancient dyers knew this? It is at least as plausible that they did NOT believe that it was identical (other than having the same / similar color). They may well have believed that color-fastness or lack thereof was an intrinsic property of the snail / plant.

Furthermore, while plant indigo can be the equivalent of murex indigo, there are actually different shades and hues. I know the techelet on my tallit is a slightly different shade than the techelet on my father's tallit, and both of them are murex techelet. This varies based on species and even the location the species from which the techelet is gathered.

From some quick searching, here are people who make related points to what I wrote above. From The Chemical History of Color, page 66, about the variation in hue because it comes from an animal:

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and from The Rarest Blue: The Remarkable Story of an Ancient Color Lost to History, page 230, about yet-to-be-understood reactions that involve the methods by which the ancients dyed:

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  • +1 Those are definitely very relevant sources though I think if anything they raise even more potential questions regarding the new tekhelet (Full disclosure - I'm not arguing from some traditional/chareidi anti-novelty agenda. I myself do wear techeles on my tallis [at least misafek] and am planning on getting more soon for my tallis katan as well...) The first source implies that even if we knew murex was the right species, we might not have the right halachic min even within that species. The second implies the color might be entirely off and should really be more of a night black (?). – Loewian Apr 14 '15 at 16:07
  • At the end of the day, my understanding was that tekheles is assumed to have been a dye widely used by the aristocracy. If we assume the dye was just as fast, was kala ilan a later discovery that didn't catch on for socio-cultural reasons? (In light of the current diamond-industry-generated aversion to created diamonds [or before that to cubic zirconia], perhaps that's not entirely unreasonable though there's no saying this won't shift in a few years.) – Loewian Apr 14 '15 at 16:12
  • In fact that first source you cite about the differing numbers of pigments amongst the subspecies could be of particular concern since the tekhelet institute gets its murex snails from Croatia. (Time to push for a North Israel tekhelet black market;) – Loewian Apr 15 '15 at 3:15
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    I don't think that subspecies were necessarily intended here (such that it would be a different min). Rather, same species but the effect of the environment. Or if genetic, not necessarily would Chazal have considered these halachically a different min, such that it would not be deemed Chilazon and techelet. (However, the color variation might well have been a reason that aristocracy might not have gone for it, since they would not be able to target the precise hue.) but why think black? en.m.wikipedia.org/wiki/Midnight_blue – josh waxman Apr 15 '15 at 8:08
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    @josh_waxman I meant black market - as in: if the government won't allow religous Jews to harvest authentic north Israel chilazonim by legal means, perhaps someone needs to learn how to farm them secretly... (Who knows, maybe the chemical composition is somehow different enough to distinguish it significantly from kala ilan- wouldn't be the first time modern science didn't predict ancient knowledge: nbcnews.com/health/health-news/… – Loewian Apr 15 '15 at 23:55

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