Thermo Threads: Ziderman Techeiles Strings – A Blue Fringes Exclusive

Blue Fringes is proud to offer an exclusive line of Ziderman-style Techeiles. It’s presently available in Raavad and Tosafos thick.

Dr. Israel Irving Ziderman is an Israel-based biochemist, who – since 1969 – has pioneered the rebirth of Techeiles (Tekhelet), including: identification of Hexaplex (Murex) trunculus (banded dye-murex) as the hilazon; discovery of the unique MBI constituent of Techeiles dye; and of the thermochromic transition of natural MBI from violet to blue. He has found that the way to make the Techeiles is not to convert the murex dye to indigo photochemically by irradiation, but merely to expose it momentarily to ca. 80C, when it turns permanently from violet to a blue with no change at all in the molecular structure!

The result, for the batch currently available, is a much darker blue with a minor hint of violet. Some may see it and some might not. Part of it has to do with the lighting, part due to one’s color perception. That’s why the molecular structure aspect is more scientifically accurate.

This is an extremely limited batch of string sets and the price therefore is higher than a regular set of Techeiles. The dye comes from the trunculus, supervised Yirei Shamayim perform the manufacture, and in the initial stages Lishma is said.

How the Strings Look

Common Questions from Various Tekhelet Enthusuasts, with Responses from Dr. Ziderman

Note: Not all views presented below by Dr. Ziderman are shared by Blue Fringes.

  • Many of us are familiar with R’ Meir’s color designation of Techeiles being similar to the sea, which is similar to the sky, which is similar to the Kiseh HaKavod. That’s only one version of eight different variations. Other versions have Techeiles being compared to grass, trees, the sun, moon, and rainbow. At that point, it’s no longer about it being blue, it would be referring to concepts that move from the finite to the infinite. Still, blue of any shade will remind one of the sky. See R’ Herzog’s analysis on this Braisa here (page 88, printed Ph.D. thesis).

    However, Dr. Ziderman emphasises the Shema text`s adjacent imperatives “remember + do” and its immediate reiteration, namely:

    וראיתם אותו וזכרתם את כל מצוות ה’ ועשיתם אותם …למען תזכרו ועשיתם את כל מצותי

    On directly seeing the tekhelet-tassel itself, one should focus one’s attention straight to “remembering all the mitzvot“. This is achieved by remembering the Torah’s previously described other tekhelet, (Num. 4:6),בגד כליל תכלת which the Israelites saw, during their 38 years` wandering in the Wilderness, as it adorned the holy Ark of the Covenant that contained those very mitzvot! Compare to the version (h) in R’ Herzog’s above analysis, namely:

     ר’ נתן אומר: חביב מעשה הארון כנגד כיסא הכבוד של מעלה … ואף בשעה שהיו נוסעין, לא היו פורסים עליו לא בגד ארגמן ולא תולעת שני אלא בגד כליל תכלת ללמדך שהארון היה דומה לו לכך הבגד תכלת מלמעלה פניו נגד הרקיע הדומה לו וכו’ (במדבר רבא)

  • Ancient tekhelet was named “hyacinth purple,” and was similar shades to “kala ilan:” but, of course, “kala ilan” could be, and sometimes was, double-dyed with indigo and red to get violet kala-ilan. The word “purple” originally meant merely “dyed with shellfish,” without reference to its colour being blue, violet or purple. “Hyacinth” points us in the direction of the colour of that flower. The Gemara states that “Ani Hashem Elokeichem” means that only Hashem can tell the difference in its source (whether from Hilazon or kala ilan) since both give similar shades.

  • Plant indigo dye in Antiquity was a popular and lucrative imitation or forgery of Tekhelet, both having similar shades. From the times of the Geonim onwards, no Tekhelet was available to the Rishonim. So, from then onwards, none of them would have seen Tekhelet, and thus cannot be a source for describing its colour.

  • The fact is that a fresh dye, as obtained from an individual snail, will be either blue or violet.

    Consequently, the mixture from many snails, as used in manufacturing, is a violet.

    However, when momentarily exposed to gentle heating (60 degrees C), these violets immediately become the typical permanent blue-coloured tekhelet dye WITHOUT ANY CHANGE IN THEIR MOLECULAR STRUCTURE OR COMPOSITION, i.e. THEY ARE THE SAME SUBSTANCE AS HAD BEEN OBTAINED DIRECTLY FROM THE HILZONOT!

  • There is no comparison between the actions of “heat” and “light”.

    Light, as such, can have no effect on tekhelet itself. Because, in order for light to have any effect on the tekhelet compounds MBI and DBI, they must first be altered by synthetic chemicals to form their leuco compounds and thereby dissolved. Light irradiation on these leuco compounds’ solution, in an organic chemical reaction, severs the bromine irreversibly from the leuco forms producing leuco-indigotin. Then this leuco-indigotin is oxidised to indigotin that is the same as kala ilan. This debromination reaction was only discovered in scientific research in the 20th century, and thus was not available in antiquity. Otherwise, a blue is not formed, since, without the chemicals, no colour change can occur.

    Such a breakdown of the natural bromo-indigotins to form the mixture of indigotin and bromide is comparable to taking table salt, that is sodium chloride, and separating it to a mixture of sodium metal and chlorine gas.

    Another analogy would be spontaneous irreversible fermentation of dough to form chamets, which – of course – is then pasul for matsa.

    In contrast, momentary heating of the solid natural violet tekhelet to 60 degrees immediately gives a blue hue, due to a photochromic transition: no change has occurred in the chemical composition nor in the molecular structures. All the DBI and MBI are retained. No chemicals are used.

    It is important to consider that the indigo formed by “light” was developed by Elsner in a first premature attempt to get a blue from the natural violet, well before I discovered the “heated” blue.

  • It is fallacious to look for consistency in hue with untreated tekhelet. This is because naturally, it is a mixture of varying proportions of MBI, DBI and IND. The effect of mild heating on the hue could accordingly give mutable hues.

    However, that does not mean to say it should necessarily be of variable hue. We should just recognise that what you see is what you get. The hue/colour itself is not an independent diagnostic test of validity: rather we rely on the colour of the material that is nearest to the naturally obtained dye. The term “tekhelet” is not a specific tint/colour, but it is a material/commodity, just as are the gold and silver etc. in the list in verses Exod. 25:3-4!

  • Largely speculation! Let’s restrict ourselves to what can be confirmed empirically, and leave hypotheses to the investigators.

  • No! Tekhelet should be that characteristic colour-range given directly by the hilazon. The strength of the dyeing depends on dyestuff concentration and time.

    Regarding (2), I have never seen tekhelet by itself turning red.

    Also, it would depend on what hue you wish to imitate. Reds were added to imitate argaman!

  • Q.

    הייתי מעוניין לדעת, אם מישהו מעוניין להפיק תכלת מהחילזון, להפוך גוונו לכחול בשיטת  תרמוכרומיזם במצב מוצק, קודם צביעתו בצמר, רק היישר מן החלזונות, כיצד הייתם מציעים לעשות אותה?

    היום ישנם אנשים שצובעים תחילה הצמר בדיו החילזון לגוון סגול, אח”כ בחימום של הצמר הצבוע, הופך כחול.

    שאֵלתי היא לאלו המעוניינים להשיג גוון הכחול מן החילזון לפני הצביעה, ובמצב מוצק, כיצד דרך ראויה?


    זה בלתי אפשרי כי בשלב הצביעה יקבלו שוב צבע ויולט!


    I would like to know, if someone is interested in producing tekhelet from a chilazon, and wants to turn its color to blue through thermochromism in a solid state, before dyeing it on wool, only straight from the snails, how would you suggest doing it?

    Today, there are people who first dye the wool with the snail’s ink to a purple shade, and then by heating the dyed wool, it turns blue.

    My question is for those who want to achieve the blue shade from the snail before dyeing, and in a solid state, what would be the proper way?


    It is impossible because in the dyeing stage they will again receive a violet color!

Dr. Ziderman's Explanation

The Process

The Techeiles strings as a gorgeous violet, before boiling/heating.

The transformation to blue, after boiling/heating at 100 C for 10 minutes.


    Let's meet

    Let’s schedule a time to meet for strings and quality service.