Ask Ptil Tekhelet

Q. I have read extensively the writings of ancient historians regarding dying with Murex. They describe in fantastic detail the Royal Tyrian Purple that it produced. The fact that it also produced an indigo dye is mentioned virtually nowhere. (An ambiguous and subtle indication of this in Vitruvius is about all you'll find.) Why is this so?

A. R. Tavger explains that in ancient times “purple” referred to all the colors (blues and purples) that come from the snail, and it is only in more modern times when people made a point of differentiating in their speech when talking about the product in general. – Mois Navon

Q. Where do you buy the wool? Where is the chilazon from?

A. For our regular tzitziot we use a company called Vitalgo in Italy; for our niputz lishma tzitiziot we use a company called Summit in Israel. The hillazon lives in the entire Mediterranean sea; it turns out the State of Israel does not allow crustaceans to be fished off its coast and so we get our snails from fishermen in Croatia. – Mois Navon

Q. The Yerushalmi (p. 8a, ch.1 halacha 3) says that the hillazon has bones. The Murex doesn't have bones, so how do you explain this?

A. The Yerushalmi says that anything without “gidim ve’atzamot” (sinews and bones) cannot live more than 6 months. Now since we know that the Murex trunculus lives for over 7 years this must mean that it has “gidim ve’atzamot” – so presumably the shell which is like it’s skeleton was considered by the Yerushalmi to be its “bones” (see See Rabbi Menachem Burshtein’s “Hatekhelet”, p. 35, and especially R Herzog’s explanation of the issue on p389 of the same book). – Mois Navon

Q. I recently was discussing murex specimens with my friend, Zvi Herzig, and he mentioned the existence of blue murex shells. I know that pink shells are common; how common are blue or green shells? Is the murex always covered with growth that resembles the sand of the sea bed? From what I remember of the snorkling tour I took thirteen years ago, the shells I saw were a green-yellow that resembled the sand beneath them.

A. The shells, when dried and cleaned are neither pink, blue or green – they are “sandy” colored, with brown stripes. When they are in the sea, whatever grows along the sea floor, grows on them. The snails in Dor are covered in algae which ranges in colors like beige, green and purple. – Mois Navon

Q. Why do we assume techelet came from this snail opposed to the other dye producing snails?

A. There are only 3 dye producing snails in the Mediterranean: Murex trunculus, Murex brandaris (almost identical to trunculus), and Thaïs haemastoma (a distant relative). Technically specking one can produce blues and purples from any of them and it seems that they are all “kosher” for tekhelet production. One piece of evidence which points in the direction of different snails being used for different dyes is the archeological find at Sidon where a football field size mound of trunculus shells was found and off at a distance another football field size mound of brandaris and haemastoma was found. This led archeologist Alexander Dedikind (and Rav Herzog who writes about the find) to infer that separation was being done for different color production. There is a theory that the trunculus contains naturally more indigo than dibromoindigo as opposed to the other two snails which have more dibromoindigo than indigo and as such the trunculus tends to blue more naturally. But this is conjecture and, again, technically, one can produce blue from any one by simply exposing the dye to sunlight. – Mois Navon

Q. I've gotten mixed answers to how long after the death of the murex it takes for the dye to start to lose its effectiveness.

A. It starts within minutes. We did a test where we killed snails and used the dye at 15 minute intervals. All along the way one sees a degradation in dye making capacity, and after an hour it is impossible to produce dye. – Mois Navon

Q. Your research and work is absolutely fascinating! It's nice to see this ancient craft come back to life. I'm not convinced though that the murex is the creature that best fits the descriptions. Have you considered checking the heteropod family (carinaria, pterosoma, etc)? They are sea snails with only part of their body covered with a shell. The color of their bodies is like the sea in that they are mostly clear (transparent). Like nearly all gastropods they have blue blood. Of course that doesn't point to any particular heteropod! They are quite often pisciform (shape of a fish) with their fin and the way they swim. Just a thought! Keep up the good work!

A. Blue blood – does not necessarily make for a blue dye. There are many animals that have blue blood – as you mentioned – from lobsters to Octopus. Tekhelet has the unique property of dyeing fast onto wool – and that is a very rare property. Actually in the Murex snails, the dye (dibromoindigo) comes from the digestive system and is a result of two strange properties of the Muricae. First that they are meat eaters, thereby producing indole as a byproduct. Secondly, they choose to neutralize the poisonous indole using bromine instead of chlorine which would be the natural choice, since it is 60 times more abundant in sea water. Remember that the Tekhelet/argamman dyeing industry was the most important economic industry in the ancient Mediterranean. That means that we should know about it from historical records. Assuming that the Jewish tekhelet was the same as the blue dyed by the rest of the world, then the historical records we can search are much broader than just the Talmud and Midrash. I think that I can justify that assumption for a number of reasons. One obvious thing that points to the fact that tekhelet was identical for the Jews and the rest of the world is that the word itself actually predates the Bible. Also, Mordechai in Persia wears tekhelet robes when he is appointed to the premiership. So, what do the other sources say? Pliny, Aristotle and Vitruvius all write about the snails used in dyeing and those descriptions clearly point at the Murex. Archeological evidence is absolutely clear that Murex were used in a very extensive dye industry for thousands of years from Israel and Lebanon to Crete, Greece and Italy. I don’t know if this proves that there couldn’t have been another snail used, but if there was, then I would look for some record of its use. – Baruch Sterman

Q. In support of the Rambam's method of dyeing one half of a string, I would like to point out that the Moznaim (Hebrew - English) edition of the Rambam’s Mishneh Torah (Hilchot Tzitzit, Vol. 7, p. 199) has a footnote that states that there have been archeological finds of Tzizit from Bar Cochbah's Soldier's - that had half of one string dyed, as the Rambam holds.

A. The so called tekhelet that was found by archeologist Yigal Yadin is very questionable. I was privileged to see the find with my own eyes, and three points must be made clear:

1. The find consists of a purplish piece of wool wrapped with a string of linen. Yadin explained that the combination of wool and linen was only allowed for tzitzit and therefore this must be tzitzit. This is a specious conclusion.

2. The dye used on the wool was tested was found not to be of snail origin. Yadin explained that since it was important for the Jewish rebels to have tekhelet and yet they had no access to the sea it must be that they used a counterfeit to get this purple (Yadin assumed tekhelet was purple, probably because he relied on a poor translation of the Bible). In any case this conclusion is also specious since it was well known that counterfeit tekhelet was absolutely forbidden by Jewish Law.

3. The find did not include any “strings” that might have been used for tzitzit other than the linen sting wrapped around the wool tuft – and the dye was not well absorbed by this string.

Our explanation of Yigal Yadin’s find is that the people at Masada were simply dyeing tufts of wool for non-tzitzit purposes. In order to dip the wool in to the dye-bath, they wrapped it with a piece of linen which absorbs little to no
dye and thus doesn’t waste any of the precious dye.

– Joel Guberman

Q. Your website has been a brilliant resource for me. I have some questions if you could please advise me. 1. We have no definitive, exhaustive list of the attributes of tekhelet. Even if we have found a dye which fits the descriptions of chazal (of which some are quite ambiguous) that we do have, how can we be sure it is tekhelet without a mesoret or a ruling by the Mashiach himself? 2. Since at best we are in doubt as to whether we have the correct dye, the Tosefta Menachot 9:6 indicates that if it is the wrong color we have made the tzitzit pasul and we are therefore mevatel mitzvath aseh by wearing the begged. Is this not correct? 3. Finally some poskim (e.g. Rav Ben Tzion Abba Shaul) have expressed that wearing tekhelet would be motzi la'az al harishonim (since our parents have not worn tekhelet etc.). Why would you feel that this is not the case?

A. 1. We are only as sure as the evidence presents. That being said, there is quite a bit of evidence – see my table:
Regarding Mesorah, see my article:
Regarding the Mashiach – there is no mitzvah in the Torah which is dependant on
the coming of the Mashiach.

2. Regarding wearing false tekhelet, see my article:

3. I do not understand this reasoning because we are not proposing to do
something against which the Rishonim didn’t do. Tekhelet from the Murex
trunculus was unknown to the Rishonim – again, see my article:

– Mois Navon.

Q. What is the difference between the Radzin techelet and the Efrat techelet (from the Murex snail)? Of course, the price is one. Nevertheless, I could not find something on your site to help me decide which to use. Some years ago, I had tied the Radzin techelet to my tallit gadol and, as time has passed, I'm now looking to replace my tallit and so am revisiting the subject. Your assistance is much appreciated.

A. Radzyn tekhelet is made using the ink from a cuttlefish (Sepia officinalis). R. Herzog, who corresponded with the Radzyner Rebbi about tekhelet, obtained the Rebbi’s formula directly from the Rebbi. He gave it to chemists for analysis and they told him that it was simply the formula for the well known synthetic dye “Prussian Blue”. They explained that the blue coloration comes from added metal filings, the cuttlefish ink being completely burned off and only supplying Nitrogen which could be obtained from a multitude of other organic sources such as Ox blood. As such, the Rebbi had apparently been duped by the chemists of his day because he writes explicitly that the color of the dye comes from the hillazon itself:

“And with the help God it has come to my hands to extract, from the blood of
the cuttlefish which is] black as ink, the color tekhelet in a manner which
nothing affects the color other than the blood of the hillazon; and the
chemical additives are colorless and only work to extract the color from the
blood” (Sifrei HaTekhelet, Ptil Tekhelet, p.168).

Another important point is the color itself. The Gemara (Baba Metzia 61)
teaches that tekhelet is identical in color to the forgery dye “kela ilan” –
known as “indigo” (used in the past for many things, such as Levis jeans). The
Radzyn dye is not even close to resembling this blue, whereas the dye from the
Murex trunculus (what you refer to as “Efrat techelet”) has been found not only
to resemble it visually, but is molecularly identical to indigo!

It should be noted that none of this is to impugn the good name of the Rebbi;
on the contrary, he was undoubtedly the father of the tekhelet renaissance. He
did much important work and investigation on a great many aspects of this issue
which we still refer to today. And more importantly, he awakened in Am Yisrael
the possibility of renewing this lost mitzvah d’oraita – not to speak of the
awareness to work for the rebuilding of the Beit Hamikdash – she’yehiyeh
bimheira b’yameinu.

– Mois Navon.

Q. Is there any relationship between tekhelet and shalom and achdut with klal yisroel?

A. The Radzyner Rebbi concludes his book “Ptil Tekhelet” with the following idea:

And now God should bless Israel, in the merit of the mitzvah of tzitzit as it says, And He will remove from [Israel] all evil and all sickness and all wounds and all curses and all baseless hatred (sinat hinam), and as the RM”A from Pano explained (in Maamar Tzvaot Part 2): And know that Tekhelet has the gematria “Sinat Hinam”, and therefore it is possible to say that the reason why Korah dissented about tekhelet, because he had sinat hinam for Moshe and Aharon, and thus he mocked (mitlotzetz) the benefit (maalat) of tekhelet which ATONES (mechaperet) for sinat hinam, as I mentioned before why it atones for sinat hinam, but that is only when the person does teshuva gemurah and removes it from his heart. And it will benefit him greatly to reach this desire [apparently the tekhelet will help to facilitate the person to do teshuva over sinat hinam – M. Navon] – so ends the RM”A of Pano. And indeed this is the main thing which delays the redemption, as it says in Yoma (9b): but the second mikdash where the people were involved in Torah and Mitzvot and Gemilut Hasadim, so hy was it destroyed? Because of sinat hinam, which teaches you that sinat hinam weighs equivalent to the three sins of idol worship, illicit relations, and murder. And may God gather in our dispersed from the four corners of the earth, and redeem us soon and unify our hearts to love and fear His name to unify Him with love, and bless his people Israel with good life and peace.

– The Yeshot Malko wrote that the renewal of tekhelet is a sign of the geulah, and the geulah is of course to bring shalom.
– Shoheir Tov on Tehilim 90 writes “If Israel wears tzitzit and tekhelet they would not be “achurin” (besmirched) because when they look at their tzitzit it is as if the shechina is present amongst them (shruya beineihem), and it is as if they are busy doing all the mitzvot.” And of course the shechina is not shruya unless there is achdut.

– Mois Navon.

Q. Is possible to wash cotton tzitzit with techelet in the washer? In hot water? Does tekhelet run?

A. One of the fundamental characteristics of tekhelet is that it not run – in the words of the Gemara “lo ipareid hazutei”. As such you can wash tekhelet without fear of it running. You can even use bleach! Of course you can expect the garment and all the strings to wear with time and washing as all materials do. The only thing about tekhelet is that
RELATIVE to other natural dyes it is one of the fastest known dyes.

But be careful not to use any special cleaning agent which contains a reducing agent; this will definitely cause the dye to wash out, because “reduction” is the chemical process which is used to allow the dye to go into the wool – as such the process also works in reverse.

By the way, though I imagine when you said “cotton tzitzit” you meant the garment is cotton and the strings are wool. In any case it is worth mentioning that though you may have cotton tzitzit strings, the tekhelet strings must, halachically, be dyed in wool.

-Mois Navon.

Q. Regarding the absorption spectrum measuring 613nm, I was wondering, can it be said that of the two characterizations, emission and absorption, one is more accurate or more popularly used, or is one simply the direct inverse of the other? Nobody ever uses the emission spectrum unless you specifically state it. That's just practical, since there are very few light sources, but everything in the universe absorbs. If you were talking about lasers, or radiation, then you would have a reason to talk about emission. For virtually any other thing, you would be talking about the absorption spectrum.

A. By the way, they are not at all inverse of each other. In fact, they are usually very
similar. If you can get something to emit radiation, then it will usually emit at the
same wavelengths that it absorbs. The reason for this is because both emission and
absorption happen when an atom or molecule jumps between energy states. In the
case of emission, the atom falls from a higher state to a lower one and the energy
difference is emitted as a photon where the energy = h* the wavelength (h is Planck’s
constant). For absorption, a photon with the energy equivalent to the gap between
energy states in the atom will be absorbed and the atom moves from the lower state to
the higher state. The quantum mechanics of the atom determines it’s energy states,
but the gaps between them are the same in both directions (moving up to higher states
or down to lower states).

As for our eyes, there is obviously a big difference between the case where we see on
pure wavelength (like in the case of a laser where you see the pure red color because
that is the only wavelength emitted by the laser, and so when it reflects off anything it
will stay that red color), and the case of white light bouncing off an object after
having some wavelengths absorbed.

Here’s a good experiment. Take a shiny patch of blue (like a tablecloth that is shiny
and bounce a laser pointer off of it. It should still look red. See if you can bounce the
laser off the shiny blue patch onto another object (say that is yellow), the light should
still look red. Try the same thing with a flashlight. If you shine the flashlight directly
onto the yellow thing it will look yellow. If you shine it onto the blue and then the
blue light illuminates the yellow object, it will look different.

– Baruch Sterman

Q. When bathing in a beach near Haifa, my 10 year old son found a beautiful small snail, light blue colored, about 1.5 cm in diameter. He took it out of the water to show it to me. While walking out from the water, the snail secreted some air like bubbles along with a lot of purple dye which tinted his fingers in a bluefish-purple color. He tried later to wash it up with a very strong (dish) soap and the color finally faded a little but the tips of his fingers stayed tinted until next day. Unlike the Murex snail, this snail was much smaller, glossy and smooth and light blue colored. Furthermore, the dye came out as a secretion of the live snail and there was of course no need to kill it or break it in order to obtain the dye. I would appreciate it very much if you could inform me if you checked out other snails along with the murex snail and why were these other snails disregarded.

A.Congratulations! Your son found the Janthina snail which Rav Herzog suggested as a possible candidate for the source of tekhelet after he researched the murex and found that it only gave a purplish color. (Prof. Elsner’s discovery of the Murex dye turning blue in the sun was only in the 1980′s!) Prof. Elsner and others have researched this Janthina snail and determined that the color in the snail is not a steadfast one. We have collected them in the past and brought them both to Prof. Elsner and Prof. Zvi Koren who both concluded that the color in the snail is not stable. There is someone by the name of Shaul Kaplan who has been convinced that the Janthina is in fact the tekhelet source. He has published some of his stuff and has a web site. Unfortunately, he will not let any significant scientists study the dyed string or be told the process he uses for dyeing. Rav Eliyahu Tavger was asked to respond to his articles and has a small piece on our web site in response to why the Janthina is not the most likely source for tekhelet even if it would be a good dye. Rav Tavger also found that several of Shaul Kaplan’s sources were not quoted correctly, and are in fact misleading.

We are still interested in doing more research on everything connected to tekhelet, and if you should again find the Janthina alive, please put it in a jar with sea water and call us. We would love to have them in our aquarium to show people what they look like as well as provide the dye for further research for those who are interested.

– Joel Guberman

Q. I read your source book, which showed a diagram of the molecular makeup of Tekhelet, and showed that the wavelength of Tekhelet is exactly 613 nanometers at its peak. This would be very interesting except for one thing. As the enclosed chart shows, from a psychology textbook, the color yellow is 613 nanometers, not Blue. Blue is 450 nanometers

A. Thanks for the question. The spectrum that is used in spectroscopy is the *absorption* spectrum. You are referring to the *emission* spectrum. If you have a source of light, it emits radiation at various wavelengths, and each wavelength corresponds to a color that our eye detects. There are virtually no natural sources of light that emit pure colors (a laser does that, but there are no natural lasers). The sun, for example, emits a very wide spectrum of light. When that light hits an object, the object selectively absorbs some of the wavelengths, and reflects others. The reflected light then hits our eyes, and we see the full spectrum of light (that the sun emitted) minus the absorbed light which stays in the object. It is that complex *negative* that causes our eyes to perceive the color. So in the case of tekhelet, our eyes see white light minus the yellow of the absorbed 613 nanometers (again that is only the peak, the actual curve of absorption is not sharp, but has a spread and a contour). Our brain perceives that as blue.

-Baruch Sterman

Q. Are there any concerns with the process of making Tekhelet and the issue of tzar baalei hayim?

A. The issue of “tzar baalei hayim” is undoubtedly an important one which keep us sensitive
to all of God’s creations. Included in that, for example, is we must feed our animals
before we feed ourselves. That being said, it must be clear that this does not mean we
hold the same banner as animal rights groups who are against any and every use of
animals. In fact just the opposite, God commanded (Gen. 1:28) Man to rule over the
animal kingdom and make use of it for the betterment of mankind. There are countless
examples – from the mitzvot of offering korbanot, and the statement in the Gemara that
true rejoicing is with meat and wine; and of course the three dyes of the Mikdash
(tekhelet, argaman, tolaat shani) are all from the animal kingdom. The only proviso to the
overreaching divine command of “Subdue [the earth] and have dominion over the fish of
the sea, and over the fowl of the air, and over every living thing that creepeth upon the
earth” is that we not abuse the animal kingdom.

“Tzar baalei hayim” is a warning (a) not to harm animals for no reason, (b) not to inflict
undue pain when we are utilizing them for legitimate reasons. However, the notion of
“undue pain” must not be taken out of context. That is to say, when we need to slaughter
a cow, we are not bidden to anesthetize it, but simply to perform the act in a way which
will not cause more suffering than is normally attendant with such a procedure. At the
end of the day, slaughter is slaughter and there is going to be some pain involved.
(Indeed, it should be noted that though we try to minimize suffering to the animal that
is being killed, the actual killing of an animal is not considered “tzar baalei hayim” –
(see Shu”t Har Tzvi, Orech Hayim I:194).

So in answer to your question regarding the dye extraction from the hillazon (Murex
trunculus), we perform the procedure in its normal way without causing undue pain over and above what is naturally attendant in killing a living creature. The snails are kept in water for as long as possible before removing the glands. After the gland is removed the snails have been used for bait or given to non-Jewish people to eat in the area.

– Mois Navon.

Q. I bought your dye sample kit and used in a lecture at my school. When I showed the students the dyed pieces of wool (blue/purple), one of the boys asked, Why is it that the raw piece of wool looks a lot lighter in color than real finished tzitzit?

A. There are a few of factors which influence the final shade: (1) ratio of dye:water (2) ratio
dye:wool (3) time allowed for dye to set in wool. (1) If you have a very diluted solution,
the final outcome will be lighter than if you have a concentrated solution; (2) If you put
in a lot of wool relative to the amount of solution this will also play into having a lighter
outcome; (3) Even if you have high dye concentration and a little bit of wool relative to
the amount of solution, if you don’t let the wool sit in the dye solution for long enough, it
will come out lighter than if you let it sit.

– Mois Navon

Q. In terms of the styles of tallitot that you sell, what is the standard style? What is the Beit Yosef style? And what is the Super Prima style?

A. In terms of quality they are both the same high quality wool. The Beit Yosef is White
with White Stripes, the Super Prima is White with Black Stripes.

– Mois Navon.

Q. I am doing research about Lydia - seller of purple goods - in the Acts of the Apostles, chapter 16. I am wondering where she would have obtained her purple dye. Some commentaries say she did not obtain it from snails but from a root or plant. She lived in land-locked Philippi (although she was from Thyratira) and the nearest coastal city was Neapolis--would it have been possible at all for her to acquire the snails there or were they exclusively found along the coast of Israel and Lebanon? Also, if the emperors were restricting use of purple in 55 CE--when Paul went to Philippi--it must have been a different shade of purple she was dyeing/selling, correct? Any light you could shed on this would be very helpful!

A. The most ubiquitous source to the best of my knowledge was the Murex family of snails,
which was (and is) available throughout the entire Mediterranean Sea. Transport of the
precious dye source reached far and wide (the Talmud provides evidence that it reached
ancient Babylonia – i.e., Iraq/Iran). There were purple dyes which used alkanet (from
Anchusa tinctoria) or orchil (from Rosella tinctoria) or alternatively to get better fastness
they used combinations of madder or kermes (for red) in combination with indigo (for
blue) to achieve purple (“The Red Dyes”, Sanberg, p.38, 40).

In “The Royal Purple and the Biblical Blue”, Rabbi Herzog, p.22-23 gives a list of
various finds:
– William Cole found the Purpura lapilus off the British Coast to produce purple.
– Pere Plumer found Purpura lapillus off the Antillian Islands of the Grenadines
– There is some evidence that purple was used in Cerntal America especially near Santa
– Rav Herzog also discusses Iakinthos, Hyacinth and other possible dye sources.

See also Aristotle’s History of Animals Book V, ch.15.

– Mois Navon.

Q. Who is the mashgiach on the process making sure it's lishma, etc.? Who gives the official hechsher?

A. R. Eliyahu Tavger is the Rav of the Amuta. The workers doing the dyeing, spinning,
twining of the threads are all yirei shamayim Jews who are very careful to state explicitly
before every process, “L’shem mitzvat tzitzit.”

– Mois Navon.

Q. Rambam in Peirush HaMishnah writes that we can't make tekhelet because of color uncertainties, contradictory to what he writes in Hil. Tzitzit. Using modern science we are able to compare it to indigo. My question: is there only one color that can be produced from the indigo plant, or is it possible to adjust it to darker/lighter hue by adding or subtracting amounts of indigo?

A. First of all, I believe it is fair to say that in a case of contradiction that you mention, we
use the Rambam’s Mishnah Torah (Hilchot Tzitzit) for halachic decisions.

To the best of my knowledge the indigo plants produce only one color – indigo. However
this does not mean that we can’t produce different SHADES, it is just a matter of
dilution. What is important here is that the exact HUE be correct. Technically speaking,
the hue is measured by the absorption spectrum of a particular object, regardless of shade.
The indigo dye produced from the plants is precisely the same hue (has the exact same
absorption spectrum) as the dye produced from the Murex snail. (By the way, this is one
of the strongest points in favor of the Murex trunculus, since according to the Gemara in
Baba Metzia 61 – only God can tell the difference between strings dyed with the plant
(Kela Ilan) and strings dyed with the hillazon.)

– Mois Navon.

Q. Is your final color different then that of the Radziner's?

A. Yes, the final colors are very different.

– Mois Navon.

Q. There seems to be a machloket between Rashi and Rambam concerning the final color of tekhelet. Rashi (in the name of R. Moshe Hadarshan): midnight (dark) blue; Rambam: midday (light) blue. Is it possible to dye with the Murex to obtain both these shades, or only one?

A. You are correct that there is a machloket as to whether the color should be dark or light.
Rav Yehuda Rock writes about this in his article in Techumin and his latest book called
“Eved HaMelech” – you can see the relevant section in his article on our website
( see the bottom of p.17 “Behirut Hatekhelet”. To cut to
the chase – he states that the issue is “not maakev” – that is, one still fulfills the mitzvah
whether it is light or dark.

And yes it is possible to achieve all the shades from very light to very dark using the
Murex trunculus – it is simply a matter of more or less dilution of the dye solution.

– Mois Navon.

Q. Could you explain to why, in Talmudic times, did they have to do teima? Is it still necessary?

A. “teima” refers to the procedure of taking a sample of the dye solution on to a test piece of
wool to determine if the dye in the vat has reached the proper state to start dyeing wool.
The need for such a procedure seems to indicate that vat dyeing was the method
employed since in vat dyeing you don’t know what color you will get until the dye
solution is oxidized in the fabric (i.e., in the vat it is in a “colorless” [really its yellowish]
chemically reduced state). In ancient times this was probably very important since the
process was less controlled, they threw in many snails and fermented them for a week; it
wasn’t known exactly when the solution had reached the proper point for dyeing.

Today, after much fine tuning, we weigh out fairly exact quantities of snail glands and
add precise measures of specific chemicals – all of which combine to make the dye
solution within a matter of minutes. We have reached a relatively stable process for
which we are not in need of performing samples to insure the proper color outcome. (As
far as I am aware, teima was performed out of a technical necessity not a halachic one).

– Mois Navon.

Q. Can you explain the stages of the dye process, particularly, when the color takes effect?

A. In order to get a first hand understanding of the dye procedure, I recommend getting one
of our dye kits from our store. Basically, when the liquid comes out of the snail its a murky clear substance; in light and oxygen it slowly turn yellow, green, blue and finally settles at almost blackish purple. This is what we call the “dyestuff”. We then take the dyestuff and put it in boiling water with a base which helps to dissolve the meat in the dyestuff – the solution at this point is blackish purple. Then a reducing agent is added which causes the dyestuff to “reduce” and the
solution becomes a yellowish liquid. Following this an acid is introduced to neutralize the pH of the solution (the color doesn’t change). The wool is then soaked in the solution and when it is removed it has the yellow color of the reduced solution. Slowly as the solution oxidizes it turns either purple (if the reduced solution was kept in the
shade) or blue (if the reduced solution was exposed to UV).

– Mois Navon.

Have a question that we didn’t answer above? Send us an email and ask Ptil Tekhelet your question!