Debate Responses
How can we be so sure that the dyeing process today is authentic for kosher Techeiles?
The procedure for dyeing תכלת from the murex snail is precisely as the Gemara describes: מנחות )מב ע”ב( “אמר ליה אביי לרב שמואל בר רב יהודה: הא תכילתא היכי צבעיתו לה? אמר ליה: מייתינן דם חלזון וסמנין 55 ורמינן להו ביורה ]ומרתחינן ליה[…”. “How is this תכלת dyed? Said he: We bring the blood of a חלזון and סמנין and place them in the vat and it is then boiled…”
The procedure for dyeing תכלת from the murex snail is precisely as the Gemara describes:
מנחות )מב ע”ב( “אמר ליה אביי לרב שמואל בר רב יהודה: הא תכילתא היכי צבעיתו לה? אמר ליה: מייתינן דם חלזון וסמנין 55 ורמינן להו ביורה ]ומרתחינן ליה[…”.
“How is this תכלת dyed? Said he: We bring the blood of a חלזון and סמנין and place them in the vat and it is then boiled…”
Today, the procedure is the same (See photos on page 105):
1. The secretion is mixed with water and is solubilized with a mixture of sodium hydroxide (caustic soda) or sodium carbonate. It is then reduced with sodium dithionite (also known as sodium hydrosulfite). These two ingredients adjust the pH of the solution and allow the dye to bond to the wool. These ingredients are used for standard vat dyes56 and have the identical effect as those used in ancient times (wood ash etc.)57. As the Rambam and Rashi state, the procedure follows that of standard dyers58.
2. The solution is then boiled, and the wool is placed into it for a few minutes, while continuously being heated. Upon removal from the solution, the wool becomes a brilliant blue.
Footnotes
55.
“S’mamin are coloring agents—types of dye stuff. As it says in Bavli (Bekhoros 141b), they asked: ‘Some apply s’mamin to wool…’”
56.
“See Milner 1992.”
57.
“
The ideal pH is about 7–8. You can get there using various natural materials—like wood ash, etc. Boesken & Kanold (2005) and others suggest these are the same s’mamin the Gemara mentions. See the comprehensive article ‘Dyeing Techeiles according to the Rambam and Using Natural Dye Agents’ by Prof. Zohar Amar and Dr. David Illouz (HaMa’ayan, Tammuz 5773, vol. 206).”
58.
“Rambam (Hilchos Tzitzis 2:2) explains:
‘How do they dye the techeiles for tzitzis? They take the wool, soak it in lye, then wash it until it’s clean, and boil it in the bath—just like dyers do so the color will absorb. Next they bring the chilazon’s blood and add it to the dyebath, together with s’mamin like k’minia and similar stuff—again, like professional dyers do—then boil in it until the wool turns that sky‑blue color. That, my friends, is the techeiles of tzitzis.’
And in Kesef Mishneh he comments:
‘“How do they dye techeiles…”—it seems our Master wrote this from his own knowledge, following the dyers’ methods.’
Rashi there (ad loc. on Tzitzis 2:2) adds:
‘“And s’mamin”—to dip in them, following the dyers’ usual practice, using a vat called a bayitza.’”
The dye process in Chazal doesn’t match Murex chemistry.
Gemara mentions sammanim (chemicals) and vat-dyeing. Murex dyeing is a vat process using reduction and oxidation to bind dye to wool. Ancient techniques align perfectly with Chazal’s description.
Source: “Sammanim,” pp. 40–46