Are There Secular Records Describing Fake Tekhelet?

[Shlomo Scheinman]

When I say fake I mean a non-durable dye that colors wool blue.
And if such records exist, what proof was brought to prove that the Tekhelet was indeed fake?

It is a separate debate, could a durable dye that dyes wool blue, and is not from the chilazon be considered Tekhelet or not, which I do not wish to discuss at present.
 
 

[Mr. Genugshoin]

Are there secular records of real techeiles?

Kala ilan did not fade, it was durable

[Shlomo Scheinman]

It is not necessarily true that Kala Ilan is durable. I got wool samples dyed with the plant dyes thought to be Kala Ilan and although they didn't fade immediately , much of the samples did end up fading their blue color.
 

[MIlanH]

The גמרא in ב"ק צג, ב says that קלא אילן is a very durable dye

[Shlomo Scheinman]

This is the Sefaria.org translation of Baba Kama 93bAnd when it is taught there, in the mishna cited above, that if one did not manage to give the sheared wool to the priest before he dyed it he is exempt, and this ruling was established in accordance with all opinions, it was not stated with regard to ordinary dye but with regard to indigo, which cannot be removed with soap and therefore effects a permanent and therefore significant change.

The Gemara simply states Kala Ilan (understood by Sefaria.org) to be indigo cannot be removed by soap.
It does not say it is durable over a long period of time.
The Kala Ilan samples I received were often not durable. 
 

[MIlanH]

Well however you translate it, צפון was a substance that was able to remove all dyes, besides Kala Ilan. So you see from there, at least in comparison to other dyes, Kala Ilan is the most durable.
 

[rhecht]

See this on Sapoon, which more than likely was the Tzafun in ancient times: https://bluefringes.com/2022/07/24/the- ... poon-soap/ . Bottom line it wasn't the same type of soap we use today. It was much more caustic!

[Shlomo Scheinman]

Plant Indigo (Kala Ilan) dyes in modern time fade over time.
From my research it appears that was probably true for most if not all of the ancient dyeing process for indigo.
See for example:
https://denimhunters.com/denim-wiki/den ... nim-fades/

Indigo-dyed denim is not like other fabrics. With wear and wash, the deep blue colour slowly turns brighter and the white core of the yarn slowly appears. In other words, it fades.

 
 

[Shlomo Scheinman]

I must add that although the expert at the web site on the fading of plant indigo dyed jeans attributed all the fading to extended washing, I feel there is an additional factor at play.
The naturally dyed Kala Ilan samples that I obtained were never washed at all, yet still faded over a long period of time.
I am looking around the internet for a better answer.
 

[Shlomo Scheinman]

I found another web site that makes the claim that sunlight alone can cause indigo dyed fabrics to fade.
https://www.naturaldyekits.com/sun-fading-of-indigoQ: Will sun fade the indigo? I noticed my indigo was a lot darker when I first placed it on the line to dry.A:  Yes, sun will naturally fade indigo. However, it takes days, weeks and months of UV exposure to remove substantial amounts of color. It sounds like you're describing the process of lightening that naturally happens when the piece dries out. Wet indigo dyed textiles always appears darker than the same fabric when dry. I recommend two or three more dips in the indigo vat AFTER you see the fabric reach the shade that you want.Re: actual sun fading of indigo dyed textiles : In John Marshall’s book Singing The Blues (which I highly recommend as a practical guide to working with indigo), he published photos of fabrics that have been exposed to comparable amounts of sunlight. One piece of fabric had been treated with a soy-milk after bath, the other received no such treatment. The fabric which received a layer of soy milk following dyeing was appreciably better at resisting the UV fading effects of the sun. I’m now firmly in support of dipping all my own indigo dyed textiles in a solution of soy milk (I’ll make my own from whole soy beans if I have the time, but will also use pure, no-sugar-or-flavor-added bottled soymilk) after their pH balancing rinse and allowing the soy to dry on the fabric. I won’t wash the item for a month to allow the soy to properly cure onto the fabric.