Blue Fringes Discussion Forum

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As Baruch Sterman pointed out in a lecture on Tekhelet, the molecular difference between Tekhelet dye and plant indigo is that Tekhelet dye contains Bromine.
My hypothesis is just like soy milk helps plant indigo better resist UV ...

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-indigo Q: 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 ...

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 ...

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/denim-explained/why-denim-fades/
Indigo-dyed denim is not like other ...

This is the Sefaria.org translation of Baba Kama 93b And 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 ...

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.
 

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 ...

In my article in Techumin which is translated into English at https://vilnagaon.org/argaman/
I deal at length with the color of argaman and bring down the psak of Rabbi Yechiel Michel Epstein, author of Aruch-Hashulchan (in Aruch Hashulchan Ha’atid, Klei Hamikdash, Siman 28)