[Avodah] tekhelet is midnight blue

[Micha Berger]

On Mon, Feb 28, 2011 at 10:10:16PM +0200, R Eli Turkel wrote to Areivim:
: https://www.nytimes.com/2011/02/28/world/middleeast/28blue.html

Sorta...

We know with more certainty than we know what tekheiles is that argaman
is a murex-based dye as is Tyrian Purple (hainu hakh, but different uses
implied). Which means that if you find a sample of dye, how do you know
the intended use was tekheiles? In fact, this patch has a purplish hue,
not matching the indigo color of kaleh ilan (the indigo plant, a member
of the tea family).

Murex dye is naturally purple. It turns blue by exposure to sunlight. I
would think that one could make a basically blue dye but has a pronounced
purple tinge by fixing the dye before all the purple is broken down.

I can't find R' Dr Koren's source for assuming this sample is tekheiles
in particular.

The other thing is that the darkness of the color isn't a only a function
of which dye is used, but the saturation of the dye. Color can be broken
down into hue (where on the spectrum it is), saturation (the intensity
of the color) and value (dark vs light). Of the three, using a specific
dye only specifies hue, and causes some relationship between saturation
and value. E.g. if you use very very little dye on a white string,
you would get a pale blue -- even though you're using the same dye.

Tir'u baTov!
-Micha

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