What is the significance of the black stripes on the Talis? When did these stripes find there way on the Talis?

I’m sure you know that the mitzvah of Tzitzis in the Torah obligates one to tie four strings on the corner of a four-cornered garment. One of these strings is meant to be dyed with a blue color called “techeles”. At some point in our history, the exact identity of the “chilazon”, the creature from which the dye is extracted, became unknown. In order to serve as a reminder of the missing aspect of the mitzvah of Tzitzis, the custom began to place blue stripes on the Talis, which eventually evolved into black stripes.

Sincerely,
R’Daniel Fleksher