Ptil Tekhelet is a shade of the blue color, which is mentioned in the Torah. It considers being precoius commodity like silk, silver and gold.
There is a biblical precept to tie a thread of Techelet around the tzitzite of curled clothing. In addition, Tekhelet is required in the clothes of the clergymen. Moreover, it is also required for covering the holy vessels. Gradually, it spreads in the ritual part of the clothing of religious Jewish people. Tekhelet is not used for dyeing regular clothing like all natural dyes of animal origin.
Ptil Tekhelet was first mentioned in history in 1991. It is the main provider of Ptil Tekhelet strings worldwide. The Talmud describes Tekhelet as a creature descending from the sea called chilazone. Chilazone is described as “similar the sea, like a fish and leaving the sea once every seventy years. Chilazon has a meaning of "snail" in Hebrew.
Murex snails own the gland in which the source of Tekhelet is located. Dibromindigo, rising from the ferruginous excretion of a fresh snail, chemically binds to wool when introduced into the solution in a reduced state. In the presence of sunlight, dibromindigo turns into indigo, leaving the color of a fast-blue wool.
Ptil Tekhelet ensures genuine Ptil Tekhelet strings so Jews, one more time, are able to execute the mitzvah of wearing Tekhelet on their Tzitzit. The technology of the process of extraction of paint for the manufacture of Tekhelet is long lost.
Wearing tekhelt on tzitzite is a mitzvah enjoined by the Torah. This commandment is intended for all generations, no matter where being situated. Only during the last century people understood the deep meaning and privilege to begin the restoration of Tekhelet, which people have been denied for many centuries.
In order to get paint from a purple snail, there is need to break its pretty massive shell. Then get to the gland, which produces a special clear liquid.