Producing Tekhelet-dyed tzitzit from sheep to string is a complicated process. The steps are actually outlined in the Mishna’s discussion of the types of work prohibited on Shabbat.

• Shearing (Gozez – גוזז): The wool is shorn from the sheep
• Bleaching (Libun – ליבון): Treating the raw wool with chemicals to whiten it
• Dyeing (Tzviah – צביעה): Dipping the wool into the Tekhelet dye vat
• Carding (Niputz – ניפוץ): Combing the wool to straighten the fibers
• Spinning (Teviyah – טוויה): Simultaneously twisting the wool and pulling it into threads
• Plying (Shezira – שזירה): 8 threads are wound together tightly to form a string

After the shezira, the strings are placed into hot steam to fix them so that they won’t unravel. They can then be cut to the desired length and tied onto the garment.

The dyeing, spinning and plying must all be done with the proper intention (l’shma), and are therefore done by hand. An additional stringency is to include the carding in that category (niputz l’shma).