455. The Wool Used for Tzitzis

Tzitzis 1:10

Both the white strings and the techeiles may be made out of interwoven strings. Even a string made of eight interwoven threads is considered a single string vis-à-vis tzitzis.

Tzitzis 1:11

Both the white strings and the techeiles must be spun with the intention that they will be used for the mitzvah of tzitzis. Tzitzis may not be made from the wool that got stuck on thorns when the sheep graze, nor from hair that got pulled off the animal, nor from the strands remaining on the loom after the weaver finishes a garment. They must be made from wool that was shorn, or from flax. Tzitzis may not be made from stolen wool, from wool taken from a condemned city, or from the wool of a consecrated animal. If such wool was used, the tzitzis are invalid. If somebody bowed down to an animal, its wool may not be used for tzitzis. If someone bowed down to planted flax, tzitzis made from it are valid because the flax undergoes a transformation.