Write of Passage Dayan Yosef Greenwald April 15, 2021 Q I sent someone a text…
Excerpted and adapted from a shiur by Rav Moshe Zev Granek
February 25, 2021
The Mishnah (Kilayim 9:1) says that all the bigdei kehunah are made of sheep’s wool, linen, or both together. The Mishnah later says that if one mixed together sheep’s wool and camel’s wool, the status of the thread follows the rov (majority) of the fibers. The context of this halacha is that of kilayim (which only applies to mixing sheep’s wool—not camel’s wool—with linen). Would it also apply to bigdei kehunah, making a blended camel’s wool-sheep’s wool fabric valid as wool if it was majority sheep’s wool?
To resolve this, we need to explain the basis for this halacha. According to the Bais Yosef (based upon his understanding of the Rambam and Smag), this halacha of rov stems from the concept of bitul (nullification), where the majority thread nullifies the minority. But perhaps bitul can only be used to nullify an issur mixed in with heter and render it permitted, but not to provide a required status that an item does not have. Thus, if the bigdei kehunah must be made from sheep’s wool, perhaps a garment with a majority of sheep’s wool does not qualify based on bitul. This issue may be subject to a dispute among the Rishonim (see Kovetz He’aros 59).
According to the Noda Bihuda (Tinyana 186), the halacha of rov concerning linen and wool is not based on bitul, but based on the idea that every fabric has a halachic status. If a majority of the fibers are sheep’s wool, the fabric is classified as sheep’s wool, but if the majority is another material, it isn’t. According to this it would seem that a fabric with a majority of sheep’s wool and a minority of other material would be acceptable for the bigdei kehunah, because the fabric is halachically defined as sheep’s wool.