Introduction:[1]

The following section will deal with the laws of separating through using a filter. In addition to the problems of Borer that are sometimes applicable as will be explained, the prohibition of Miraked may likewise apply, amongst other prohibitions. In essence the prohibitions of Borer and Miraked are really one and the same, being that they are both a separating prohibition. The difference between Miraked and Borer is only with regards to the form of separation. Borer is considered separating from a solid mixture using a sifter to sift out the waste and have the food remain above. Meraked is a prohibition of sifting a solid mixture and having the food fall out and the waste remain above.[2] Regarding a liquid mixture Admur in 319/12[3] rules that straining it and having the sediment remain above may be Borer or Miraked. Thus, by liquid mixtures it is unclear as to which prohibition applies.[4] The reason why this action of separating was split to two different prohibitions is because these were two distinct actions done in the Mishkan and thus were given two different names of prohibition.[5]

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[1] See Gemara Shabbos 73b; 138a; Iglei Tal Zoreh 2-3; Miraked 1; Shevisas Hashabbos Zoreh 2; Toldos Shmuel Zoreh; Tehila Ledavid 319:21; Biur Halacha 319:8 “Meshameres”; Shabbos Kehalacha Vol 2 page 342

[2] Rashi Shabbos 138a; See Shevisas Shabbos ibid; Shabbos Kehalacha ibid

[3] Gemara Shabbos 138a; 138a; So rules also Rambam 8:11; Biur Halacha 319:8 “Meshameres”; Tehila Ledavid 319:21; Shabbos Kehalacha Vol 2 page 342

[4] The reason: The Gemara Shabbos 138a brings a dispute between Rabah and Rebbe Zeira as to which Melacha applies. The Biur Halacha ibid explains that this dispute is only relevant by wine as one does not do an action to the filter, and the filtering happens on its own as one pours the wine through it. However, when one shakes a sifter to separate the waste from the food, then when the food falls below, such as when sifting flour, all agree that the Melacha is Miraked.

^[5] Gemara Shabbos 73b; Shabbos Kehalacha Vol 2 page 342