Duchkah D'sakinah [Part 1] (Bitul and Blios #20 - Shulchan Aruch 96:1-3)
Rabbi Dovid Cohen
Duchkah D'sakinah [Part 1] : Levels of absorption; Hadachah, gerairah, shifshuf, klipah; Knives nowadays; Cleaning methods. See seforim by Rabbi Cohen at www.kashrushalacha.com