1. Halachos of קינוח הפה and other procedures required to eat meat after dairy

The previous Daf taught that one who ate dairy and wishes to eat meat must first perform נטילת ידים – washing his hands and קינוח הפה – wiping out his mouth. Beis Hillel says מדיח – he must rinse his mouth, and the Gemara clarifies that this is in addition to קינוח הפה, not instead. Rebbe Zeira says that קינוח הפה may only be performed with bread; furthermore, it must be wheat, not barley (which crumbles when eaten, and does not effectively clean out his mouth). It cannot be hot bread (which sticks to one’s mouth), nor hard (which crumbles when eaten). However, the Gemara concludes: והלכתא בכל מילי הוי קינוח – the halachah is that wiping can be performed with any [food], except for flour, dates, and vegetables. Rav Assi asked Rebbe Yochanan how long one must wait after eating dairy before he may eat meat, and he replied: ולא כלום – not at all.

1. Eating dairy after meat

Rav Chisda said: אכל בשר אסור לאכול גבינה – if one ate meat, he may not eat dairy afterwards (Rashi explains that fatty residue clings to his mouth, causing meat flavor to remain). After eating dairy, however, one may eat meat (once he wipes and rinses his mouth, and washes his hands). Rav Acha bar Yosef asked Rav Chisda: בשר שבין השינים מהו – what is the halachah of meat stuck between the teeth? Does it still have the status of “meat”? Rav Chisda replied with a passuk: הבשר עודנו בין שיניהם – the meat was still between their teeth, proving this is still considered “meat.” Mar Ukva said: אנא להא מלתא חלא בר חמרא לגבי אבא – Regarding this matter, I am like vinegar the son of wine compared to my father: for when my father would eat meat, he would not eat cheese until the same time the next day (twenty-four hours later), whereas when I eat meat, בהא סעודתא הוא דלא אכילנא – it is only in this same meal that I do not eat cheese, לסעודתא אחריתא אכילנא – but in the next meal, I do eat cheese.

1. Laws of מים ראשונים and מים אחרונים

Rav Yitzchak bar Ashyan said: מים ראשונים מצוה – the “first waters” for washing before eating bread are a mitzvah, ואחרונים חובה – but the “last [waters]” for washing before ברכת המזון are an obligation. A Baraisa calls both a "חובה", relative to "אמצעיים" – middle [waters] between courses, which are רשות – optional. מים ראשונים may be poured into a כלי or onto the ground, but מים אחרונים must be poured into a כלי; other say it may not be poured onto the ground (the difference being whether they may be poured onto קינסא – wood chips). They cannot be poured on the ground because a רוח רעה – evil spirit rests on them. מים ראשונים may be performed with hot or cold water, but מים אחרונים must be with cold water, because hot water softens the hands and does not remove residue. Rebbe Yannai said one may wash with water שאין היד סולדת בהן – that the hand would not be scalded by them, but not with water which is יד סולדת בהן. There are two versions if this distinction was made regarding מים ראשונים, or מים אחרונים.

מים אחרונים is an obligation because of מלח סדומית – “Sodom salt,” which blinds the eyes, of which one grain is found in a כור of normal salt.