Yosef Karo

“ Seif 7 An old knife, whether it is large or small, that was acquired from an idol worshipper, if you took it to use with cold substances, then if there are no nicks in it, it should be stuck 10 times in tough (compact) ground and each of the thrusts into the ground should be into tough ground – therefore one should not thrust the knife in the same spot that he thrust it previously – [and then it will be fit for use with the cold substance] . ”

“ There are places where people allowed placing wine in vessels which have their planks glued together with forbidden fat, since it is the nature of wine to run from the forbidden fat. And the forbidden fat congeals and stands by itself and does not touch the wine at all. הלוקח כלים ישנים מן העובד כוכבים -- כדרך שנשתמש בהן העובד כוכבים כך הוא הכשרן. לפיכך הלוקח כלי תשמיש ישנים שנשתמש בהם בצונן, כגון כוסות וצלוחיות וכיוצא בהן -- מדיחן. ”

“ One should not purge any dish so long as it has been used within the past 24 hours (ben yomo) and one should not use the boiling waters [i.e. the water used for kashering should not be used for anything else] . If a dish needs boiling, it is not effective if you chip it away with artists’ tools. And see above in Siman 108 the law of a baker’s shovel that has prohibition on it. לקח מהן כלים שנשתמש בהם בחמין -- בין שהם של מתכת או של עץ או אבן -- מגעילן ואחר כך מטבילן אם הם של מתכת והם מותרים. ”