Translation:Shulchan Aruch/Yoreh Deah/121
One who acquires old (used) dishes from a non-Jew, he should kasher the dishes according to the manner in which the dishes were used (by the non-Jew). Thus, someone who takes a used dish which had been used for cold items, such as cups or flasks and similar things, should rinse them, and one needs to rub them well in water during the washing in order to remove and cleanse the forbidden things that are on them. And afterwards, one should rinse them in water and immerse them (in a mikveh) and they are permissible. Gloss: 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.
If one took from them [non-Jews] dishes which were used for hot things, whether the dishes are metal or they are wood or stone, they should be purged (via boiling), and then immersed (in a mikveh) if they are metal, and they are permitted. And if one immersed them and then boiled them, they are permitted. And there are those who say that you would need to go back and immerse them again. Gloss: If they are dishes made of bone, see in the laws of Passover (Siman 451). 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.
The laws of boiling and cleansing (purification, literally: whitening) are written in the laws of Passover.
A pan in which one fries, even though with regard to hametz on pesach it is enough to purge it (via boiling) it, with regard to all other forbidden things, it requires “whitening.”
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]. And even to cut a spicy/sharp substance with the knife, such as a radish, the above procedure is sufficient. Rema: And to use the knife in a more permanent manner, it is no less than other vessels that we have the practice to kasher with boiling water even for [cutting] a cold substance. [However,] if the knife has nicks in it or one wants to use it to cut hot substances or to ritually slaughter an animal with it, then one must kasher it with fire or sharpen it well over the whole surface of the knife, on the type of knife-sharpener that is used by glass-blowers. Rema: There are those who say that merely sharpening the knife only works for cutting cold substances, but not for hot substances, and this is how we practice ideally. However, if one is unable to kasher the knife with fire well because of the handle, then one should kasher it with fire and then kasher it [again] with boiling water afterwards. However, if one koshered the knife with fire and didn’t kasher it [again] with boiling water, even if there are nicks in it,or if one kashered it with boiling water and did not kasher it [again] with fire and there are no nicks in it, and one cut hot food with it, the food is not forbidden, even if the knife is ben yoma. And if one sharpened the knife well on every part of if on a knife-sharpener, and then kashered it with boiling water afterwards this is sufficient, even ab initio just like kashering with fire when one is able to clean the nicks in it.