פירוש על עבודה זרה 150:25

Here we learn how to kasher wicker-baskets and strainers.

The am ha’aretz is assumed to be impure. According to one opinion, when he touches only one cluster we only have to treat as impure only those clusters that are around it. But according to the other opinion, we must treat the entire winepress as impure.

The Talmud raises a contradiction between the one who says that only the surrounding clusters are impure and a mishnah which assumes that if a sheretz (a reptile of sorts) falls into an oil-mill and there is flowing liquid which would convey the impurity throughout the mill the entire mill is impure. Isn’t there liquid in the winepress as well? The answer is that the clusters will stop the liquid from flowing all the way around. The liquid will only reach the close clusters. Therefore, only they are impure. Whereas the olives are not clusters and will not stop the flow of the oil.

The rabbis rule according to the lenient viewpoint—only the cluster and all that around it is impure.

The general principle in this mishnah is quite simple: the way that a utensil was normally used is the way that it is made usable by the Jew. A utensil that was used generally with cold foods may be washed off and it is kosher. Since it was used with cold, it did not absorb the unkosher food and therefore it need only be cleaned with water. If a utensil had been used with hot boiling liquids, such as a soup pot, it absorbed more than the utensil used with cold. Therefore it must be dipped in boiling water to remove the unkosher elements that it has absorbed. Utensils that had been used directly on the fire, such as the spit and the grill, become even more absorbent. The only way to kasher them is to make them white hot. A knife is a special case: it must be polished so that the outside layer of the knife is actually removed. This is because the knife, which is pressed with force into foods, tends to become more absorbent, even though it is not used directly on the fire. Remember that the knives in those days were not made of the hard stainless steel of which our knives are made.

The Talmud adds that in addition to “kashering” all of these vessels need to be immersed in a mikveh.

Rava derives this requirement from the additional word “וטהר” found at the end of the verse. This word is extraneous, so Rava uses it as the source for the requirement of immersing vessels bought from non-Jews.

Bar Kapara derives the halakhah that vessels bought from a Gentile must be immersed in the mikveh from the use of the word “the waters of lustration” which literally translates as “the waters of the menstruant (niddah). Just as a menstruant must immerse in a mikveh, so too must these vessels be immersed in the mikveh.

The Talmud now explains why we need both Rava and Bar Kapara’s midrash. Don’t they teach the same thing? If we only had the midrash on “it shall be clean” I would not have known that the immersion needs to be in a mikveh. The cleansing could have been accomplished by pouring water over the person. Thus we need the verse that compares the method of immersion for vessels to that needed by a niddah. And if we only had the verse that mentions the mikveh (“waters of lustration”) I might have thought that the purity laws of immersing Gentile vessels are the same as those for a niddah—they are not pure until the sun sets. Therefore, the other verse is necessary to teach that the vessels are immediately pure even before the sun sets.

R. Nahman says that even new vessels, those never used and therefore that have not absorbed the taste of any prohibited food, must be immersed. He derives this from the fact that immersion is required even if the vessels were first kashered by fire (which is mentioned in the biblical passage). Such cleansing will utterly rid the vessel of any taste and make it like new. Nevertheless, it must be immersed. From here we can conclude that all vessels bought from non-Jews must be immersed.

If even vessels that have no residue of taste in them must be immersed, then why not say that even scissors need to be immersed? R. Nahman answered that the only types of vessels mentioned in the biblical passage are those used in connection with meals. Shearing scissors are not included.

In the biblical passage from which these laws are derived, the Israelites had acquired title to the utensils (they took them as booty in war). Possession means that they must be immersed. But if one borrows the vessels, they need not be immersed.
We should note that there is something a bit strange in this law. If the requirement has to do with purity or with kashrut, then what should it matter if the vessel was bought or borrowed?

R. Yohanan explains that only metal utensils were mentioned in the passage and therefore only they must be immersed. Those made of earth and dung need not.

Glassware can be repaired, and was indeed repaired, in a world in which glassware was very expensive, and is thus like metal. Just as metal utensils must be immersed, so must glassware.

Glazed utensils before they are glazed are basically just earthenware and earthenware vessels need not be immersed. But by the end, they are like glass and glass vessels must be immersed. So there is a dispute as to whether they need immersion like glass utensils, or not like earthenware. The rule is that they do.

The Talmud asks whether Jews have to immerse a vessel if the non-Jew gave it to them as a pledge, which would ostensibly be returned to the non-Jew upon termination of the loan. Mar bar R. Ashi, one of the last amoraim, teaches that indeed his father did immerse such a vessel. However, he is not sure if this is because a vessel taken as a pledge is considered to be the property of the creditor (this is a question frequently asked in the Talmud). If this was true, then taking a pledge is just like buying. Or perhaps in this particular case R. Ashi assumed that the non-Jew was not going to take it back but in other cases, where the non-Jew might take it back, it would not be considered as belonging to the creditor and therefore the Jew would not have to immerse it.

This baraita provides all the rules for how to make vessels that can be kashered (metal vessels, mostly) usable by a Jew. They all need to be immersed, and depending on how they were used, this is how they need to be kashered. Note that many of these rules will be familiar to anyone who ever kashered anything for Pesah.

There is a dispute if the Jew uses the vessel before it was kashered. According to one opinion, the contents cooked or prepared in the vessel are prohibited. This accords with the opinion that if a forbidden element imparts a worsened flavor the food is permitted. The non-Jew’s vessel will emit the flavor embedded in the vessel but this flavor is old and will not improve the taste of the dish. Nevertheless, this opinion holds, the forbidden element causes a prohibition.
According to the other opinion, the food is permitted because he holds that if the forbidden element imparts a worsened flavor, the dish is permitted.

The Talmud asks—if one opinion holds that when it imparts a worsened flavor the food is permitted, how did the Torah ever prohibit vessels used by non-Jews. The answer is that this prohibition only applies to vessels used that very day—in this case, the taste imparted is not considered to be a worsening flavor.