In previous Halachot, we have explained that vessels purchased from a non-Jew, such as those produced outside of Israel, require immersion in a Mikveh before using them. We have also discussed which types of vessels require immersion and which do not. We shall now continue discussing this topic.
Regarding plastic vessels, we have already mentioned in previous Halachot that the reason earthenware and clay vessels are exempt from immersion is because when the Torah discusses this obligation in reference to the vessels of Midyan, only metal vessels were included in this commandment. The Gemara tells us that Rav Ashe says that since when glass is broken, it may be repaired by melting it down and forming it into a vessel, it shares the same law as metals. We see then that according to our Sages, glass vessels must likewise be immersed. Based on this, it would seem that the same should apply to plastic vessels; since they can be melted down and formed into vessels, they should be comparable to glass and require immersion in a Mikveh.
Nevertheless, Maran Rabbeinu Ovadia Yosef zt”l writes that since glass only requires immersion by virtue of a rabbinic enactment and not by Torah law, only a substance that existed during the times of our Sages can be included in the enactment requiring them to be immersed. Plastic, however, which did not yet exist in the times of our Sages cannot be included in this enactment although they are indeed similar to glass vessels in this aspect. On the other hand, Hagaon Harav Yitzchak Yaakov Weiss zt”l, head of the rabbinical court of the Eidah Ha’Charedit, rules in his responsa that plastic vessels indeed require immersion. Nonetheless, he later writes (in his Responsa Minchat Yitzchak, Volume 4) that after seeing the opinion of Maran zt”l, he has changed his mind and now rules in accordance with Maran zt”l that plastic vessels do not require immersion in a Mikveh and they may be used immediately after purchasing them.
Regarding porcelain vessels and dishes, the Sefer Kenesset Ha’Gedolah (authored by Hagaon Harav Chaim Benbenishti zt”l, pupil of Hagon Harav Yosef of Tarani, who lived approximately four-hundred years ago) writes that the custom is to absolve them of immersion, for only vessels which are actually glass and are able to be repaired by melting them down and forming them into vessels require immersion since they are similar to metals; however, since porcelain vessels cannot be repaired once they are broken, they are similar to wooden and earthenware vessels which do not require immersion.
Therefore, porcelain vessels (i.e. genuine porcelain; not all glazed earthenware or china vessels or dishes are considered porcelain) do not require immersion and one may be lenient and use them immediately after buying them.
In the next Halacha, we shall discuss the laws of disposable vessels.