Last week we discussed some of the opinions concerning opening bags and containers on Shabbos; this week we will discuss the issues related to opening metal cans, such as tuna or soda cans, on Shabbos.
The earliest case discussed by the poskim concerns the opening of sardine cans. The Minchas Shabbos and Tehilah L’Dovid argue that opening sealed sardine cans violates the melocha (forbidden labor) of soteir, destroying.1 However, the Chazon Ish (51:11) suggests that soteir is not relevant here, because one who is opening the can is not trying to destroy it; rather, he is opening it in order to use it as a vessel. Still, the Chazon Ish maintains that it is forbidden to open them for another reason. Since many people reuse these cans for other items, and they therefore become functional vessels once opened, we are concerned that opening them might violate the prohibition of asiyas pesach, making a nice opening in a vessel.
The source of this prohibition is based on the Gemara (Beitzah 33b) that says that breaking a barrel is only permitted in the case of a musteki, an unsturdy and crude container consisting of many pieces of wood glued together, because we are not concerned that one will make a nice opening; according to Rashi’s interpretation there, it would be forbidden to break open a regular barrel because one might make a nice opening in the process, violating the prohibition of tikkun kli (making a vessel).
R’ Binyamin Zilber (Shut Az Nidberu 11:12) adopts this position as well, though he permits opening the can by way of destruction in a time of great need, which does not constitute tikkun kli.
Other poskim take a more lenient approach. R’ Moshe Feinstein (Igros Moshe, Orach Chaim 1:122) argues that opening these cans should, in theory, be permissible since they are comparable to the case in the Shulchan Aruch (314:8, based on Shabbos 146b) of closed baskets used to hold dates, which are permitted to be opened on Shabbos. This is because, as R’ Moshe explains, the baskets are made specifically for the dates and will not be used for anything else afterwards. Therefore, the baskets are batel (subservient) to the dates, and there is no problem of opening them in order to remove the dates. However, as we saw last week regarding the opening of bags that contain food, in practice, R’ Moshe rules that it is forbidden to open this vessel out of the concern that people will come to confuse this with similar cases that are genuinely forbidden.
R’ Yaakov Breisch (Chelkas Yaakov 3:8) employs an argument similar to that of R’ Moshe; however, he entertains the possibility that these cans possibly fall under the category of a musteki, which the Gemara quoted above (Beitzah 33b), permitted to be opened on Shabbos. Therefore, he says we shouldn’t protest to those that open cans on Shabbos, though he suggests that it is better to open the can only halfway, disarming the can of its functional ability.
R' Shlomo Zalman Auerbach (Maor HaShabbos p.490) deals with the case of soda cans, and also rules leniently for the reason cites above – people throw these cans out. He also notes that there is no issue of violating the melocha of mechateich (measured cutting), because one generally doesn’t care where the can opens; it happens to open along the tab, because that is the prefabricated route designed into the can’s design.
Today, since people do not reuse their tuna or sardine cans after the food has been emptied, it is possible that even the Chazon Ish would agree that opening these types of cans is permitted. Nevertheless, some contemporary poskim suggest being stringent, if possible, in order to avoid this question.
We have seen in the past few weeks that minor differences in the manufacturing of various food containers can create major halachik distinctions. Since many of these cases are debated by the poskim, and since the halachik distinctions between the cases are subtle and not always recognized, it is recommended that, ideally, one should open all of the food utensils prior to Shabbos. 1. See Rabbi Joseph Stern’s article on this topic in the RJJ Journal, Spring 1983, p.70.
2. See Rabbi Mordechai Willig’s Am Mordechai al Maseches Shabbos p. 158 for a more detailed analysis of this talmudic passage.
3. Though the Chazon Ish does say that he is not sure whether our case is comparable, even if people don’t keep these cans. See Chelkas Yaakov 3:8:10.
4. See, for example, R’ Ribiat in The 39 Melachos (p.840) and R’ Neustadt in The Weekly Halachic Discussion (p.137).