More Discussions for this daf
1. Opening bottle caps 2. Building on Yomtov 3. Making Charcoal on Yom Tov
4. How much commission does a salesman deserve?

Jeff Ram asked:

Dear Rabbi Kornfeld,

Thank you for writing such an informative "Insights" on the halachos of

opening cans, bottles and food containers on Shabbos and Yom Tov.

(Insights to Beitzah 32)

(a) I would appreciate your help in clarifying one point which wasn't clear to me in the article. In Paragraph II (Bottle Caps and screw-off covers) you discuss metal bottle caps which leave a ring behind [sub-paragraph (c)]. Are you talking about the kind of metal caps that we often see on grape juice and "kiddush" wine bottles? If so, I'm not sure I understand the difference between those and the plastic bottle caps we find on the plastic liter bottle of coke.

(b) Also, what do you mean exactly when you say "the cap becomes physically widened or warped...when removed". I couldn't think of any containers (other than corks in bottles of champaigne) where that might be true. Do you have some examples?

Thank you so much (in advance) for your help on these points, and special thanks (again) for that article. It clarified many subtle points regarding halachos that seem to be widely misunderstood.

best regards,

Jeff Ram

The Kollel responds:

Jeff - thanks for your kind words! I'm glad that the essay proved helpful.

(a) Yes, that is the kind of cap that we referred to. The difference between those and the plastic ones is that the metal never came as two separate parts (a top and a ring). When it was placed on the bottle, it was one large piece, that was fitted to the bottle using a shrinking process. Breaking the two apart involve the creation of a new item: a re-usable bottlecap, that did not exist before.

In the case of the plastic bottle caps, the ring is only connected to the top at a few points. It looks like they first put a ring on the bottle, then a cap (which already was usable as a bottlecap as is), and then they melted the two together at certain points by pressing them with a hot piece of metal. Even after being pressed together, they look like two separate parts. In such a case, one is not creating a new bottle cap, but separating a piece of plastic from an already usable bottle cap.

Others have researched the subject, and found that the plastic bottlecaps are also originally one single unit of cap + ring, before they are attached to the bottles. However, they are not attached to the bottles by a shrinking process, but simply by the application of pressure. If so, once again it was a usable bottlecap before being placed on the bottle (since pressure alone, and not physically changing the cap, could attach it to a bottle), and even while on the bottle it is still considered a usable cap (since the bottle could theoretically be "removed from the cap" by crunching it together so that the cap could be removed). Once again, by removing its ring, one has not created a new entity of "bottle cap" that was not in existence previously.

(b) The example that came to mind was the very cap we referred to in your first question -- the grape juice bottle cap. If one does not want to twist it off, one might try to ply it away from the bottle by widening the ring with a knife until it can be removed. Rav Shlomo Zalman does not permit that, since it involves physically changing the bottlecap, which is considered "making" a re-usable cap that was not in existence earlier.

Be well,


Gedalliah asks:

I lost a bunch of stuff, and I guess the bottlecap was one of them. But looking at this answer I wonder why one can crunch a plastic bottle to remove the bottle from the cap, but can't do the same with a glass bottle to remove it from the metal cap?


The Kollel replies:


You can do the same for both. Remember, though, that the issue is not just if you can remove the cap, but if the removed cap is usable as is and can be screwed on to another bottle without first removing the ring under it. Rav Shlomo Zalman prohibits opening the glass bottles with the cap that leaves a ring only because even if you break the bottle, its cap cannot be screwed onto another bottle without first removing its ring.

Be well,