May one activate a glow stick on Shabbos? (In other words, is there a prohibition on activating the chemical reaction which produces the light in a glow stick?)


5 Answers 5


I hope that this is more helpful.

I am a rabbi in Birmingham. When we have tornadoes which knock out power we recommend people use light sticks. There is no heat generated, the light is a simple chemical reaction. breaking the inner glass is not mekalkel as what you are doing is not destructive it is in fact constructive. Think of cutting a cucumber for salad...yeah you are breaking something but it is for a constructive purpose so it is not mekalkel.

Not every cutting act or breaking act is forbidden. It must fit into a category of melakha. The three categories of cutting are Gozez and Kore'a and mekhatech.

Gozez requires that the cutting be done inorder to improve the item that it is being cut off from the av melakha only applies in animals and people but the toladot apply globally (bekhorot 24b, tosafot bekhorot 25a, Eglei Tal Melekhet Gozez). This is shearing a sheep or getting a hair cut.

Koreya: requires that the tearing be done inorder to sew back. This means that if you have two pieces of cloth that are coming apart you may not separate them so that you can resew them. This melakha only applies to soft bendable materials (cloth etc.) and not to things like metal or wood or glass (minhat chinuch shabbat 24 and elsewhere I cant remember or find at the moment) and though not the main stream view may pasken that it only applies to woven materials.

Mekhatekh, this only applies when cutting something to a specific size or shape (rambam 11, chayei adam)

The category of breaking is only applicable if you in the process do a melakha. Or if it is destroying inorder to build however, if there is no constructive nature to the act there is no issur (maybe baal tashchit though it wouldnt apply in this case) The gemara posits that even if a man is breaking something inorder to show his anger in his household that may not be completely non-constructive.

All this being said, I dont let my children play with the light sticks on shabbat and we don't take them out unless there is a power outage. I dont think that it would be assur for them to do so but I dont think that it is shabbostik (it is not in the spirit of shabbat). In the case that you really need them for light it is certainly better than any alternative such as a flashlight. So in summary I think that it is permitted but I think that it lessens the shabbat experience (except for when it doesn't)

  • 4
    But aren't the rules for cutting/breaking food different than for other purposes? If breaking the glass tube is, as you say, a constructive act (which it may well be, since you intend to do so and are benefiting from it), then that would be a melachah de'oraisa. Anyway, though, welcome to J.SE!
    – Alex
    Mar 18, 2012 at 14:04
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    Eytan Yammer, welcome to Judaism.SE, and thanks very much for sharing your on-the-ground experience! Your answer would be even more valuable if you'd edit in some of the reasoning you've put forth in the above comments, as well as any relevant sources. Also, please consider registering your account, which will give you access to more of the site's features.
    – Isaac Moses
    Mar 18, 2012 at 14:34
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    its only M"Bp if the action is the final act of creating an item and that in general the action is preformed by the artisan who does it. Additionally it may not apply to most keilim (tosafot) It is more likely that cleaning glassed is M"Bp as that is the last thing the optician does before handing over the pair of glasses. the way one uses an item cannot be M"Bp if it were it would be assur to use any item in your house. It is a light stick before you snap it is not broken and it is no more a light stick after you snap it. Is using plastic dishes M"Bp on the plastic plates? of course not Mar 18, 2012 at 16:30
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    i'm not following your logic. why is everything in my house assur? you don't use a light stick by cracking it; you use it by holding it and seeing things in the dark. the rule that the way you use it is not mbp is for things that you do and undo and redo normally, not one time things that prepare a product for use and re-use. using the paper plates is not mbp, but separating plasticware that is attached from the factory and was accidentally never cut may be mbp. consider also the plastic ring attached to the bottom of a bottle cap: breaking that off may be mbp according to some poskim.
    – Double AA
    Mar 18, 2012 at 16:45
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    And bekvod harav, i think that the halachik instincts of talmidei chachamim are valuable in terms of psak. a rabbi who has a feeling about something can be an indication of how he conceptually views the issur in question and that is exactly the side he will paskin like. so chazal didn't paskin according to your feelings, but you do, and they did according to theirs.
    – Double AA
    Mar 18, 2012 at 16:48

Aside from the chemical reaction (about which I don't know whether that would be permissible on Shabbos), there is also the fact that in activating it you're breaking the inner glass tube. At the very least, if we consider this מקלקל (a destructive act), then I would think it would be prohibited Rabbinically.


It's discussed by Rabbi Mordechai Torczyner, along with the chemical reaction causing self-heating meals, in this mp3. (Also see his source sheet.) It's been discussed in some Hebrew-language halacha journals recently.

It appears to be at most rabbinically prohibited, at least at first glance.

  • At first glance you would think that it is only rabbinically prohibited? But perhaps it could be considered as within the category of makeh be-patish? Jun 27, 2012 at 15:06

Rabbi Nachum Rabinowitz talks about this in Techumin vol 13. He goes into it a bit (fire/nolad/מתקן מנא), and ultimately concludes that he doesn't see any reason for this to be assur and then explicitly permits it for soldiers/emergency lighting.


The Rivevos Ephraim 7:104:2 was asked about a stick light(glow stick) which have two main concerns. Is there an issue of fire here and is there an issue of nolad. The questioner believes that there is no fire aspect ,and is only concerned for he issur of nolad. The Rivevos Ephraim answered that it should be mutar in cases of emergency since nolad is not applicable in a case of possible danger to life.

Text of the Rivevos Ephraim's answer:

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