A friend told me that his family will kasher his microwave in general (ie if non-kosher food was heated up in it) but will not kasher it for Pesach, letting it lie dormant instead. Does anyone have a source for such a distinction? (Let's also assume the tray can be covered, so the issue is only with the microwave itself.)

I know people are generally overly machmir (stringent) when it comes to chametz. I'm looking for a source for this particular distinction.

  • Re: the tray -- it's not that easy to cover. You certainly can't do so with tinfoil. Most people (I think) just get rid of the tray, which you don't actually need, or buy a new one for Pesach
    – SAH
    Aug 29, 2017 at 1:09
  • I know that per Maran Yosef Qaro the concept of eino ben yomo applies to Pesah and therefore if one let's the microwave lie dormant for more than a day then food from it can be eaten during Pesah.
    – Aaron
    Nov 4, 2018 at 16:55

1 Answer 1


You wanted to know, why some people might be machmir on this:

From InstituteforDayanim.com

Kashering a microwave for Pesach is impossible since only metal or wood can be kashered for Pesach. Although one can kasher plastic the rest of the year, one should not do so for Pesach. The inside of a microwave is generally not metal and is thus not kasherable.

It goes on to give a method to test if the microwave has absorbed any ta'am (even lifgam), and if it hasn't, it says it may be used. However, this that it can't be kashered, and that the only way to use it is if you're sure it hasn't absorbed anything, may be why some are machmir.

From teach613.org

Although many people will not kasher a microwave for Pesach because it has plastic components and because it is hard to clean properly, if you choose to kasher it the process is as follows. ...

(Plastic can not be kashered for Pesach.)

  • 1
    Intersting. I wonder why they limit it to metal and wood? I know the Rama is machmir by glass, but that doesn't necasarily set the general rule.
    – Double AA
    Mar 15, 2012 at 3:15
  • @DoubleAA At the bottom of this Star-K article it gives a list of materials that can't be kashered for Pesach. Among them, porcelain, stoneware, and plastic.
    – HodofHod
    Mar 15, 2012 at 3:22
  • 2
    Hmmm...You've presented particularly perplexing passover pottery precepts! I will have to look into this further. Thanks!
    – Double AA
    Mar 15, 2012 at 3:26
  • @DoubleAA The second link I just edited in says that you can kasher stone for Pesach. Either way, this is certainly a good reason for some to be nervous about using microwaves.
    – HodofHod
    Mar 15, 2012 at 3:30
  • First link is dead.
    – Double AA
    Apr 11, 2016 at 3:24

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