Eli5, why do Mason jar lids typically come in 2 parts, threads and seal, as opposed to nearly every other commonly used household container?
In: 7899
It’s not just a container, it’s made for canning. They do sell one-piece plastic screw-on lids if you’re just using it as a container. But if you’re canning you use the two-piece as such:
* Put stuff in jar
* Put on lid and loosely screw on the ring so that it’s just keeping the lid on
* Heat the jar, usually by boiling, which will heat contents and create steam under the lid, which escapes from the snug-but-not-tight seal. This also kills the bad bugs.
* Remove from heat and tighten the ring to press lid against jar
* After jar cools down, the steam condenses, and there will be suction against the lid if you’ve done it right (overfilling is a common reason you didn’t).
* You can now remove the ring and reuse it.
* Months or even years later when you open the jar and break the suction, you can use a ring to seal the lid against it again when in the refrigerator. Or you replace it with a plastic screw top.
* Discard the lid when you’re finished because it may not seal right if used again
And the whole time you’re doing this you’re going to feel like a surgeon because you have to keep everything sterile, like boiling the jars, lids, and rings before you use them, and not touching the lids or insides of rings with your hands. They make a nice stick with a flat magnet on it to help pick up the lids and set them on the jars.
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