huh. apparently the old glass jar sealing stuff is considered unsuitable not because it doesn't work, but because there wasn't really a convenient way to check if the vaccum seal is intact.
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@icedquinn What? The cap is concave if the seal is intact and it pops up when the seal is broken.
I have a jar of zeolite molecular sieves and when I leave it alone for long enough the vacuum created by them sucking moisture out of the air does this.
@swiley they were talking about old (victorian) canning jars.
