In article ,
"David Hare-Scott" wrote:

The vacola system is quite simple. The jar has a shallow slot around the
top. You stretch an annular rubber seal into that slot. You then pack the
jar and put a metal lid on it that sits on the rubber seal. You add a metal
clip that holds the lid down tight and process in the normal way. When cool
you take the clip off. The lid now magically stays on as the processing
drives out the air from the jar but as it cools the seal prevents it from
re-entering. So you have a sterile vacuum sealed jar. In the case of fruit
it will last for years.

ie (and hardly surprisingly) fundamentally similar to the ball-jar
method, except that the seal is separate, rather than fused to the (for
ball jars, "use once, per official guidelines") metal lid. The function
of the vacola clip is served by the threaded ring on ball-jars.

Harking back to the all glass jars with glass lids and separate jar
rubber rings, which I have a bunch of but don't use for canning
(officaldom's concern with those is that one might not find a failed
seal as obvious, since glass lids don't "pop" in as the metal ones do
when sealed.) I have relegated mine to dry storage duty.

I have canned meat exactly once, to make "real mincemeat" - and that's
the only thing that would lead me to can meat (and hasn't for 25
years...)

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