I have some nice red wine some two years old,and kept in 1 gallon
demijohns with a rubber bung tightly put in at the top.I have heard
that this method of closing the wine is not good,since eventually (on
a hot day for example)the rubber bung starts 'leaking' and letting in
air.In the first year I used an air lock bubbler,and assume this was
fine.Is there an easy way to make sure the demijohn is fully sealed
say by using a piece of plastic between the rubber and glass or would
this leak eventually.I would appreciate some advice.
Regards,Michael

Michael -

A rubber bung with an airlock should make a good seal if it is
inserted firmly. You don't need layers of plastic.

At two years, though, I have to wonder why you don't just bottle the
wine and be done? With airlocks, you need to check them regularly, to
make sure they don't run dry. If you use decent-quality corks, and
store the bottles on their sides, you really shouldn't need to worry
about the wine once it is in the bottle.

Doug