If like me you no longer have lids...well some of my jars are over 10 yrs
old.........just cut squares of cling film, then as soon as you have filled
the jars (Making sure the top of the jar is DRY and clean then apply the
cling film, as the jam cools the film will pull in tighter sometimes it will
dip a good half inch into the jar.
I have kept some for 3 years + this way.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk