Wax circles for jam necessary?

[selfraising]

Do I need to use wax circles for jam and why are they used if you do?

[smallblueplanet]

Used them once, the top of the jam went mouldy where they touched - never again...

[Alison]

I always use them, the wax bit forms a bit of a seal at the jar and they stop any condensation from the lid causing mould on the jam. Never had any jam go mouldy with them, even when I've stored it for 2 or 3 years.

[SarzWix]

I stopped using them when I entered a jar of jelly into the show, and the judge stuck the spoon straight through the wax circle without noticing it! In fact, they aren't really necessary unless you're using cellophane circles and rubber bands instead of proper lids.

[pipkins]

Thanks for that handy hint!!

[selfraising]

Thanks everyone, so if I use the screw on lids, the wax discs are not necessary. Another daft question from a newbie jam maker.....does it matter if the wax discs are a smaller diameter than the jam in the jar?