On Sun, 8 Sep 2013 11:14:47 +0100, Janet wrote:

I have a jug of hard paraffin wax which I use and reuse on the odd

What a faff!

Quite. And withouta proper lid how do you keep the jam once opened?

I use a waxed paper disc ...

What a faff!

... old lids can be cleaned boiled and re-used,

That's what we do saves having to fish the bit of paper out that
serves no useful purpose IMHO. Check the old lids for damage (dents
or distorted seal) then still boiling jam into hot jars and lid on
straight away. Oven mits essential and there may still be a bit ouch
ouch ouch once you've done a few and the heat is starting to
penetrate the mits...

Note this is jam, high sugar. For low sugar or low acidity stuff you
need do need to take more care, ie above boiling point for "a while"
where "a while" is 10 mins.

--
Cheers
Dave.