Why on earth do you think you should allow the jar to cool? The ONLY safe way is to tighten the lid immediately the jam is placed in the jar - certainly in less than about 20 seconds. That way there will be no live microbes or spores and a vacuum will be formed which is broken when the jar is first opened. I've been making jam for 25+ years and kept some as long as 8 years before opening - without problems. DO NOT EVER let the jars cool before sealing them. Also, the idea of putting a piece of greaseproof paper over the top of the jam was fine in the old days when tops were not sealable, but we now have little rubber pieces set into the tops so the jars can be sealed with certainty. When the top indents slightly a short while after bottling (or the safety button clicks inwards), it shows that the vacuum has been formed and the jar can be stored for years in the cupboard. However, refrigeration is advised after opening. It is really dangerous to advise people to allow the jars to cool before adding the lid as microbes and spores can enter and thrive. When filling jars (I do four kilos of fruit in each batch), I use a JAM FUNNEL (about a fiver) and use a large ladle to fill a Pyrex jug (a measuring jug, actually) then fill about six jars at a time before putting the lids on. You will need to top up the jars after removing the funnel but ensure the jar top is clean, wiping if necessary, then hold the jars with a cloth whilst lidding. See me at www.XYLTH.com - 04 Oct 2013