Thanks for your reply. The lids i'm using are brand new, but without the "popping" function (see picture). I'm new to all this, so didn't realise there was a difference.
I'm really struggling to find anything on the internet about these lids and how to check if they've properly sealed. Do you think that tightening them after they've cooled, could potentially have broken the seal? And if the seal is broken, how long will they keep?
I made my first batch of Rhubarb and Raspberry jam last night and feel a few things went wrong, but am unsure..
Firstly i didn't add enough sugar initially, and therefore had to add more to set it, after already boiling it for at least 20 mins. I didn't use pectin as was determined to try making it without, so forced to add the extra sugar to set. I now worry that i over cooked the fruit and lost its flavour...
Secondly I used standard (boiled) jam jar lids (not the mason kind) to seal the heated jars and turned them upside down to cool. All seemed fine. This morning i decided to check the lids were definitely screwed on properly, using a jar wrench. 7 out of 9 jars made a "popping" sound when tightened and now i worry i've ruined them. Been trying to find an answer online, but all i can see if that people advise against using the jar wrench, however with no reason why.
Can anyone help??