
During this time I realised I had not halved the amount of water like I should have done for the amount of plums so I sieved them, boiled the liquid to reduce it by half.

Then as I was boiling the jam I turned off the oven where I was sterilising my jars and lids and found this had happened: Hee hee! I was running out of jam jars and found this unopened box of jam jars with plastic lids bought years ago and it never occured to me that they would MELT at 120C which is how I always sterilise the jars and lids. My husband thinks I'm an idiot.

Anyway jam tastes nice and no problems reaching setting point, obviously lots of pectin in damsons.
