Cooker books always say not to use metal lids on jars of chutney, but I never paid any notice and it has never caused any issues. Until now.
At lunchtime, I go to get some more chutney from the attic and find myself at the bottom of the box with three almost empty jars. The contents have desiccated since 2014 when I made the damson chutney. I figure that the seals have failed, but Nick discovers that the lids have rusted through.
I started using plastic lids last year, so problem solved.