My annual batch of marmalade turned out a bit odd - I noticed that there seemed to be more of it than usual (I needed to prep a couple more jars). Then, when I opened the first jar, I found it was looser than usual - it held a set until I'd got about halfway down the jar, but after that I needed to spoon it out. I guess I stopped boiling a bit too soon.
Still, the flavour was good, so I put up with it through a couple of jars. The third jar I opened had a huge mat of mould on the top, mostly but not entirely on the greaseproof paper; I checked and found the same was true of about half the remaining jars. Considering that they'd only been there a couple of months, this seemed less than ideal - so, what with this and the loose set, I thought that Something should be Done, and set about reboiling eight jars' worth of marmalade.
Delia's recipe doesn't give specific instructions for timing a repeat boil, so I went back to the original instructions - "Bring it to a really fast boil, and boil for ten minutes" or WTTE. After ten minutes I tried the 'push test' but didn't see any crinkling on the skin of the jam - in fact there wasn't a skin to speak of, it just seemed to be setting into a solid blob. I gave it another five minutes and tried again with the same result, then gave up and left it to cool.
This resulted in five jars of marmalade - very dark marmalade. Very dark and, it turned out, very solid; pretty much the constituency of rubber.
Can I rescue it, at least as far as the consistency's concerned? (Some of the sugar's clearly burned and isn't going to un-burn.) If I did extract it from the jars and boil it up again with added water, how would I know how much water to add - and, crucially, when to stop boiling?