A friend offered to give me some plastic bottles to reuse. I wasn't sure whether they were suitable for jam making, though I have bought jam in plastic bottles. I decided that the only way to know for sure was to try it. I could end up with a mucky mess and lose a spoonful of jam, but I'd know!
I've been making rhubarb jam this morning. I washed the plastic bottle along with a couple of glass ones, put it in to the oven to heat up with the others and put the plastic lid into boiling water to heat. I put a spoonful of the cooked jam in, waited a minute, all good, so I filled the jar and put the lid on. So far, so good, though I'll leave the jar to get cold before I move it again.
The rhubarb jam is a wonderful deep pink colour and has a nice tart taste. Here's the recipe here.