My advice to you, folks: never underestimate the experience needed for making jam, or the time. What happened was that I found an abandoned blackcurrant bush not far from our house and, as wild berries in Uppsala is so much rarer than wild blackberries is in Brighton (which grow almost everywhere), I was very happy. I wanted to do something with my blackcurrants and decided on jam, which I have done before but always in the same experimental way.
Everything went fine. The whole kitchen smelled from warm berries, until a more unpleasant smell became evident, burnt rubber. To save time I had put both glass jars, and the rubber rings to go with them, on 300 degrees Celsius in the oven to sterilize them (normally you sterilize them in boiling water, I thought I was smart). I managed to get the rubber rings out from the oven and opened all the windows to let the smell out. Luckily I had not burnt the jam in the meantime. Next I got the, by now very hot, glass jars out of the oven. They were ready to be filled, I thought. However when putting the glass down on the wet sink they both, slowly and painfully started to crack before my eyes until the hole glass was painted with cracks. Those where the only two glass jars I had at home, what now? In the end I had to take an empty tea container, which I sterilized in water this time, and finally managed to put the finished jam in. And… well in the end I hope some summer blackcurrant jam in the cold winter days will be worth the effort.