I will use Welch’s grape jelly for this example. But you can use any juice that you’d like.
First freeze a little saucer in your freezer. You will need it later.
Use five cups of Welch’s grape juice. 7 cups of sugar. 8 tablespoons of pectin. (Can mix juices if you’d like.)
First add one cup of the sugar to the juice and boil it. Then add a half stick of butter which keeps it clear. In another bowl add the rest of your sugar with the pectin mixed in it which stops the pectin from lumping. Add that into your pot with the juice and bring it slowly to a rolling boil. Rolling boil means that it will begin to bubble with thousands of little bubbles. It will not set properly for you unless you do this last step – boiling until it bubbles. I have learned through my mistakes that you are supposed to boil it as though you are making candy. People say a rolling boil and I say ‘a candy boil’ which means by that time it is extremely hot. Do not get it on your skin!
After you do that, place a teaspoon of it on a frozen plate or saucer that you had in the freezer. If it does not run off of the saucer quickly then that means you have done it properly. If it runs off of the saucer too quickly reboil your mixture. That means there’s too much water in it and you have to boil it away.
Ladle it into your jars. Process in your water bath canner that has something in the bottom to stop the jars from rattling and possibly breaking, for 20 minutes. Turn off the heat and let them set about 5 or 10 minutes. That way the jars won’t break when they come out into the cooler temperature of your room. Place them on a dish towel or something of the sort.
Listen for the lids to ping and when you hear that and the bubble in the middle of the lids have gone flat, you did good. Give it 24 hours and if the bubbles in the middle of your lids have not gone down you can reprocess which means reboil and reprocess the jelly or place it in refrigerator for you and your family to eat.
I have also experienced where people do not even do the water bath canning process. Once they are through they set them on the shelves and they literally jell themselves.
Disclaimer: I am not to be responsible for any odd results when trying this recipe.