To extract grape juice, put the grapes into a saucepan and add 1/2-3/4 cup water.

Bring the mixture to a boil while mashing the grapes. Cook until the grapes completely are soft and fall apart, about 10 minutes.

Remove from heat and strain through a double layer of cheesecloth. Allow the juice to strain for at least 1 hour.

Refrigerate the juice overnight to allow tartrate crystals to separate out (not all grapes produce crystals)

Strain the cold juice through the cheesecloth again to remove te crystals. Pour carefully, and leave the tartrate crystal sediment behind at the bottom of the jar.

Add 4 cups of grape juice to a large heavy-bottomed saucepan. Add the powdered pectin and stir to dissolve.

Bring the mixture to a boil over high heat for 1 minute.

Add the sugar and stir to dissolve. Bring the mixture back to a hard boil and boil 1 minute. Turn off the heat.

Ladle the grape jelly into prepared jars, store according to one of the methods above.