Put washed grapes in a large kettle and crush them. Add only a small amount of water to keep from sticking. Cook the grapes until the skins pop off. Cook at a low boil. Strain the juice, either through cheese cloth bag or a strainer. Put in canning jars and process in a boiling water bath for five minutes.
Sweetener may be added before sealing or when ready to use. Diluting this juice 2 parts juice to 1 part seltzer water with a squeeze of fresh orange makes a refreshing summer drink.
1 bushel grapes makes 15-20 quarts concentrated juice. Dilute to taste.
Good to the last drop: After juice is removed from the cooked grapes, put remaining pulp through a vegetable strainer or push through a fine sieve with a spoon to remove the seeds. Use this thick pulpy juice in Concord jam, pie or tapioca recipes.