Fill the bottom layer of a 3-piece steamer with water. Put washed grapes in the top of the steamer. Cover with lid. Cook on medium heat on stovetop until juice starts to accumulate in the middle portion of the steamer.
When enough juice has accumulated to fill a jar, hold a canning jar with an oven mitt under the drain valve on the center portion of the steamer. (Or alternatively, put the jar on a stool below the steamer so that the hose reaches into the jar.) Open the value and allow juice to fill jar. Leave 1/4 inch headspace for pints and quarts.
Continue steaming the grapes to remove all the juice, and fill jars as juice accumulates. Frequently and carefully check the bottom layer of the steamer to refill water as needed.
Process jars in a boiling water bath for five minutes.
1 bushel grapes makes 15-20 quarts concentrated juice. Drink concentrated, or dilute with water or seltzer and sweeten to taste.
Place one to two cups grapes in a quart jar and add ½ cup sugar. Fill the jar with hot water, seal, and process in boiling water bath for 5 minutes.
1 bushel grapes makes 50-75 quarts dilute juice. Not as rich of flavor as the concentrate made from the kettle or steamer method, but much faster and less mess.
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.