Old-Fashioned Grape Jelly

Using about 1/4 firm ripe and 3/4 fully ripe grapes, sort, wash and remove stems. Place grapes in a large deep saucepan; crush with a potato masher and add water. Cover and bring to boil over high heat. Reduce heat and simmer 10 minutes. Pour fruit into jelly bag over a saucepan or in a cheese-cloth lined colander set in a large saucepan; allow to drain. Avoid squeezing bag. Measure 4 cups juice into a kettle; add sugar and stir well.