Grape Jam - cooking recipe

Ingredients

3 1/2 lbs concord grapes
1/2 cup water
7 1/2 cups sugar
1/2 teaspoon butter
1 pouch Certo (pectin)

Preparation

Remove the skins from the pulp and set them aside.
Place grape pulp in stainless jelly pot with water.
Bring to boil and simmer 5 minutes.
Strain to remove the seeds.
Chop the skins and add to the cooked pulp.
Measure out 5 cups of the grape pulp mixture and return the pulp to jelly pot.
Add sugar and butter.
Heat on medium heat until sugar is melted, then adjust to high heat.
Heat and stir to full rolling boil that will not stop.
Add 1 pouch Certo and return to full rolling boil at high heat.
Boil exactly one minute stirring constantly.
Fill jars to 1/8 inch from the top.
Seal with lids.
Invert jars for 5 minutes.