Prepare supplies: Wash jars, lids, and rings in hot soapy water. Put jars in the water bath canner, and cover completely with water. Bring water to a simmer (don't need to boil). In a small saucepan, add lids and bring to a simmer. You don't need to add the rings. It is important to keep jars and lids hot or your jelly might not seal.
Prepare fruit: In a large saucepan, crush grapes with a potato masher. Add water; stir. Bring to boil; simmer on medium-low heat for 10 minutes. Strain juice through a fine sieve or strainer to remove debris. Juice should equal 4 cups. Add up to 1/2 cup of water, if needed, to make 4 cups.
Cook the jelly: Add juice, sugar, and butter to large saucepan; mix well. Bring mixture to a full rolling boil (a boil that doesn't stop bubbling when stirred) on high heat, stirring constantly. Boil exactly 1 minute, stirring constantly. Stir in liquid pectin. Return to a full rolling boil; boil exactly 1 minute, stirring constantly. Remove from heat. If not using a jelly bag, pour mixture through a strainer lined with 3 layers of cheesecloth. Tie cheesecloth closed; and let drip into bowl until dripping stops. Press gently with fingers or back of spoon. Insert funnel in top of jars and immediately ladle hot jelly mixture into prepared jars. Fill jars within ¼ or an eighth of top. Remove air bubbles using bubble remover and head space tool. Wipe jar lids and threads. Remove lid from pot using jar lifter. Center lid on jar, add ring, and screw tightly.
To process jelly: Place all jars in canner using jar lifter. Add enough water to cover by at least 1-2 inches and increase heat to high. Add additional boiling water if necessary. Once the water reaches a full boil, cover and boil for 5 minutes. Turn off heat and remove lid. Remove jars from canner; sit upright on towel. Cool completely before storing. After jars cool, check seals by pressing middle lids with finger. If lid springs back, lids are not sealed and jars will need to be refrigerated immediately.
Add label to each jar and mark with contents and date. Store in a cool dry place for up to one year.