Prepare fruit by removing stems from berries and crush. use food processor to crush strawberries into the finest liquid. You can strain juice through several pieces of cheesecloth of pantyhose to remove all the seeds.
Measure exact amount of prepared juice and pour into 6 - 8 quart saucepot. You can add up to ½ cup of water to get the exact measurement.
Stir pectin into juice in saucepot. Add butter to reduce foaming. Bring mixture to a full rolling boil (a boil that does't stop bubbling when stirred) on high heat, stirring constantly.
Stir in sugar. Return to full rolling boil, stirring constantly. Boil exactly 1 minute, stirring constantly. Remove from heat. Skim off any foam with metal spoon.
Laddle immediately into prepared jars, filling to within ¼ inch of tops. Wipe jar rims and threads. Cover with two-piece lids. Screw bands tightly. After jars cool, check seals by pressing middle of lid with finger. If lid springs back, lid is not sealed and refrigeration is needed. If sealed, store in cabinet until ready to eat.