2 teaspoons calcium water (included with Pomona’s Pectin)
Stem and crush or chop strawberries. Measure 2 cups into 6- or 8- quart sauce pot. Finely chop rhubarb; do not peel. Measure 2 1/2 cups into the sauce pot with the berries. Add calcium water to fruit mix.
Prepare jars. Keep lids warm until ready to fill jars.
Measure sugar into separate bowl. Stir pectin into sugar.
Bring fruit mixture to full rolling boil on high heat, stirring constantly. Quickly stir in sugar/pectin mix. Return to full rolling roil and boil exactly one minute, stirring constantly. Remove from heat; skim off any foam with a metal spoon, if desired.
Ladle into prepared jars, filling to within 1/4 inch of top. Wipe jar rims and threads. Cover with lids and screw bands. Tighten rings until snug.
Process for 10 minutes in a water bath canner. Turn off heat, let sit five minutes. Remove from canner and place on kitchen towel on counter top. After jars are cool, check seals.