Fill a hot water canner about 2/3 rds full with water and bring it to a boil.

Using a sieve, crush the blackberries to remove the majority of the seeds. Measure 4 cups of prepared fruit into 6- or 8-qt. sauce pot. Add pectin and stir.

Combine the blackberries, pectin, and lime juice and bring to a full rolling boil, reduce heat, and stir in sugar. Return to a full rolling boil and boil for 4 minutes, stirring constantly to avoid boiling over. Remove from heat and skim off any foam with a metal spoon.

Test to see if it has “set” by spooning a bit onto a cold plate.  If it has formed a bit of a skin and started to give a bit like goopy Jell-O, you’re good to go, if not, cook for a bit longer.

When the blackberry lime jam is ready, ladle immediately into prepared jars, filling to within 1/4 inch of tops. Remove any air bubbles. 

Wipe the jar rims and threads clean if needed. If using traditional canning jars, cover with 2-piece lids. Screw bands on.

If using Weck jars, carefully place the Weck rubber gasket on the lid of the jars. Place the lid on the jar and secure the lid with 2 evenly spaced Weck clamps. 

Place jars on an elevated rack in a hot water bath canner. Lower rack into canner. {Water must cover jars by 2 inches. Add boiling water, if necessary.}

Cover; bring water to a boil. Process 10 min. Remove jars and place upright on a towel to cool completely. Cool jars for 12-24 hours. 

After the jars have cooled, check the seals by pressing the middle of the lids with your finger {traditional canning jars}. If the lids spring back, the lid is not sealed and refrigeration is necessary. 

For Weck jars, check to make sure your seal is pointing downwards. Remove rings or clamps and store jars in a cool dark place. 

Yields about {10} 1/2 pints or about {12} #902 Weck jars