Wash your jars, lids, and canning tools using hot soapy water. Thoroughly rinse to eliminate any soap residue. Allow them to dry on a clean kitchen towel.

Set up the water bath canner and position the jar rack inside. Arrange the jars on the rack. Fill the canner with enough water to cover the jars.

Heat the canner over medium heat until it reaches a simmer at approximately 180˚F. Let the jars warm up in the canner for about 10 minutes, ensuring they remain warm until it's time to fill them.

Thoroughly rinse the blueberries under fresh running water. Remove any stems and mash the berries with a potato masher. Measure out 4 cups of mashed blueberries.

Add the sugar (or honey) and 2 teaspoons Pomona's pectin powder in a small bowl. Mix well to combine and set aside.

Make the calcium water mixture by combining 1/2 teaspoon of calcium powder (from the small packet found in the Pomona's pectin box) with 1/2 cup of water in a jar that has a secure lid. Shake the jar vigorously to ensure the ingredients are well mixed.

Combine the mashed blueberries, lemon juice, and 2 teaspoons of the calcium water in a large saucepan.

Place the saucepan over medium-high heat and bring the blueberry mixture to a boil. Stir frequently to prevent scorching.

Once boiling, slowly add the sugar and pectin mixture, stirring consistently until it dissolves completely.

Continue stirring until the jam reaches a full boil again, which should take around 1 to 2 minutes. Once it reaches a full boil, remove the saucepan from the heat.

Place a kitchen towel on the counter surface. Using the jar lifter, carefully remove a jar from the canner and tilt it to empty the water back into the canner. Then set the jar on the towel.

Use the canning ladle and funnel to fill the jar with the blueberry jam. Leave a 1/4-inch headspace at the top.

Run the bubble popper through the jar to release any trapped air bubbles. Then use a clean, damp towel and wipe the rim of the jar.

Center a lid on top of the jar, and screw on a band until it is fingertip tight. Then, using the jar lifter, return the filled jar to the canner. Repeat the process with the remaining jars.

Once all the filled jars are in the canner, adjust the water level so the jars are submerged and covered with two inches above the tops of the jars.

Cover the canner and set the heat to high. Allow the water to reach a vigorous boil, and then continue boiling for 10 minutes if you are at an altitude of less than 1,000 feet. Adjust the processing time according to your altitude if needed (Refer to Notes).

Once the processing time is complete, turn off the heat, and let the canner cool down and settle for approximately 5 minutes.

Prepare the counter by spreading a dry kitchen towel. Then remove the cover by tilting it away from you to avoid any potential steam burns.

Use the jar lifter to take the jars out of the canner and place them on the towel. Keep the jars upright and avoid tightening the bands or checking the seals at this stage. Allow the jars to sit undisturbed for 12 to 24 hours to cool.

After 12 to 24 hours, check if the jar lids have sealed properly by pressing on the center of each cover. The lids should not pop up; they should remain firmly sealed. If the top flexes up and down, it indicates an improper seal. In this case, pop the lid, refrigerate the jar, and use the jam within 2 weeks.

Remove the screw-on bands, wash the jars, and label them with the date and contents. Then store the jars in a cool, dark place. For the best flavor, use the jam within 12 to 18 months. Once opened, refrigerate the jam and consume it within 2 weeks. This recipe yields approximately 4 to 5 half-pint jars.