Thoroughly wash the canning tools, jars, and lids with hot soapy water. Rinse well and allow them to air dry on a clean kitchen towel.

Place the jar rack in the water bath canner, arrange the jars on the rack, and add enough water to cover the jars.

Bring the canner to a simmer (180˚F) over medium heat, warm the jars for at least 10 minutes, and then keep them warm until you are ready to fill them.

Rinse the raspberries under cool running water, removing any stems. Mash the berries and measure 4 cups of mashed raspberries. Set aside.

In a small bowl, combine the sugar (or honey) and 2 teaspoons of Pomona's pectin powder. Mix well and set aside.

Prepare your calcium water by combining 1/2 teaspoon calcium powder (from the small packet in the Pomona's pectin box) with 1/2 cup water in a jar with a lid. Shake well to mix.

In a medium pot, combine the mashed raspberries, 2 teaspoons of the prepared calcium water, and lemon juice if using.

Place the pot over medium-high heat and bring the mixture to a boil. Once it boils, add the sugar/pectin mixture and stir well to dissolve.

Continue stirring until the jam returns to a full boil, about 1 to 2 minutes. Then, remove the pot from the heat and fill your jars.

Spread a kitchen towel on the counter. Using a jar lifter, carefully remove a jar from the canner, allowing the water to drain back into the canner. Place the jar on the towel.

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

Run a bubble popper through the jar to release any air bubbles, then wipe the rim with a clean, damp towel to remove any sticky residue.

Add the lid and screw the band on until it is fingertip tight.

Place the filled jar back into the canner, and repeat this process with each jar.

Once all the filled jars are in the canner, adjust the water level so it is at least 2 inches above the jar tops.

Cover the canner and bring it to a vigorous boil over high heat. Once it boils, set a timer and process for 10 minutes for altitudes below 1,000 feet. Adjust processing time according to your altitude if needed (See notes).

After the processing time is complete, turn off the heat and allow the canner to cool down for about 5 minutes.

Spread a dry kitchen towel on your work surface. Carefully remove the cover by tilting it away to avoid steam burns.

Use the jar lifter to remove the jars from the canner and place them on the towel. Keep the jars upright, and don't tighten bands or check the seals yet. Let sit undisturbed for 12 to 24 hours to cool.

Check the jar lids after 12 to 24 hours to ensure they have sealed properly. Press the center of each lid; it should not pop up or flex.

Refrigerate any jars that didn't seal properly and consume their contents within 2 weeks.

Remove the screw-on bands, wash the jars, and label them with the date and contents. Store the sealed jars in a cool, dark place.

For optimal flavor, use the jam within 12 to 18 months. Once opened, refrigerate and consume within 2 weeks. This recipe will make about 4 to 5 half-pint jars of jam.