Select tart apples. Wash and quarter the apples (skin on, with seeds- these parts contain high amounts of natural pectin).
Place the apples into your preserving pot and cover with just enough water to float the apples. Too much water will dilute the pectin.
Cover and bring to a boil over medium-high heat. Once a boil is reached, reduce the heat and cook at a low simmer for 2-2 ½ hours. An easy mistake you must avoid is stirring your apples! This eliminates sediment fallout, which’ll give your final product an undesirable haze and make it hard to strain.
When the apples have cooked down considerably, are incredibly mushy and resemble chunky applesauce.
Line a colander with several layers of cheesecloth, coffee liners, or a tea towel. Stack the colander over a large pot, strain the liquid through it. Let things drip for several hours (and up to overnight) at room temperature. You’ll again have to resist the temptation to press the pulp so that you don’t get cloudy pectin.
Return the pectin to the stove and bring to a simmer over moderate until it reduces by half of its original volume. it’s nearly ready! But, before you jar it up, test your pectin’s ability to gel.
Remove 1 teaspoon of pectin and allow it to cool. Mix it with 1 tablespoon of rubbing alcohol. Your fruit pectin is high if a gelatinous glob forms that can be picked up with a fork. If the fruit pectin is average, you’ll get a few coagulated chunks. If that’s the case, return the liquid to a boil and continue to reduce. Discard the test batch.
Pour hot pectin immediately into sterilized half-pint mason jars, leaving ¼ headspace. Wipe the rim of the jars with a dampened cleaned towel to remove any residue that may prevent your jars having an airtight seal.
Apply new canning lids and firmly (not not forcefully) securely with a screw band to hold the flat lid in place. Process in a boiling water bath for 10 minutes.