Homemade jelly often calls for a jelly bag, which allows you to extract juice from boiled fruit. The juice is boiled with sugar and sometimes fruit pectin to transform it into jelly. If you don't have a jelly bag in your kitchen arsenal, you can make one with a few basic materials. You can even make a homemade jelly bag that's reusable and similar to the ones you would purchase in stores.
Quick, Disposable Version
Cheesecloth functions as a one-time-use jelly bag that doesn't require any other materials. Layer several sheets of damp cheesecloth in the bowl you plan to use to catch the juice. Spoon the fruit into the bowl on top of the cheesecloth, leaving a few inches of fabric on all sides. Gather the edges of the cheesecloth and tie them carefully to close the bag. Tie a thin strip of cheesecloth around the knot at the top, then tie it into a loop so you can hang the bag to allow the fruit to drain. For example, hang the bag from a cabinet handle and set the bowl underneath it. Throw the cheesecloth away when the fruit has finished draining.
Reusable Jelly Bag
Sew a jelly bag out of flour sack cloth that you can wash and reuse. Start with a long rectangle of fabric, then fold it in half so that it is half as long. Sew the two long sides closed by hand or with a machine, leaving an opening at the top of the bag. Make four small, vertical slits near the top of the bag opening on both sides and thread a long piece of yarn through them to create a drawstring. This will allow you to close the bag and hang it as it drains. After removing drained fruit from the bag, hand wash it thoroughly and allow it to dry before storing it for later use.
A fine mesh strainer or a flour sifter can stand in for a jelly bag. Balance either above a bowl for the juice to drain into. Or place a large-holed strainer into the leg of a clean -- preferably new -- pair of pantyhose and balance it above the bowl. You may also use just the leg from a pair of clean pantyhose hung above a bowl if you don't have a strainer on hand.
If the juice draining from the jelly bag is cloudy, too much of the fruit pulp has escaped with it. This may occur if the holes of the jelly bag are too large or after too much squeezing. Either way, re-strain the cloudy juice to remove more of the pulp before you use it. If you didn't get enough juice for the recipe and you just need a bit more, leave the pulp in the jelly bag and drizzle some water over it. The water will collect the juices as it drains into the bowl.