Many people think sealing jelly jars with paraffin (baker's wax, canning wax) to be old fashioned. It is still, however, a viable canning method for short time periods. Paraffin sealed jellies should be used within a couple of months. For longer periods, before use of canned goods, the two part method of a metal ring and lid (in a hot canning bath) should be used for safety.
Prepare your jelly with the recipe of your choice. Pour the jelly into the sterilized glass jars, leaving ½ to 1 inch of space at the top, for the paraffin.
Use a double boiler to melt the paraffin wax. If you don't have one available, use a large pot and smaller pot inside. Fill the larger pot halfway with water, place the smaller pot with a chopped-up bar of paraffin wax inside, on top of the water in the larger pot. Bring the water to a boil, as the wax melts. This process can be started as the jelly making is nearly finished.
Place a candy thermometer in the wax, keeping the temperature below 375 degrees F. Paraffin can catch on fire if it becomes too hot. When the wax is completely melted it will have a clear, water-like consistency. At this time the jelly should have set (become slightly solid) and cooled, somewhat.
Spoon the melted wax onto the top of the jelly in the jars, nearly up to the jar top. Tilt the jars, a bit, to make sure the wax has adhered to the sides of the jars. Allow the wax-topped jars to set until the wax is opaque (white in color and not see through).
Place the jar lid over the top of the opaque paraffin and screw it on tight. As the wax and jelly cool further, the lid is pulled down sealing the jelly in, so it is safe for storage and later use.
Remove the lid and then the layer of paraffin wax when you are ready to use the jelly. The wax should be solid and come out easily. Throw the wax away. If you see any mold on the wax bottom or jelly, the canned food is not fit for human consumption and could cause illness. Through all of the jelly in that jar away. If the jelly is fine, replace the lid after the first use and store it in the refrigerator.