Make sure all equipment is clean and in good condition, including the jars, lids (jar seals), and utensils. Wash everything in hot, soapy water, rinse well, and then place them in boiling water for 10 minutes to sterilize.
Use fresh, high-quality ingredients and follow a tested recipe from a reliable source. Be sure to follow the recipe’s instructions for preparing the food and packing it into the jars.
For proper use of jars it is recommended that you leave the recommended ample margin space, or headspace (the amount of space between the top of the food and the top of the jar) to allow for expansion during processing.
Process the jars in boiling water for the recommended amount of time, based on the recipe and altitude. Make sure the water remains at a rolling boil throughout the entire processing time.
Use jar lifters to remove the jars from the hot water and place them on a towel or cooling rack to cool. Do not tilt or move the jars until they are completely cool and the seal has formed.
After the jars have cooled, check the seals by pressing down on the center of the lid and remove the ring. If it does not move or make a popping sound, the seal is good. If the lid pops up and down, the jar did not seal properly and the food should be refrigerated or reprocessed.