What causes canning jars to break?
Rating: 100 There are several types of breaks that can occur during canning. Each break looks different and can be used to identify the problem. Thermal shock is characterized by a crack running around the base of the jar that may extend up the side of the jar slightly. This could be described as the bottom falling out of the jar. To prevent this from happening, avoid sudden temperature changes, such as putting a hot jar on a cool or wet surface or putting hot food or liquid in a room-temperature jar, or plunging raw packed jars into boiling water. Also use a rack in the canner. Avoid using metal knives or spatulas to remove air bubbles or steel wool pads to clean jars as this might weaken the jar and make it susceptible to thermal shock. Internal pressure breaks are characterized by a vertical crack that divides and forks into two fissures. This is usually on the side of the jar away from the name imprint. In order to prevent pressure breaks, be sure to use the correct amount of heads
