Hobbies And Interests
History
Hermetic sealing, the process that preserves canned food and makes it sterile, originated in France in 1809 as a means of transporting food to troops. This method of preservation did not become popular until the late nineteenth century, when appropriate containers were developed. Food was stored in crude glass or pottery containers and sealed with cork. Later, more secure metal containers were invented, but these could not be reused and reacted poorly with high acid foods.
Features
The first glass canning jars were sealed with wax. The now famous Mason jars were the first to use a threaded ring and lid with a rubber seal. Patented in 1858, this jar revolutionized canning. The containers were reusable, affordable, and the process of sealing and unsealing became much easier and safer.
Identification
Canning jars can be identified by their closure and shape. Early canning jars may have been closed with a metal clamp or a vacuum-sealed stopper. Jars intended to store solid food items typically have a wider mouth for ease in both packing and removing the preserved product. Canning jars used to store liquid products such as oils may have narrower necks and openings. Manufacturing imprints and the color of the glass can also be used to identify canning jars.