
Glass Container
Mason/Canning Jar
The mason jar (also called a canning jar) is a thick-walled glass container with external threads and a two-piece metal lid system: a flat stamped-steel disc with a sealing compound, and a separate threaded screw band that holds the disc against the jar rim. Patented by John Landis Mason in 1858, this design creates an airtight vacuum seal during the heat-canning process. The glass is heat-tempered to withstand both water-bath and pressure canning.
Mason jars come in two mouth sizes: regular (70mm) and wide-mouth (86mm), with standard sizes from 4 oz (half-cup) up to 32 oz (quart).
