Abstract: A method and apparatus for testing the pressure venting characteristics of canning jar lids. A pressure chamber in the form of a mock jar finish has a canning jar lid fastened to it in the manner which the lid will be fastened under actual canning conditions. The chamber and the lid are then placed in a liquid bath which reproduces temperature conditions present during canning, and the chamber and the lid are allowed to stand in the bath until they come to the temperature of the bath. The chamber is then pressurized, and the pressure monitored until the canning jar lid is observed to vent gas; bubbles in the liquid in the bath indicating that venting is occurring. This pressure is then noted and serves as a measure of venting characteristics of the jar lid. Also disclosed is an apparatus for practicing the method.