1.1 This test method covers the determination of the relative resistance of commercial glass containers (bottles and jars) to thermal shock and is intended to apply to all types of glass containers tha This test method covers the determination of the relative thermal shock resistance of commercial bottles and jars and is intended to apply to all types of glass containers that are required to withstand sudden changes in temperature in service. The test apparatus consists essentially of a basket for holding the glassware upright, a hot water tank, a cold water tank, and a timed means for immersing and transferring the basket from the hot to the cold bath. Indicating controllers or dial thermometers should be used to maintain the temperatures of the baths. Test procedures included in this specification include pass tests, progressive tests to a predetermined percent of breakage, total progressive tests, and high-level tests.