More About Canning Jar Racks at Blain's Farm & Fleet
Inside a canner, a canning rack is designed to hold the jars slightly above the bottom of the pot so they don’t sit directly on the hottest surface. By creating this small gap, the rack allows hot water or steam to move freely around the jars, which promotes more even heating during processing and helps the jars stay upright and level.
Keeping jars off the canner’s base also reduces the chance of damage. The bottom of the pot can develop hot spots, and if a cool or warming jar rests directly on that surface, the sudden temperature difference can lead to thermal shock—stress on the glass that can cause cracking or breakage. A canning rack also helps keep the jars separated and stable, so they are less likely to tip or bump into each other while boiling. This lowers the risk of jar failure during canning.
Many racks have handles that let you lift the entire rack out at once, reducing the amount of time your hands have to be near steam and hot water. It also makes it easier to remove jars from the canner smoothly without scraping the bottom of the pot.