By far the most important step in safe home canning is to follow an up-to-date, research tested recipe. Research-tested recipes recommend metal 2-piece lids for home canning. Two-piece lids are sold to fit regular and wide-mouth glass canning jars and are made up of a flat metal lid and a metal screw band. The lid contains a sealing compound that, when properly used, softens during the canning process and forms an airtight seal as the container cools.
Traditional metal lids are designed to be used only once. Reusing traditional lids will result in seal failure; the indentation left in the sealing compound on the first use will prevent an airtight seal from forming the second time. Unused lids should be stored in a cool, dry location and may be good for up to 5 years from the date of manufacture. Over time the sealing compound will degrade and the lid may fail to seal.
Best practices for ensuring a safe seal on canning jars. These tips will help ensure that your jars seal and stay sealed.
- Follow the manufacturer’s directions for preparing lids. Traditionally, lids were simmered or boiled prior to applying to jars, but this is generally not the case now. Check the directions.
- Always wash and rinse lids and bands prior to use.
- Leave the proper headspace.
- Clean the jar rim (sealing surface) prior to applying the lid. Food or debris trapped on the jar rim can cause seal failures.
- Place the metal screw band over the flat lid and apply finger-tip tight. Screw bands that are applied too loose, or too tight, can cause jars not to seal properly.
After processing, remove jars from the canner and allow to cool, undisturbed. Do not re-tighten screw bands. Once jars are completely cool, check for seal. It’s a good idea to remove screw bands for storage. When removed, washed, dried, and stored in a dry area, screw bands may be used many times. If left on stored jars, they become difficult to remove, often rust, and may not work properly again.
Are reusable lids safe for home-based canning? Recent research suggests that reusable lids such as the Tattler-brand* will safely seal jars when used for home-based canning. This type of reusable lid is used with a thin rubber gasket. A metal screw band is also needed during canning!
What do I need to know if I used a reusable canning jar lid? Follow these tips:
- Follow the manufacturer’s instructions for use.
- Follow ‘best practices’ for using a metal lid and screw band, applying the lid, gasket and metal screw-band when sealing the jar.
Note, manufacturer’s instruction may instruct the user to tighten the metal band immediately upon removal from the canner. If instructed, you should do so. Tightening the screw band ensures that the gasket forms a seal. The metal screw band is removed once the container is cooled and a seal has formed. *Reference to a brand name is not to be seen as an endorsement for this product.
To help ensure a jar seal, limit reusable lids to 10-trips. Use a permanent marker to tally each canning ‘trip’ for a reusable lid and gasket. Once you’ve reached ’10 trips’, it’s time to replace the lids (and gaskets). Always replace reusable lids and gaskets if you notice cuts or tears in the material.
And one final note. Many consumers have noticed inferior quality of canning supplies ordered over the last year (2020). To ensure quality, consider ordering directly from the manufacturer or their representative and not from a third party vendor.
A handout with this information is available.