What’s new in the world of canning? For some people, canning jar lids are the hot topic of the day. Recipes supported by UW-Extension recommend standard 2-piece metal lids for home canning. Last year Jarden Brands (manufacturer of Ball and Kerr-branded products) began instructing consumers that their lids no longer had to be pre-warmed prior to placement on the jar. Since treatment of lids has long been important in jar sealing, it is a good time to review this topic.
The material that coats the metal on many home canning lids has been reformulated in order to remove the chemical bis-phenol A or BPA. While there have been no scientifically documented health issues linked to BPA in home canning lids, companies such as Jarden took the precautionary step of reformulating the materials in the lids.
Because of the new lid formulation, Ball/Kerr no longer require pre-heating of lids. New boxes of lids from Ball/Kerr indicate that the lids should just be washed and set aside for applying to jars. Most of the lids manufactured in the United States are made by Ball. If you buy lids in bulk or are otherwise unsure how to pre-treat lids for canning, it can be important to note that some consumers have noticed better sealing (fewer seal failures) if the new lids are lightly pre-warmed prior to use. Jarden indicates that lids may be pre-warmed without threatening seal failure; boiling will thin the sealing compound and cause lids not to seal.
Here are some tips for success:
- Use 2-piece metal lids for home canning. The design of home canning lids allows air to escape during canning, helping to form a vacuum seal and ensuring a shelf-stable product.
- Use lids only once. The newer lids have a thinner application of sealing compound. They should not be reused.
- Lightly pre-warm lids in simmering water, 180°F. Do not boil! Many years ago, Kerr lids were boiled prior to use to soften the sealing surface. This is no longer necessary and will actually harm the sealant and cause seal failure. I have found that a small crock pot is a great way to heat lids without getting them too hot.
- Store lids in a cool, dry location. The sealing compound can crack and become brittle if the lids are stored in a hot, dry location. Purchase new lids every year, if possible. Old lids may cause seal failure. If you prepare more lids than you need, be sure they are dry before storing then until your next canning event.
- Take care to avoid scratching the lid surface. Lids are actually delicate. The sealing surface and the compound covering the metal lid can be easily scratched. Don’t use tongs to retrieve lids from warm water. Instead, opt for a ‘lid wand’ or, my favorite, a telescoping plumber’s magnet (pictured right) to quickly and efficiently retrieve lids from water.
- Tighten lid bands ‘finger tip tight.’ The purpose of the band is to hold the light lightly in place so that it drops down onto the jar rim once air is removed from the jar. If bands are tightened too tight, you risk jar breakage or seal failure.
The new lids function equally well for boiling water canning and pressure canning. The National Center for Home Food Preservation still does not recommend reusable canning lids for home use. Safe preserving! Barb