Equipment and Methods Not Recommended for Home Canning
Processing freshly filled jars in conventional ovens, microwave ovens, and dishwashers is not recommended because these practices do not prevent all risks of spoilage. The following list details other methods of canning and preserving to avoid.
Steam canners. Processing times for use with current models have not been adequately researched. Steam canners may not heat foods in the same manner as boiling water canners, so this could require changing processing times. Without certainty, food spoilage may result.
Pressure processes that are in excess of 15 PSI, especially when using new pressure canning equipment. Most manufacturers also do not recommend operating their pressure canners above 15 PSI.
Canning powders. These are not preservatives. You still need to properly process your canned goods.
Jars with wire bails and glass caps. While these make attractive antiques or storage containers for dry food ingredients, they’re not recommended for use in canning.
Using old lids (even unused ones). The longer a lid sits, the more likely it is that it won’t seal right. Don’t purchase more lids than you anticipate using in a year.
Finally, one-piece zinc porcelain-lined caps are no longer recommended.
Both glass and zinc caps use flat rubber rings for sealing jars, but too often they fail to seal properly.