Above: Used Ball lids. The one on the left clearly shows the groove left by the canning jar. The one on the right was boiled for 20 minutes, which flattened that groove considerably. I picked up this tip boiling lids if you plan to re-use them from the blog A Traditional Life.
One of the many U.S. shortages that occurred during the COVID-19 pandemic was a shortage of lids for use in home canning. I’ve posted extensively on that here. Continue reading Post G22-011: Canning lids, from shortage to wide-mouth surcharge.