Let jars cool on a cutting board or towel with 2 inches of space between each jar for 12 to 24 hours.
To check the seals, press down on the center of the lid. If the center of the lid doesn’t pop up, it’s sealed. To double-check the seal, remove the band and very gently try to remove the lid. If you can’t remove the lid, you have a good seal. The jar isn’t sealed if the lid pops up when you press down on the center of the lid or if you can remove the lid easily. Refrigerate any jars that didn’t seal for up to 3 weeks or freeze for up to 1 year.
SOURCES: Ball Blue Book of Preserving and The Complete Idiot’s Guide to Jams, Jellies and Preserves by Yvonne Tremblay.