Jean should not be canning tomatoes at room temperature. Not only do the tomatoes need to be slightly cooked in order to be preserved, but the lids must be boiled slightly to soften the lining and the entire jar must be heated in a boiling water bath for 30 minutes or more in order to create a vacuum seal. Without the boiling water bath and vacuum seal, the tomatoes are virtually guaranteed to form mold spores or worse. If the rings were cool enough for Libby's uncalloused hands, they are far too cool to be used safely.