I havealways been told to pack the jars at about the same firmness as you do your pipe. My mentor told me that and it sure seems to haveworked for me. I do live in the high desert and it is dry. I have open a jar that was almost 10 years old and it was just fine. I do heat the jars a bit when I clean them and many times have heard the pop when they seal. I do pour hot water over the lids and then dry them by hand. Like I said, it sure seems to work for me.