As I was reading a recent SurvivalBlog post on the many uses of canning jars, I remembered that in my childhood days the ladies doing the canning would sometimes use melted paraffin poured over the top of the food instead of using metal lids.
(They also used metal lids.) So maybe the wax only on the sweet stuff like jellies, etc.? Maybe only on smaller size, smaller mouthed, recycled, jars?
As I remember it they would keep the paraffin, wash it, and reuse it the next year. Has anybody used this style of sealing lately? – K.S.
HJL’s Comment: The paraffin method was typically used on high acid foods like jellies and jams. I too remember seeing this. The paraffin came in contact with the food and kept a skin from forming on the surface. However, I also remember a significant number of failures.
JWR’s Comment: I strongly recommend following the proven safe canning procedures found in the Ball Complete Book of Home Preserving.  (That is an expanded and updated edition of the classic Ball Blue Book.)