I created a long-term storage room for dried foods by enclosing part of the back porch. Unfortunately, we soon needed the space so I moved jars of anything that would not freeze and break out to the root cellar, which remains above freezing usually, but also a little dampish because it is set into the hillside. By the end of last winter, the lids to the mason jars I use for storage were showing spots of rust.
I took off the lids and rings of about 2 dozen jars and spray-painted them (just the outside of the lids, but both sides of the rings). It took forever to get a good coating inside and outside of the screw channels on the rings, and I used up an entire can of spray paint. That stopped the project because I still had well over a hundred jars to go... jars of beans, pasta, grains, dry fruit... you get the picture.
Ball makes a plastic replacement lid for both wide-mouth and regular canning jars (NOT to use in canning, just opened cans in the fridge), but they would be expensive because I need so many. So the jars have been sitting on the root cellar shelves, rusting slowly into total decay. I figure about 3 more years, and the rust will have eaten a hole all the way through the lids.
However, last week I came across a post somewhere about waxing cans and boxes for long-tern storage, to prevent rust in metal cans, and insect invasion in cardboard boxes. They just melted beeswax or paraffin in a large double-boiler (actually a stockpot large enough to hold a cereal box, inside a larger pan of water) and dipped the containers, first the top half, and when cooled, dipped the bottom half. I don't see any reason this wouldn't work for my mason jars.
I would only have to dip about 2" of the jars to cover the lids completely, thus not needing nearly as much wax as if I had commercial metal food cans needing to be covered entirely. Paraffin, a petroleum product, is less expensive than beeswax or a vegetable candle wax and since it won't contact any food I'm okay with trying it.
Next month I will wax some, and see how they fare over this next winter. I have the idea it will work just fine!