This is something I found on Pinterest and I was a little doubtful. I tested the method on dried mint. It worked wonderfully. The emphasis is on dry. You can use this method on dry, uncooked pasta. You can use it for dried herbs. It works for storing dry cereal. It works on most nuts if the nuts don't have a high oil/fat content (no walnuts!) and it will work on dried fruit, but not jellies, jams, or raw fruit. Dry, dry, dry! This is the method to use when you stocked up on 8 boxes of oatmeal but you're concerned about bugs getting in the boxes before you use it all.
Place filled jars without lids on a cookie sheet and bake at 200 for 1 hour. I placed the jars in the oven and THEN turned on the heat because I didn't want anything to crack or shatter. Please buy new canning jars. Please don't reuse old jars that were gathering dust in the shed. You want a clean jar that can take heat. Left over food bits from old jars will cause spoilage.
After one hour, wipe jar rims with a damp towel, then screw lids on tight. Jars are hot! Protect your hands. I used a damp dish rag and wore oven mitts.
Jar is sealed if the button stays down when pushed in. When I tried this, the lid gave a loud 'pop' when I pressed it. I left the jar sitting on the counter over night to cool. In the morning, I wrote the contents and date on the lid, then put the jar in my pantry. The mint looks exactly the same as when I canned it. I realize dried mint will keep just fine on its own, but I just wanted to experiment without worry of food going bad. Anyway, there's something really cool about jars of herbs lined on the shelves, and if it still has its aroma three years later, that's even better.
Added note- how I label jars for magickal purposes:
I don't like to write the uses of potions and herbs where anyone can see it because that leads to ideas. "You have a love spell? Will it work on my crush?" Next thing you know, jars are missing. I like planning ahead and stocking up. Astrological correspondences are NEVER aligned in an emergency. I look ahead, find times conductive to love, health, prosperity, etc. and that's when I make my potions and powders rather than scrambling about when I need a spell. After I make the spell and seal the jar, I tie a ribbon or cord around the jar neck. Black is banishing, white is cleansing or healing, red is love, green is money. Sometimes I use charms- a moon for the Goddess or a paw for animal magick. You could also use colored bottles or you could put a dab of nail polish on the cap. Then you'll be the only one who knows what's in the blue bottle with the silver ribbon.