The disposable ones work by oxidizing iron, a.k.a. rusting. Oxygen will make its way through the plastic, but how you store them makes a big difference. I buy them in bulk and then put them in a sealed ammo can. Just taking out a few that I need from time to time. I pull some out that were over five years old and still fine. I’ve also had some go bad in my hiking pack within about 2 to 3 months. Mostly because the plastic develops small punctures. For the really big ones, you can also stop the reaction by sealing them in a plastic bag with all the air removed. I’ve done that one hunting and I want heat, but then shoot some thing early on. You can do the same with the small ones, it’s just far less effective.
That Zippo is real new school. I have two Jon-E warmers. The small one was patented in 1960 and the big one in 1970. Found the following history on the Jon-E.
Is that a fire in your pants or are you just happy to see me?Burned up a pair of pants with one of them over filled with lighter fluid back in the 60's - then they came out with that charcoal looking stick in the 70's that you would light one end and seal it in a red case. now I use a rechargeable one. Good for 6 hour and plug it back in to charge.
My grandfather always had these for ice fishing, along with the lantern in the sled.That Zippo is real new school. I have two Jon-E warmers. The small one was patented in 1960 and the big one in 1970. Found the following history on the Jon-E.
Smith was awarded a patent for his invention on December 25, 1951. The design of the Jon-E can be seen below. An article about the handwarmer in the Minneapolis Tribune in 1953 remarked that it looked like an oversized cigarette lighter. The chrome-plated device comes in two parts with an internal burner. It also comes with a red flannel carrying case, and a set of instructions.The Jon-e was manufactured at Aladdin Laboratories, Inc. of Minneapolis, where Smith was president. Aladdin was founded in 1930 and originally created cosmetic products until Smith developed the Jon-e. At the height of production in the fifties and sixties, the factory produced 10,000 warmers a day. In the following decade, Aladdin went out of business. Although, vintage Jon-e handwarmers can still be purchased online as the product was durable enough that it developed a reputation for longevity and reliability. The Jon-e was and is mainly used by hunters and fisherman, but Smith himself said, “The handwarmer market includes just about everyone who would rather be warm than cold.” It’s safe to say that includes all of us.
I used these when I was a dock supervisor at a truck line in Coldwater, Michigan in the early 70's. They still work.
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