WonderBag official website. This will give you a basic primer on the advantages of using this method. They are about $85 new on Amazon, plus shipping from Africa.
Thermal cooking has been around for centuries, but we are just rediscovering it. This is essentially crock pot cooking without the need for electricity. Get the food boiling and started for 20 minutes and then put in the thermal cooker to retain the heat and finish the cooking process. Perfect for a rocket stove application!
Wonder Box Bread
Katzkradul video on how to make a thermal cooker.
Step by step on making a wonder oven.
There are lots of YouTube videos out there. Of those I found, I thought these were pretty good. I do plan on
making one and I will incorporate Mylar into mine. Probably sit the pot on it as it is easily washed.
I ran a little Mylar thermal heat retention mini-experiment by boiling two cups of water in the microwave. I sat both on the oven top, but wrapped one in Mylar. In just one layer of Mylar it lost approximately 15 degrees every 10 minutes starting from 212 degrees and using a meat thermometer. The uncovered cup was lukewarm within 10 minutes – very normal from my experience with coffee and tea. The cup wrapped in Mylar was still 100 degrees after 1 hr.
Also, I’m inclined to put it in a box simply because I have critters that would see the whole bag thing as a potential toy – And of course, I would lose the top pillow!