As soon as GrammMary emailed me about the WonderBag and I researched it, I wanted one! That way I can use the solar oven if we have sun and a thermal cooker for the Deadwood rocket stove. One pot meals that I can walk away from and do other things. But I didn’t want to have to go through that much work with sewing patterns, etc.
So how did I go about making my DIY WonderBag? First I knew I wanted a box to keep the critters out of the food and for clean and easy storage. I had picked up this cute little plastic chest after Halloween for $2.50 at Walmart, but didn’t have a use for it. I had already run the Mylar around a cup of boiling water experiment and was pretty sure this would work, but I still needed padding.
As I was wondering around the Salvation Army used store I ran into baby bumpers for $2 – right within my budget!
- Chest, Mylar, baby bumper.
So I had already bought a tub of border adhesive (a large quantity of white glue basically) to play with Mylar on my shades, so I used a disposable brush and coated the inside of the chest and lid with border adhesive and adhered the Mylar to that – went very well and made me look forward to the shade project.
- Mylar lined chest.
The baby bumper actually worked out slick as it was about the right height going around and about right under and on top. As you can see, I had leftover so I made up extra covers as heat rises. No sew, just tuck.
- Baby bumper lining.
On the same trip I had picked up some Graniteware for my solar cooker. The Graniteware all fits as does my cast iron Dutch oven. So far so good – considering I never measure anything if I can get away with it. I lined it with another sheet of Mylar to be gathered at the top and secured with a twist tie.
- Granitewear and extra baby bumper.
I decided on the Dutch oven for this experiment, since I hadn’t washed the Graniteware yet. And knowing that Mylar will melt at 212 degrees I put a pad on the bottom and “diapered” my pot with a leftover piece of blue jean fabric – I do like to be color coordinated! LOL :-D
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- More Mylar and “diaper” for the pot.
So then I decided to do a “waste not want not” meal – Every leftover in the fridge along with frozen pork chops that I nuked enough to get them apart. Boiled for a little less than 20 minutes – seemed plenty hot to me. Diapered the pot, set it in the thermal cooker (I put a meat thermometer in there just to see.), wrapped the Mylar around it, twist tied that, put the extra bumpers over it, and put the lid on the chest.
- Thermal cooker closed and animal resistant.
Bob woke up about then and commented on the delicious smell and asked what I was cooking. “Pork chops,” I said so innocently. I have learned not to tell Bob what I am cooking or he won’t necessarily eat it – goes back to when I butchered that filly that broke her leg and served him “Blaze”. Told him about Blaze after he enjoyed his meal – ya, didn’t go over too well…
Four and a half hours later, I have…
A WONDERFULLY AWESOME TOTAL SUCCESS!!!
Wow, the Dutch oven was still too hot to touch with just my hands and the meat thermometer read 150 degrees after 4.5 hours with no heat!!! The meat was super tender and moist and the accompanying “stew” just needs some more doctoring with a few herbs.
Bob watched me take it out of the chest and asked me what heat source I was using?! “Nothing,” I said rather confused as he could see it was sitting in the middle of the living room floor – no cords, no fire, nothing, just a black box.
Bottom Line
- A plastic box, Mylar, a blanket or anything for padding (Probably doesn’t actually need the extra Mylar)
- Probably cooks in a lot less time if I had bothered to check it.
- No electric used
- Faster and easier than a traditional electric crock pot.
- After thoughts… I don’t think you need to boil something 20 minutes in a Dutch oven. Get it hot and let it do its job.
- How can this be used? Think about a camp stove or rocket stove – camping, on the road cooking, anything you can do in a crock pot or Dutch oven you can do with this thermal cooker/oven!
Now I just need to figure out how to make an oven for my rocket stove as I like my bread with a brown crust… Metal breadbox? Broken toaster oven? We’ll just have to see what I run across.
All this in a blizzard with thunder snow and lightening – will my roof cave in?
I share the comments of the wife….
“They had the same thing on the BBC ‘War Time Farm’ (WWII) episode. Get a box and line with hay. Put you stew on the stove until it reaches a boil. Slap on the lid and put in the hay filled box. Cover the box with a ‘pillow’ full of hay. Go about your business :)
The secret is to have the food boiling.
Personally, I don’t think she’ll have as much success with the granite ware. That is a thinner material and less heat mass.
Q=cm∆T
Q is the heat added (in this case getting the material in the pot to boiling
C is the specific heat
∆ is change
T is temperature
M is mass
So the greater the mass of the initial product (pot + food) the longer it will take for the temperature to change (lower).
I think it would definitely work better with cast iron and thereby preserve the ‘thermal’ part of the thermal cooker. The mylar only serves to reflect the heat back into the area where the pot is. I’d be more inclined to use something like thick batting. The air pockets in the batting would give you the insulation (thereby eliminating the baby bumpers).
And yes, I did know the heat equation above. Just more useless knowledge in there.”
Thanks Phil! Yesterday’s post was all about the batting, etc. for thermal cooking. And yes, the secret is getting it good and hot and then keeping the heat in without electric.
The Mylar, IMHO, is the key to a fast, lightweight, easy to use cooker. And I think the seal of the plastic may have something to do with it. And yes, the cast iron has great mass. But they aren’t using cast iron in many under developed countries where this is popular. And the baking video in tin cans leads me to believe that granitewear will work just fine.
But hey, send me YOUR experiments! We will all learn…
Bev :-D
Sounds like Bev’s on a roll :-) We still haven’t put our “system” together, but we’re confident it will work…we’ve seen tons of video’s using various methods, and they all work. Like you said, bringing the food to it’s highest heat level & then isolating that heat wins the biggest part of the battle. Once cast iron gets hot it stays hot longer than most cooking equipment. I have a very nice stainless steel pressure cooker (not canner) that’s teflon lined. I’ll be using that inside my wonder box. I’ll need MrWE2 to cover the exhaust valve (no gauge or regulator) to keep the heat from escaping & getting things steamy wet. But I love using that cooker and want to use it if at all possible because with the gasket seal, it should really hold the heat inside. “When” I put it together I’ll email the stuff to you, but right now we’re really concentrating on the Roost on Fri, Sat & Sun, so MrWE2 isn’t available unless it’s in the evenings…and after he’s worked, and I try not to engage him in anything. But I can almost “feel” your excitement! As for your hubby…in a crisis situation, perhaps you should let him go without a meal or two :-) “-) for him to understand the important of nice hot food.
ooops…”importance” of nice hot food. Wish we had a way to edit our post when we goof!
This type of cooker would also be great for leaching the goodness out bones when making bone broth. It was recommended to me that one should keep the bones boiling for 12 hours, but that is terribly expensive on fuel unless one has a range that is providing general heating for the house. Bone broth is one of the great basic health foods there is. So a cheap way to do it is wonderful.
I do think one of the keys to making this type of cooking appliance is to make it so its easy to wash as I don’t know about you but I tend to spill things when I’m moving heavy pots around.
I hear you about slopping Harriet as I do it all the time. Mylar wipes clean with a wash cloth – another thing I like about Mylar!
The “diaper” is any washable cloth.
And of course the baby bumper is washable, especially if I finish the ends.
So, it is ALL washable!
“Cleanliness is next to Godliness…” I think that’s how it goes… May not have spelled it right but you get the gist.
I’ve played around with thermal cooking a little and it has worked “OK” I use a medium sized coleman cooler and put old towels on the bottom or really just stuff them all around. It hasn’t kept as hot as I would like and I used my standard steel pot but next time i will use my dutch oven. Don’t know why I didn’t think of that!
For me the Mylar is the secret to the heat retention.