DIY BAG-STYLE HEAT RETENTION OVEN FROM UPCYCLED MATERIALS

Heat retention cooking has been around for a while, but is enjoying greater attention as people seek to be more economical and “green.” The concept involves bringing food to a boil for a specific amount of time and then moving the pot directly into a container filled with heat-retaining material, (like sawdust, hay, wool, or polystyrene), covering it, and letting the food sit for several hours. There are probably numerous ways to achieve this. Two that kept coming up in my Internet searches were a box design called the “wonder box,” and a (somewhat pricey) drawstring bag design called the “Wonderbag” that is being sold (http://nb-wonderbag.com/content/what-wonderbag). Both designs used cotton fabric and polystyrene balls, like those used in bean bag chairs. However, since I had read that shredded polystyrene packing peanuts could be used for the filler and I had an old partly cotton sheet on hand, I thought I would try to make one on my own. The instructions on how to make a wonder box were already on the Internet ( http://www.iwillprepare.com/cooking_files/Wonder_Box.htm ), but I was intrigued by the Wonderbag design (it looked a little simpler!) and decided to try to make one of those.

The first step was to obtain and shred the packing peanuts. I asked family members to save them for me, and I soon had enough—about five plastic shopping bags filled and tied off. I took the precaution of checking to be sure that they really were made of polystyrene and were not the new biodegradable ones that dissolve in water! At first, I was unsure of how to go about shredding them without making a tremendous mess, but after trying a couple options, I discovered that I could hold several peanuts between my two palms, insert both hands into a pillow case, and roll the peanuts between my hands until they broke apart. Any pieces that were still too large were gathered up and rolled again until they were small enough to resemble the balls that go into bean bag chairs. This kept most of the mess contained inside the pillow case.

Now that I had my filler done, I needed to make the bag to put it in. This meant designing my own Wonderbag-style pattern. I started by measuring the pot that I would generally use: a ten-inch-diameter pot about five inches deep. You can use whatever sized pot you like, but it must have a lid and not have a long handle. I placed the end of the measuring tape at the bottom edge on one side of the pot and went up the side and over the lid until I reached the center of the handle on the top. This gave me a measurement of eleven inches. I doubled this number and went to make a paper pattern of a large semi-circle with a radius of twenty-two inches. I used paper from an end roll of newsprint which I had obtained from the local newspaper, but several sheets of newspaper ads can be taped together to form a large enough sheet of paper to work with if other options are not available. The simplest way to get an even semi-circle is to anchor a pre-measured piece of string at the center point along the edge of the paper and attach a pencil to the other end. Keeping the string taut, trace an arc from one edge of the paper to the other.

As far as I can tell, the Wonderbag is formed of a center circle with separate sections radiating from it, so I began by marking a smaller semi-circle from the same center point as the larger one. I determined the size of this semi-circle by measuring the radius of the bottom of my pot and adding an additional inch. After I had drawn what would become the center circle, I got a protractor to help me in dividing the outside edge into five equal sections. Placing the protractor at the center point on the pattern, I made marks on the pattern at 36, 72, 108, and 144 degrees (I began on the right side in my photo!). Then I used a yardstick to draw lines on my pattern from the edge of the center circle to the outside edge of the paper. Now that the pattern was complete, I turned my attention to the fabric.

I needed to have a large enough piece of fabric to make two circles that were each forty-four inches wide. I knew the fabric needed to be fairly thin, and since synthetic fibers melt in high heat, I also knew that the fabric needed to be made of a natural fiber. I had a sheet that had been given to me that was probably large enough to have cut both circles from, but the fiber content was only half cotton and the rest was synthetic so I determined to use it for the outside of the bag only. If I had had access to forty-five-inch 100% cotton fabric, I would have purchased that, but the cheapest expedient to hand turned out to be another sheet that, while not 100% cotton, was a 60/40 blend. I decided to work with that. I folded both of the sheets in half and placing the pattern with the straight edge on the folds, cut through all the layers. This gave me the two circles that I needed. Using a pencil, I began transferring the lines on my pattern to the lighter of the two pieces of fabric. By folding the pattern along the lines I had marked on it, I was able to place the pattern on top of my fabric and trace a dashed line along its edge onto the fabric.

After I had transferred all the lines, I began sewing the two circles together. I stacked the two circles of fabric wrong sides together and stitched the smaller center circle, remembering to leave an opening for filling it. After I had added the filler to that section, I stitched the remainder of the seam closed and began stitching along the lines that radiated out from it. Being sure to backstitch the beginning and ending of each seam to lock the stitching in place, I began each seam at the center circle and stitched straight out to within two inches of the outside edge. Here I turned and began sewing parallel to the outside edge until I was within an inch and a half of where the next seam would go. This formed the outside sections and left an opening in each one for them to be filled.

Now that the sections were all sewn in, I could begin the process of filling them. I used a funnel (cut from the top of a two-liter soda bottle), and a plastic container to carefully add the filler to each section. I did not pack each section so full as to be tightly stuffed, but I did fill each one moderately full and pinned the openings closed. Though the lighting in this photo is a little odd, I chose it because it does show what the sections should look like. When I was happy with the level of the stuffing, I finished sewing up all the seams.

The next step was the drawstring. I simply made a long, thin tube from some fabric cut from my sheet and turned it so that the raw edge was on the inside. If you would like to skip this step on your own bag, simply use the cording of your choice. To make the casing for the drawstring, I first had to make an opening for the string to pass through. Working with just the outside layer of my bag, I made a cut from the outside edge straight down toward the existing seam. I stopped just short of the seam and then, turning the raw edges under, I stitched them in place so that they would not unravel. This made a V-shaped opening in the outside layer of fabric. To complete the casing, I folded the edge of the inside fabric down over the outside fabric and stitched it in place. Then I threaded the drawstring through.

Now that the basic bag was completed, the last thing to do was to make a “lid” for it. This was very simple. I just had to cut out, sew together, and stuff two more circles that were a little larger than the circle in the bottom of my bag. Using the measurement for the bottom circle, I added an additional inch and a half to all sides and cut it out. Putting right sides together, I stitched them together, leaving an opening so that I could turn it right-side-out. After it was filled, I sewed the final opening together and my bag was complete. Now all I had to do was to test it.

I had a package of fifteen bean soup on the shelf, so it became my test project. It called for letting the beans simmer for two and a half to three hours, so it was an excellent one to test! The standard “recipe” for things with a long cooking time seems to be to bring the food to a boil and let it boil for twenty minutes. Then it is transferred into the bag where it stays covered for twice the amount of simmer time normally called for on the package. I let the beans soak overnight, and after pouring off that water, I added my ham, the ham stock, and all the other ingredients I wanted it to have, even the ones that the package recommended putting in toward the end of the cooking time. I made sure there was not a lot of air space left at the top of my pot, since this reduces the effectiveness of the bag. I brought the soup to a boil, and leaving the lid on, I let it boil at a good clip for twenty minutes. Then I immediately transferred it into my bag, put the bag “lid” on, and cinched the bag closed. I felt around for hot spots and adjusted the stuffing to fill in anywhere I could feel heat escaping. Then I left it on the counter (never leave it on a surface that is a good conductor of heat) and waited for five hours.

Finally, the five hours were up! With anxious fingers, I loosened the drawstring, and removed the cloth lid. I lifted the silver lid of the pot and the steamy aroma of the beans rose to meet me. I fished out some of the beans with a spoon and tasted them. They were wonderful! They were completely done and tasted great! Now I only had one problem. I had put the beans into the pot at about nine o’clock in the morning thinking that I wanted to have extra time to let them finish if need be, since the cooking times for the bag vary somewhat depending on what you want to cook. Now I had another three and a half hours until dinner time, and the beans were ready to go. I decided to close the bag back up and see what would happen.

At dinner time, I opened the bag up and without reheating it, I served the soup—over eight hours after the last heat had been applied to them. They were excellent! This was fix-it-and-forget-it at its absolute best. The bag had allowed me to put twenty minutes of electricity into something that normally took two to two and a half hours and kept it hot without scorching or burning for over eight hours! It was amazing!

This project really highlighted the issue of faith for me. I had invested hours of my time into gathering materials, designing a pattern, and putting the whole thing together—all because some individuals on the Internet said that I could save energy and money using a heat retention oven. Even after I had made the bag I had to continue trusting their witness and could not even peek to see how the food was getting along, or I would have allowed the heat to escape and the experiment would have failed! To be so close and yet still not know if the project was a success or not was hard! How wonderful to know that my faith in Christ is not like an Internet project, subject to human error and faulty equipment! It is a sure expectation that the God who promised me an inheritance in His family can and will one day fulfill His promise. I need only take Him at His word. I was reminded of the verses in Hebrews where Christians are encouraged to be “…followers of them who through faith and patience inherit the promises…” for “…without faith it is impossible to please him [God]: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him” (Hebrews 6:12 and 11:6). I had gone through all the work and effort to make this oven based solely on the testimony of others, even though it may all have been a hoax, or their instructions may have been faulty. How much stronger then, should my faith be in the sure promises of a perfect God Who cannot lie! Have faith, fellow believers, for through faith and patience we shall inherit the promises!

 

December 6, 2012 update- I had been using this bag for several months to make sure that it worked well before I posted it to my blog site. However, I just discovered another advantage to the bag-style over the box-style heat retention oven. I used my bag the other day with soup that I was taking to a function at another location. My husband drove and I held the bag with it’s enclosed pot on my lap. I spent my time trying to compensate for the hills, curves, and stops to keep the liquid in the pot, which I could not see, level. I was pretty sure there was no way I would be able to arrive at my destination without having a fairly good-sized mess inside the bag, and thought that I would soon be testing to see how well it would clean up. (I was going to try hand washing it and let it air-dry.) Upon arrival however, I was surprised to see that there was no mess in the bag at all! Nothing– not even a line to show where the rim of the pot had been! The only explanation that I could come up with is that the drawstring design of the bag puts pressure on the lid and helps it stay sealed; a feature which the box-style oven does not have.  :)

 

 

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45 Responses to DIY BAG-STYLE HEAT RETENTION OVEN FROM UPCYCLED MATERIALS

  1. I love that you did this – I’ve been thinking of trying to duplicate the wonderbag design as well as I thought it more elegant than the wonderbox. Not sure when I’m going to find the time, but you’ve given me my next sewing project!

  2. Maria Grace says:

    Thank you for your detailed description of how to make this wonderful Wonderbag! I looked around for a pattern and found your full and excellent instructions. I have made the bag but can’t see where to put a picture of it on this website. I have put it on facebook! I look forward to cooking with it! THANK YOU very much! Maria

    • I am so glad that someone else has profited from these instructions in addition to myself! I wish I knew how to have you upload a photo directly, but I am better at crafting than blogging! All the same, I hope your cooking experience is as good as mine has been.

  3. Pingback: Aires de cambio Cocinar aprovechando el calor: haybox, wonderbox y wonderbag

  4. Julie says:

    I too am so glad you took the time to share your talent in producing a pattern for the wonderbag. I just finished making my first bag and will be trying soup tomorrow. My husband says it looks funny but I find it absolutely adorable! I have already made and gifted a wonder box to a friend and can’t wait to make more bags for Christmas gifts. Thanks again!

  5. Jezebel Charleville says:

    I did some thinking and this is what I came up with!

    http://www.menards.com/main/building-materials/insulation/loose-fill/5-cu-ft-styrene-shredded/p-1934672-c-5777.htm

    As it is jsut the same thing as packing peanuts, less expensive and already shredded! It also has no direct contact with food, although after further research it doesn’t seem to contain any harsh chemicals. If you cannot find it already shredded you can buy the rigid board kind for like $5 for a 4′ x 8′ sheet. Grab a couple kids and put them to work!
    Also what if you used a more waterproof material for the inside in case of leaks or dribbles :)
    I am not sure if putting the pot in a small trash bag before putting it in this is a good idea. Not sure how hot it really gets. Need more research.

    • This is a material that I am not familiar with, but might prove to be an excellent substitute for the packing peanuts. The reason that I used packing peanuts here is because my blog is about recycling things that you might already have on hand. Since the pot is removed from the stove at a boil, I think it would melt a trash bag, but if there are dribbles, I have successfully washed my bag and let it air dry.

  6. Lynn says:

    Hey, I’m a 15 year old with not very much money and I made this for my mom for christmas with a bag of packing peanuts I found in the basement and some extra fabric. My mom made some soup this morning and the pot was still too hot to touch when she took it out! It works great! Thanks so much for the tutorial, it was really easy to follow!

  7. Lori says:

    Wow, I just discovered the Wonderbag on Amazon for the first time tonight. I can already think of so many ways to use this! One hint I have always loved is, when having a big dinner like Thanksgiving, I do my mashed potatoes ahead of time and put them in a crock pot to keep warm. Imagine using this, cause then I wouldn’t have to wash that big heavy crock pot! I would love to give them as gifts next Christmas.

    • I think this would be a great way to use the bag. The bag is wonderful at keeping things cold as well as hot. This means that you can put frozen items inside it for a long car trip and find them frozen on the other end of the trip -very handy if you are transporting ice cream!

  8. Katie says:

    Thank you so much for doing all the leg work about supplies and etc, great tutorial! I just discovered the Wonder Bag tonight and LOVE the idea of making my own! Thanks for sharing! Also, bravo to Lynn! What an awesome gift for your mom! Those are the best presents, in my opinion (as a daughter who made most of her gifts growing up, and still do for my friends nowadays)!

  9. Anonymous says:

    if worried about spills I may try to line the bag with foil or placing pot inside a foil baking tray.

  10. What a neat article! I’m still going to save my money and buy a wonderbag because for everyone one purchased the makers send one to a family in Africa. But its nice to know its so simple.

  11. Anonymous says:

    Can you use barley for packing material instead? I know that they use it for home made magic bags and such and was wondering if it would work in place of the packing nuggets.

  12. Marilyn says:

    My friend and I stitched up several of your wonder bags according to your directions,but we’re unable to use the styrofoam peanuts. They became so filled with static electric as we tried to crumble them that they clung to everything,,,,,,,,,arms, hands clothes and became un workable to use for stuffing. How did you over come this problem? Or is it just this ultra dry California air? We tried rice, but it is too heavy. Used hamster bedding successfully but would have preferred to recycle the styrofoam
    Thank you for any advise.

    • I don’t think it is your California air. I have done several projects with the Styrofoam packing peanuts and have dealt with the static on each one, so I can sympathize with your description! :) Two options come to mind at this moment. First, I would try completely enclosing the peanuts in a pillow case (close the opening), and try to break them up from the outside. This means working through the fabric of the pillow case, but it does keep down the mess. The other option you can try is to spray the pillow case and your sleeves and hands with a mild solution of diluted liquid fabric softener. If anyone has any other methods of overcoming the static electricity problem, please leave a comment and let us know!

      • Carmenrella says:

        I had a spray bottle filled with water that I sprayed on my hands and arms before crushing the styrofoam peanuts. It kept the mess down considerably. I also had my small vacuume cleaner neary.

  13. Cris says:

    Al least clear instructions to make it!
    Thanks a lot!
    Cris

  14. Thanks for sharing your design! I belong to a community of singers that holds singings and conventions with a potlock at the event, so having a way to keep food hot has been a long-time issue for everyone. The Wonderbag is awesome, but for people like me with a few sewing skills, the option to make one myself is perfect!! I’m going to try using layers of wool to keep it warm and see if that works.

    • I believe that wool will do fine as an insulator. The only thing that might be more difficult with wool would be cleaning it. I wonder if it would felt? If you do try the wool, I would love to know how well it works!

  15. Susan Sunde says:

    I’ve seen lots of pictures of the Wonderbag and I have to say, yours is certainly the prettiest!

  16. Pingback: Wonderbag. Ho della cottura nel cuscino | ehabitat.it

  17. Kathy Borst says:

    Another thing these kinds of bags are good for is making yogurt. I make a gallon at a time in quart jars. I add a jar full of water that’s at a slightly higher temp to help balance out the little bit of heat loss that will occur. It works great. Love your design. Would be interested to know if anyone has tried wool.

  18. Katie says:

    It’s so great to read your experiences with making this! Can you please re-explain the part about making the drawstring tube? I have read it several times but still don’t understand it, not even the part about skipping that step. Are you making this tube with a separate piece of fabric than the main circle? How does it attach to the circle? I’m confused.

    • Sorry! I did not mean to be vague. Though there are many different ways to make fabric tubes, this link shows one method that does not require any special tools and one that I have used quite often, I did cut a long strip of fabric (about 90 inches long) from the side of my sheet to make this tube. As in this tutorial, I did not close off the ends of the tube, I just made a knot in the ends after the tube was turned right-side-out. I hope this helps, but if you have more questions, please do not hesitate to ask! :)

      • Katie says:

        Thank you for the explanation. I was still confused after watching the video, wondering how you stitch the tube to the circle, but then I went back up to your instructions and enlarged the photo of the drawstring. After seeing that photo up close, it dawned on me that the tube you are referring to IS the drawstring, NOT the tube that the drawstring passes through. Big eureka moment! Then I re-read the directions and figured out what you are trying to convey—–to make the drawstring passage hole, itself, you first make the V by cutting in from the edge, then turning under the edges and stitching them, and then you turn the edges of the whole circle under and stitch them together, and draw your drawstring (or tube-drawstring) through. Doh!

      • Katie, thank you for taking the time to write down what was confusing you. Others may have experienced the same confusion and your written explanation may make it easier for them. Writing down how I made a project is much more difficult for me than figuring out how to make it, so sometimes, what is clear to me (and my proof reader!) is not clear to everyone. I appreciate your help! :)

  19. Thanks for your instructions, they are very good. I made one tonight, so I could cook a pot of pinto beans. I think I may have put more stuffing than necessary but it is cooking away. My question is do you ever feel a bit of heat through the pillow? I did about ten minutes after I tied it up, but ten minutes later there was less. Is this normal?

    • Yes, it seems to be normal that there will be minimal heat loss. Right after I place my pot into the bag and close it up, I feel around for places where I feel heat escaping and mold the stuffing more firmly into those areas. Even so, I know there is some heat loss because the counter under the bag is warm when I finally move the bag later in the day. Leaving the bag on a surface that does not conduct heat well (like wood) will help. I am glad you found the instructions helpful for you. I hope your cooking experience with your new bag is successful!

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  22. Jane says:

    I know the Wonderbag people donate one to an African family for every one sold so I have made one and am about to donate one to a food bank so that someone local to me will benefit.

  23. beviboo says:

    I hope this is ok… I pinned your diy blog about making a “wonderbag”… great idea! Thank you.

  24. Julia Gonzalez says:

    Thank you for sharing this!! I would like to buy a Wonderbag but they are a little pricey. This was so helpful!

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