The first time I encountered haybox cooking was when I watched the Wartime Farm a few years ago, but since I’ve encountered it in many other contexts. It’s an extremely energy effective way of cooking, which has long since been forgotten. However, it might interest the modern enviromentalist (or survivalist, for that matter).
“A haybox? What the blazes is a haybox, and how do you cook with it?” you might ask.
The principle is simple. The food is first heated on an ordinary stove. You then put the hot pan inside an insulated box and let it cook using the existing heat in the food. So instead of having to keep adding heat during the entire cooking process, you can turn off the stove after getting it properly hot, and simply let it finish by preserving the heat. Thus, it only takes a fraction of the energy in order to make a meal, making it a great energy (and cost) saver. Like the modern slow cooker or Crock-Pot™, it also has the advantage of managing on its own, which means you are free to pursue other activities while your meal is getting ready. You could say it works like an inverted icebox, or like a king-sized thermos.
During WWII, when there was a shortage of fuel in the UK, it was widely promoted as a rational way of cooking, but the haybox technique was used long before the 1940s. Probably, variations of it have been used since times immemorial, but it seems to have had a surge in popularity during the early 20th century, when commercial varieties were sold. There were also several cookbooks produced with recipes for haybox cooking. In The Bachelor Girl’s Guide to Everything by Agnes M. Miall (1916), it is promoted as especially well-suited for bachelor girls in cramped lodgings who do not have time for traditional cooking, being away at work all day. For someone who only had a small cooker, running on expensive gas, this was clearly a brilliant way to save money, as well as a convenient way to cook food, or keep water hot overnight for washing yourself with in the morning.
Agnes Miall gives thorough instructions on how to build a simple haybox yourself at small expense. You need a wooden box of appropriate size, which you line (including the lid) with brown paper and then with felt. The idea is obviously to form an outer insulation shell to keep any heat from seeping out through cracks and wooden planks. Having layered the bottom with a three-inch layer of hay, you then put it the pan or pot you intend to use and pack hay all around it. You should pack it densely and make sure the hay is pressed in a way that ensure it stays in place when you take out your pot. For the top, you make hay cushion, three inches thick, of woollen fabric. Margaret Mitchell, in The Fireless Cook Book, says that it may be spruced up on the outside with hardwood, a coat of paint, or covered in chintz.
Obviously hay isn’t your only option as insulator, though it was probably one of the cheapest and most easily-obtainable materials available in the early 20th century. But if you had wool, cotton, sawdust or paper available instead, those could be used in exactly the same way according to Margaret Mitchell, though some materials will obviously require special construction techniques.
So what can you cook in a haybox? In general, anything that is cooked through boiling or simmering. Soups, stews, boiled potatoes and vegetables, macaroni, stewed fruit and porridge are all recommended in the books I’ve read. It’s also great for your steamed puddings (including graham puddings, which is one of the recipes given by Margaret Mitchell). One thing I would never have thought of, however, is the above-mentioned use for it as a container for hot water for washing yourself, your clothes or your dishes, which must have been really handy in an era when you couldn’t just turn on the tap for hot water, and when rooms were often terrifyingly cold in the morning. Much easier to get out of bed and wash yourself when you have hot water already waiting!
A caution though: bacteria. Food kept warm but not hot is a great breeding ground for nasty bacteria that can, if you’re unlucky, even prove fatal. You can heat the food on the stove to boiling point after cooking and before eating to reduce the risk of food poisoning, and a thermometer can help you keep track on how the cooking in the box progresses and when it hits the “danger zone” through cooling. This is obviously where modern slow cookers prove vastly superior to the old haybox, but nevertheless, it’s a pretty genius way of cooking. I think the early 20th century deserves a shout-out for utilising it so cleverly.