A hay box, straw box or fireless cooker is a cooker that utilizes the heat of the food being cooked to complete the cooking process. Food items to be cooked are heated to boiling point
Boiling point
The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....

, and then insulated
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

. Over a period of time, the food items cook by the heat captured in the insulated container. Generally, it takes three times the normal cooking time to cook food in a hay box.


Hay boxes are so called because hay
Hay is grass, legumes or other herbaceous plants that have been cut, dried, and stored for use as animal fodder, particularly for grazing livestock such as cattle, horses, goats, and sheep. Hay is also fed to pets such as rabbits and guinea pigs...

 or straw were the commonly used insulators. Pots of food would be brought to a boil and then placed in a box filled with hay or straw. Additional hay or straw would be added around and on top of the pot. Campers and hikers have used variations of hay boxes for years, heating their food in the morning and then storing the heated pot in a sleeping bag
Sleeping bag
A sleeping bag is a protective "bag" for a person to sleep in, essentially a blanket that can be closed with a zipper or similar means, and functions as a bed in situations where a bed is unavailable . Its primary purpose is to provide warmth and thermal insulation...

 or backpack
A backpack is, in its simplest form, a cloth sack carried on one's back and secured with two straps that go over the shoulders, but there can be exceptions...

. In this way a hot meal is available for eating at the end of the day.

Commercial designs based on this principle differed only in details of construction, and the kind of insulating material used. Some types were provided with soapstone
Soapstone is a metamorphic rock, a talc-schist. It is largely composed of the mineral talc and is thus rich in magnesium. It is produced by dynamothermal metamorphism and metasomatism, which occurs in the areas where tectonic plates are subducted, changing rocks by heat and pressure, with influx...

 or iron plates which were heated during the preliminary cooking on the stove and then placed in the fireless cooker either over or under the cooking pot. In these types, a non-inflammable insulating material was used. A successful home-made strategy was to take a box so large that the cooking pot when placed in it could be surrounded by a thick layer of non-conducting material, such as hay, excelsior or crumpled paper. A cushion was placed over the pot and a tight-fitting lid was placed over all.

Advantages and disadvantages

Haybox cooking can save vast amounts of fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

, but there is a risk of bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

l growth if the food items are allowed to remain in the danger zone for one or more hours. For this reason, food cooked in hay boxes is normally reheated to boiling before eating. Using a food thermometer eliminates the guesswork;
It's Safe to Bite When the Temperature is Right.

See also

  • Slow cooker
    Slow cooker
    A slow cooker, also known as a Crock-Pot or Slo-Cooker , is a countertop electrical cooking appliance that is used for simmering, which requires maintaining a relatively low temperature compared to other cooking methods for many hours, allowing unattended cooking...

  • Thermal cooking
    Thermal cooking
    A modern thermal cooker uses the concept of the Haybox whereby placing hay or straw around a cooking pot of heated food the meal continues to cook without fuel.-History:...

  • Vacuum flask cooking
    Vacuum flask cooking
    Vacuum flask cooking was introduced to the Asian market in the mid-1990s. The vacuum cooker , often called a thermal cooker in English, is a stainless steel vacuum flask. The flasks come in various sizes ranging from in diameter and tall. A removable pot, with handle and lid, fits inside the...

  • Carry over cooking
    Carry over cooking
    Carry over cooking refers to the phenomenon that food retains heat and continues to cook even after being removed from the source of heat. The larger and denser the object being heated the greater the amount of carry over cooking. After being removed from the heat source the internal temperature...

Further reading

  • Davis and Wood, Illustrated Lecture on the Home-made Fireless Cooker (United States Department of Agriculture, Syllabus 15, Washington 1914)
  • Huntington, E. H., Fireless Cooker (University of Wisconsin Bulletin 217, Madison 1908)
  • Lovewell, Whittemore and Lyon, The Fireless Cooker (Topeka 1908)
  • Mitchell, M. J., The Fireless Cook Book (New York 1909)
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