Dehydrating food is a great way to reduce the weight of your food while backpacking. To do this, you can buy already dehydrated foods from stores, such as Wilderness Dining, or you can dehydrate them yourself at home. You can buy expensive dehydrators, costing even up to $100, or you can build your own, for about $10.
– Foil covered Foam-core insulation board
– Foil flue tape (Duct tape might also work)
– Ceramic closet light fixture
– 100 watt light bulb
– Extension cord
– optionally a clip on switch
– Electricians tape
– Zip-lock baggie
– Twist caps for wiring.
– Cheap foil cookie trays – thinner is better
– Wire Coat-hangers
1) Determine how many trays you want to dry at a time.
2) (top and bottom) – Cut two pieces of insulation board the dimension of your cookie sheets + 1″ each side for air flow + 1″ each side for construction purposes as detailed below. This is the top and bottom.
3) (long sides) Cut two pieces of insulation board dimensioned by length of the bottom piece and height of 6″ for clearance with heating element (light bulb – see below) + 1″ per tray desired in use.
4) (short sides) cut two pieces of insulation board dimensioned by width of bottom piece – 2″ for construction overlap(see below) for length and height of 6″ for clearance with heating element (light bulb – see below) + 1″ per tray desired in use.
5) Assemble. Placing the long sides ontop of the bottom at 90 degrees to form the sides use the flue-tape to attach them. Make sure that the flue-tape contacts the foil on both pieces as it will peal away from the cut foam easily. With both long sides in place, insert the short sides between long sides and bottom and tape. You may want to tape the inside seams also. Attach the lid with tape on one long side only and use two or three thicknesses for a hinge. Now you have a very light well insulated box.
6) Wire. Find the approximate center of the bottom and poke a hole with a phillips screwdriver to allow a wire to thread thru. Cut the socket end off the extension cord and send the raw wires through the bottom of the dehydrator. Assemble the ceramic light socket ( use a ceramic ceiling socket because it will be getting hot.). Make sure to use the twists to cover the exposed wires. Cover the foil where the socket will sit down on the bottom insulation board with a bunch of electricians tape and the zip-lock baggie for electrical insulation. You don’t want the foil of the box to become electrical! Put the clip-on switch on the cord somewhere convenient outside the box. Put a lightbulb in the socket and light it up. If there are no sparks, fumes or blown fuses you are good to go!
7) Put in the racks. Find where on the long sides the height of the bulb +1″ is and poke some coat-hangers in through the box and out the other side. Continue this vertically for each layer you wish to dry.
Tips on usage:
1) Stagger the racks such that the airflow path weaves through not around. This can be done by sliding alternate racks up against the alternating sides / corners.
2) Get a stove thermometer and determine what heat you reach with different wattage light bulbs. This will allow some control over the drying time and temp.
3) Get some fiberglass window screens and rinse them in bleach for sanitation and youre drying time will be reduced vs using the cookie sheets.
4) If you are consistantly getting too much heat you can poke some holes in the bottom edge of the sides or the bottom but be careful not to weaken the structure or cause a thermal updraft that might bring in humid air. (I use mine in the celler and a hole drawing from the floor would not be a good thing for my food or the drying process).
5) You will want to run with the top open at-least since you need to let the water out.
I find that with a 100 watt bulb, the top propped open with a screwdriver and a few holes along the long sides at the bottom, I can dry a can of refritos in an over-night. My dehydrator runs around 180 degrees F consistantly in this configuration. I was above 200 degrees F with the unit sealed. (lid down and no holes in the sides).
I have considered adding a simple fan from Radio Shack but so-far don’t see the need.
Total cost for this was around $10 – mostly the light fixture and extension cord.