1. Avoid leaving fingerprints and smudges on the inside surface
of the cooker. Keep the inner surface clean and shiny by wiping
occasionally with a wet towel. This will keep the Solar Funnel
Cooker working at its best.
2. If your funnel gets out-of-round, it can be put back into a
circular shape by attaching a rope or string between opposite
sides which need to be brought closer together.
3. For long-term applications, a hole in the ground will hold
the Funnel Cooker securely against winds. Bring the funnel
inside or cover it during rain storms.
4. The lids can be used over and over. We have had some trouble
with the rubber on some new canning-jar lids becoming soft and
"sticky." "Ball canning lids" do not usually have this problem.
Running new lids through very hot water before the first use
seems to help. The lids can be used over and over if they are
not bent too badly when opened (pry off lid carefully).
5. The jar can be suspended near the bottom of the funnel using
fishing line or string (etc.), instead of placing the jar on a
block of wood. A plastic bag is placed around the jar with air
puffed inside, as usual, to trap the heat. The suspension method
allows sunlight to strike all surfaces of the jar, all around,
so that it heats faster and more evenly. This suspension method
is crucial for use in winter months.
6. Adjust the funnel to put as much sunlight onto the cooking
jar as possible. Look at the jar to check where the sunlight
is hitting, and to be sure the bottom is not in the shadows.
For long cooking times (over about an hour), readjust the position
of the funnel to follow the sun's path. During winter months,
when the sun is low on the horizon (e.g., in North America),
it is helpful to lay the funnel on its side, facing the sun.