It may happen that on a camping trip, hunting, fishing, or for other reasons of being outdoors, you were without a lighter (dropped it somewhere, ran out of fuel), and the matches all came out or got wet and became unsuitable for use for its intended purpose. How, then, to light the desired fire in order to cook food or keep warm?
Revision of things from a tourist backpack
If one of those present nearby wore glasses, then the lens from them could be used as a magnifying glass, and with it, set fire to paper, then wood chips, dry birch bark, and then branches. Then it would be possible to finally warm up around the fire, and cook food on its fire.
What can be used instead of a lens? Going on a hike, a tourist will definitely grab a spoon. That’s the replacement, at least in form. And if this is still a brilliant spoon made of chromium-nickel steel, then it is also due to the collective ability of sunlight.
True, the curvature of the spoon is uneven: it is more in the transverse direction and less in the longitudinal direction. To make the curvature uniform, bend it a little in length and bend it in width.
The degree of flexion-extension can be controlled by the reflection of your face in a spoon. When it becomes approximately uniform in any position of the spoon, the goal can be considered achieved. Such a modified spoon will more or less collect the rays of the sun at one point (focus), i.e., concentrate them.
Now we need material such as tinder, which would have the property to easily ignite. It can also be found among the things that a tourist will certainly take with him when he goes camping. We mean a roll of toilet paper, it is better to use a piece of black or dark cloth.
As you know, a black surface absorbs heat to a greater extent than white. We need a seasoned tourist bowler, or rather, soot from its bottom - a black standard, and this is what we need. Now we have everything to start making fire.
Getting fire from the sun with a spoon
We polish the surface of the spoon to shine. This can be done by any matter.
We start by making a tinder from toilet paper. We tear off from it a piece sufficient to twist a tight rod with a diameter of about 4 mm, rolling it several times between the palms in the same direction.
Then we prepare one side of the resulting toilet paper rod to set fire, more precisely, to obtain a smoldering red coal. To do this, tear off the tip to form a slightly fluffy end.
In order for the tip of the paper wick to better absorb thermal energy, apply a little soot to it from the camp pot. Now not a single quantum of thermal energy that has fallen on the blackened tip of our improvised tinder will be wasted.
Then we take the already modernized spoon, and we orient the scoop perpendicular to the sun's rays. This will allow you to concentrate the maximum amount of thermal energy at one point.
Next, we place the tip of the blackened tinder from toilet paper in the focus of our improvised lens and hold both objects motionless until the tinder lights up and a stable red corner is formed.
Do not be afraid that the light goes out: toilet paper or fabric, once lit, will not burn, but smolder, and for a long time and steadily.
For ignition, you can use dry grass.
It turned out fire.
Summary notes and tips
You can not spoil the spoon with bending, but then the process of ignition of the tinder will be longer and more difficult. Indeed, the double curvature of the spoon will form two foci with less thermal energy in each.
Any concave surface is suitable for igniting a fire: a lid from a watch, a curved lid from a can, the bottom of a glass bottle, and, after all, a lens cut out of ice. Instead of toilet paper, you can use a cigarette, dry moss, birch bark or a shred of black cloth.