What you need to have
The fire is ignited with a plastic bag, you can use food packaging. In the forest you should find dry bark, grass, branches and have access to water.
The process of lighting a fire with a plastic bag
The only precondition is sunny, dry weather. By the way, if there is no water nearby, then you can use your own urine to incite, but the effectiveness will be lower.
Break off a piece of bark from a dried tree, a tinder will be prepared from it.
On two large stones, break it into a fine powder. The smaller and drier it is, the faster the fire will light. One more tip - do tinder of their dark materials, they absorb solar energy as much as possible.
First, crush the bark with a stone, and then, using them as a millstone, grind it into dust. Divide the learned amount into approximately two parts, pour them into pieces of bark.
Collect dry branches from the ground with a diameter of about 0.5-1.0 cm, and from trees break dry ones of a smaller diameter. Try to take the thinnest, this will facilitate the process of kindling.
Harvest a handful of dry grass; finding it in the forest is not a problem. If the hay is damp, then spread it in the sun and dry for several minutes. During bending, the stems should break, not bend.
Lay out the prepared materials in a flat, dry and well-lit area.
Ignition is done in the following order: first, a tinder from the bark is ignited, then dry grass, thin branches and thick branches. After that, ordinary firewood can be thrown into the fire.
This completes the procurement of combustible materials, you can begin to manufacture the lens, the success of the business depends on its quality.
Empty the food bag. It should be clean, transparent and fairly durable. Fill it up to half with water.
Tilt the bag to the side, water will collect at one corner of the bag, excess will pour out. Pick up the empty ends, try to keep its maximum number inside. The larger the diameter of the lens - the more heat rays it collects, the higher the temperature at the fixation point.
Twist the ends with sufficient force, the bag should take the shape of a sphere, try to make it have the most even surface. Tighten it gradually, do not apply too much force, otherwise the polyethylene will not withstand and will burst. If there is another bag - excellent. If not, you will have to use other methods of kindling fire.
Hold the sphere over the tinder of the bark and focus the rays on the surface of the material, make sure that water drops do not fall on the powder. After a few seconds, a haze appears, increase the kindling area, slightly shift the focus.
Pour another batch of powder on top, heat it again with a sphere. Make sure the powder smolders without a lens.
Make a tight tourniquet from dry grass and sprinkle a smoldering tinder onto it. First, cover the bark with hay, and then carefully turn everything together. Due to this technology, a small hearth will continue to smolder, and will not crumble and go out.
Cover it with grass on all sides, to increase the amount of oxygen, carefully blow into the ignition site.
As soon as an open fire appears, quickly lay the thinnest branches on top, and then a little thicker. Continue blowing into the fire until they ignite reliably.
It remains to throw large firewood and use the bonfire for its intended purpose
Conclusion
We talked about only one way of ignition using sunlight. A lens can be made not only of a spherical shape from a bag, there are options for making flat ones, but using them to kindle a fire is more difficult.
