As crazy as it may sound, ice can be used quite effectively to start a fire. This is a much harder method, which requires more time, as you will have to make a lens out of the ice; so you don’t want to try this when you’re dying of hypothermia. However, if you’re still warm, but need to start a fire, have at it.
Note: This is more of a hail mary, last chance, fire starting method. It takes a lot of practice and… even then there is a small chance of actually producing a fire from it. That being said… Here is how you do it:
Essentially, you’re going to make a lens out of the ice. So, you’ll need to cut a chunk of clear ice out of whatever river or lake you have handy. The thickness isn’t critical, although you need it to be at least a couple of inches thick. What is critical is that it be clear. Milky or cloudy ice, as well as ice that has dirt and leaves in it won’t work.
Start by using your knife to shape the ice into a round lens. At least one side of the lens needs to be convex, but the other side can be either flat or convex. All you’re going to succeed in doing with your knife is the forming of the ice, not the finishing; for that, you’re going to use your hands. Warm your hands up and then use them (without gloves) to smooth the ice and finish the lens. The heat from your hands will melt the ice enough t o remove irregularities, smooth out the surface and give it a glassy finish.
To use the ice, set it in place over a couple of logs or stones for a stand, with the convex side facing the sun. Determine your focal point by moving a large leaf back and forth under the lens. When it is determined, set your tinder there to get it started burning. The lens won’t become heated and melt from the light shining through it, although if temperatures are high enough, it won’t last for long.
The ways we just looked at use lenses to convert the sun’s light into heat to start a fire; but we can also use a reflector to harness the power of the sun. To use a reflector requires having a parabolic curve. We won’t bother getting into the details of how to create a parabolic curve right now, as that takes a lot of practice and skill but, luckily, you won’t have to create one. We are surrounded by parabolic lenses, as long as you know where to find them.
Like lenses, each parabolic reflector has an ideal focal point. This can vary from less than an inch to as much as several feet. Every reflectors focal point is different and will require testing in order to find the one that works best. Also, keep in mind that you are using the sun as your heat/light source and the sun is constantly moving so you will need to adjust the position of your reflector accordingly.
A satellite television antenna is a parabolic reflector. It is easy to determine the focal length, simply by looking at how far the collector is from the parabolic bowl. The collector is placed exactly at the perfect focal point. . A satellite dish all but hands you the focal point, but other reflectors will require a little trial and error. Luckily there are plenty of these to choose from and practice with, like: