Clear concave lids when filled with water can become solar fire starters. Any water lens method can be achieved in essentially two ways via an open system or a closed system. I demonstrate a closed system by using an inverted 2 liter soda bottle filled with water in my video “Soda Bottle Fire Method“.

Recently I picked up an ICEE (a.k.a. Slurpee and Slushy) lid and noticed the clear concave surface. I knew that it could possibly make a lens when filled with water. In my early days of experimentation I would try different open vessels filled with water and discovered two things: water should be shielded from wind and the vessel should be stabilized and not hand held so as to avoid ripples that would prevent a usable focal point.

In pursuit of my project I decided to stabilize the lid using a screwdriver. I inverted the lid and placed a long screwdriver shaft through the middle and then taped the edge of the lid to the screwdriver handle. Then I planted the blade of the screwdriver into the ground like a stake. The tilt of the lid provided a hollow in which I poured water to effectively create a lens. Below the cup I located the focal point by placing my hand into the light cast to determine the smallest point of light and feel the heat that it generated. The best time for this effort is at noon when the sun is at it’s highest point in the sky.

I find that my favorite tinder for solar firecraft is dark compressed dry fiber because dark material absorbs heat better, the fibrous material allows air flow, the compressed material transfers the heat and provides a surface upon which to focus whereas light cannot focus on fluffy material. Strangely enough, dry horse manure tinder works well for this.

I placed the tinder at the focal point and shortly thereafter a wisp of smoke began to appear. As I waited for that moment I happened to notice a piece of charred wood close by. Knowing the dark and carbonized nature of this material I broke off a small piece and placed it on the tinder with the edge at the focal point. This expedited the formation of the coal which I in turn blew into a flame.

Once you become more familiar with water lenses it’s amazing what things you will begin to recognize as viable vessels for solar firecraft. Who knew that fast food trash could be used to generate a fire?!