Some years ago I was searching the web for new firecraft methods that I had yet to try. I ran across a video by Robb (a fellow firecrafter) on YouTube where he used aluminum foil in combination with a glass lid from a cooking pot. He rubbed a light coat of vegetable oil on the inside concave surface of the lid and then applied the aluminum foil shiny side out to the surface thus creating a concave mirror. He pointed this reflector at the sun and held tinder at its focal point for ignition.
I had tried this method a few times without success so I wondered “what would make this work?”. I decided that I needed a shinier surface so I went to a “dollar” store and bought a Mylar balloon. After trimming off the edges of the balloon and separating the resulting sheets I repeated the process of oiling the lid and placed a Mylar sheet shiny side out onto the surface and WOW! Smoke appeared so fast that it was almost scary! I used a piece of rolled-up newspaper for the tinder. When using tinder for solar fires it is best to use dark fibrous material so if you use newspaper, make sure to focus on a dark print area for best results.
Using Mylar gave me great results! But, I will continue my quest of using aluminum foil as a reflector to achieve a coal. Quoting from the film “The Edge”, I am admonished with this: “what one man can do, another can do”. Fortunately, right now is a good time of year to achieve my goal as the sun is at it’s highest point in the sky and should give me the best results for this solar firecraft method.