Painting your cookware
There are lots of choices of cookware - glass, aluminum, stainless, cast iron. But to get the best performance you need black - dull black, on the outside surface.
Customers report using "high heat" BBQ paint to darken their cookware. This is not neccessary
I use the 99 cent stuff I find at WalMart. Flat black, inexpensive, and most importantly "non toxic when dry"
Regardless of the paint you use, let it cure in the solar cooker for a couple of days - until all the paint odor is gone. To get rid of the last remnant of paint odor, wash the now "cured" pot with soap and water.
Of course you paint the outside of the pot only.
I use the flat black on my cooking vessels, including the handy mason jars I am working with now.