Glass... is not required for the collection of solar heat. The National Physical Laboratory of Israel... has perfected a highly polished metal surface coated with a molecular-thin black layer of special paint, which absorbs more than 90 percent sunlight. The polished metal radiates very little of the heat it receives.... A south-facing wall fitted out with these plates would really "drink in" solar heat, windows, or no windows.

The Owner Built Home: A How-to-do-it Book (1972)