An electro-chemical process has been developed which, when applied to aluminum and most of its alloys, produces a surface which is highly absorbent in most of the wide spectral range from the near ultraviolet (0.27 micrometers) to the far infrared (125 micro-meters). Its infrared characteristics in the band from 8 to 125 micrometers are discussed in this paper, where its absorptivity and emissivity remain above 0.985. The surface is space qualified and has flown in the Skylab missions. It also withstands exposure to hydrazine (a rocket fuel), commonly used cleaning reagents, and many other chemicals. This surface is one of the most absorbing yet developed over an unusually wide range of radiation.