Researchers at Rensselaer and Rice University have created the darkest man-made material ever, absorbing over 99.9% of light. The secret: a thin coating of vertical carbon nanotubes.

All materials, from paper to water, air, or plastic, reflect some amount of light. Scientists have long envisioned an ideal black material that absorbs all the colors of light while reflecting no light. So far they have been unsuccessful in engineering a material with a total reflectance of zero.

The total reflectance of conventional black paint, for example, is between 5 and 10 percent. The darkest man-made material, prior to the discovery by Lin’s group, boasted a total reflectance of 0.16 percent to 0.18 percent.

Lin’s team created a coating of low-density, vertically aligned carbon nanotube arrays that are engineered to have an extremely low index of refraction and the appropriate surface randomness, further reducing its reflectivity. The end result was a material with a total reflective index of 0.045 percent — more than three times darker than the previous record, which used a film deposition of nickel-phosphorous alloy.

A completely non-reflective surface would look like a two-dimensional, featureless, black shape.