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11.11.2023 13:46, Pavel Kotov
One of the interesting innovations in the new Apple MacBook Pro is the Space Black color of the case – the radical black color of the matte surface is not only an aesthetic, but also a practical solution. The manufacturer claims that there are no fingerprints left on such a surface, and iFixit We decided to test this using equally radical methods – by getting our hands dirty with Cheetos snacks, which are famous for their soiling.
Image source: ifixit.com
The matte texture of the aluminum body of the Apple MacBook Pro is achieved through anodizing. This is an electrochemical process in which an oxide layer is “grown” on the surface of an aluminum sheet – microscopic hollow bumps that act as protection. In Apple’s case, given its traditional approach, this is done not only for practical purposes, but also for aesthetic effect. To create different colors, explained the expert invited by iFixit, various dyes can be added during the etching process; it takes a lot of effort and a lot of trial and error to achieve a consistent result – it’s a lot of research and development work. But achieving radical black is more difficult than any other color.
We see the color of objects due to the movement of light – when it falls on the surface of an object, one part of it is absorbed and the other is reflected. Thus, a tree appears green because its leaves reflect light primarily in the green part of the spectrum and absorb light in other wavelengths. An object that appears black reflects some of the light, absorbing all visible wavelengths approximately equally. Light can be reflected specularly or diffusely. With specular, all rays are reflected from a smooth glossy surface in one direction and create highlights perceived as white; and from the uneven matte they are reflected at different angles, helping us to see the true color, and not white highlights.
The Space Gray case was an important step for Apple towards creating a black version. Using anodization, the glossy aluminum sheet was turned into a diffusing surface that was pleasant to look and feel, but even the dye did not help achieve a radically black color – the surface was still perceived as gray rather than black. Apple came to the rescue with an etching process, which is defined as the removal of the surface layer of a material using chemicals – in this case, it helped make the microscopic protrusions of the oxide layer even deeper and more irregular. Such irregularities scatter the incident light even more, reflecting the rays in even more directions.
This is clearly visible in comparison under a microscope: due to the absence of etching, the Space Gray version looks brighter, since its surface is smoother and the set of reflection angles is more uniform; Space Black, on the other hand, gives a more muted color because the reflected photons are scattered more strongly. This was illustrated even more clearly using the Olympus OLS 4000 LEXT laser measuring system: the image of the Space Black surface showed brighter blue and green spots, indicating deeper recesses and higher protrusions than Space Gray.
And it seems that these measures had a beneficial effect on the practical side of the issue – the radically black matte case became less easily soiled. When a person leaves a fingerprint on the surface of an object, sweat and oil from the finger remain on this surface and spread over it. The glossy surface allows them to spread more freely, the marks on the contact lines stretch, and the print becomes visible to the naked eye. The grooves and ridges on the Space Black make it harder for contaminants to “trickle” in: sweat and oil don’t transfer as easily, and what does transfer flows much less easily. The result is either a weaker print or no print at all.
iFixit testers tested this in practice: the imprint of a relatively clean finger on the Space Gray surface came out clearly – a real gift for a police forensic scientist; into the Space Black case did not allow leaving a clear, continuous mark. An extreme experience with fingers that were deliberately stained with Cheetos snacks confirmed the effectiveness of the matte case – fine particles seemed to only increase the beneficial chaos on its surface. Apple traditionally keeps the features of its developments secret, so additional protection measures should not be ruled out: a polymer or oleophobic coating could be applied to the case.
