Sandblasted, then anodized: how aluminium gets its skin
The matte, silky surface on a machined part is not paint and not luck - it is two processes, in a fixed order, each doing one job.
Fresh off the machine, aluminium is shiny, smudgy and soft-skinned. The surface you actually want - matte, even, fingerprint-proof - is built in two steps.
Step one: blasting
The part is blasted with fine media - glass bead for a soft satin, aluminium oxide for a flatter, greyer matte. Blasting does two things at once: it erases tool marks into one uniform texture, and it peens the surface slightly, closing pores and edges. Media size decides the mood of the finish; pressure and distance decide its evenness. Ten seconds too long in one spot reads as a cloud you cannot unsee under raking light.
Step two: anodizing
Anodizing is not a coating - it grows the metal's own oxide into a hard, porous layer, electrochemically, a few microns deep. The pores take dye (or stay clear), then get sealed in hot water. Two grades matter for objects like ours:
- Type II - the standard decorative-and-durable layer, 5-25 microns. Takes colour beautifully.
- Type III (hardcoat) - grown thicker and denser for wear parts; greyer, tougher, less colour range.
Why the order is fixed
Anodize first and blasting would cut straight through the oxide. Blast first and the anodize follows every detail of that texture, hardening it in place. The finish you feel is therefore the blast profile, made permanent.
A clear-anodized, bead-blasted part keeps the exact colour of the raw alloy - just deeper, calmer and about as scratch-resistant as glass. That is the default skin here: nothing added, everything fixed in place.