Raw Aluminum: Dark Mark

Bare aluminum is hard. It reflects 1064nm and conducts heat away too fast. You have three options: dark frosted etch, brush-then-mark, or use a marking spray.

Option A: Dark frosted etch

Slow speed, high power, long pulse. You get a frosty/gray mark, not pure black, but it's permanent and looks great on machined parts.

Param	Value
Speed	200-400 mm/s
Power	60-90%
Frequency	20-50 kHz
Pulse width	200 ns
Passes	2-4

Option B: Marking spray (CerMark / TherMark / molybdenum-based sprays)

Spray a thin even coat, let dry, mark, wipe off residue. Gives a true black bonded mark.

• Speed 500 mm/s, Power 60%, Freq 50 kHz, Pulse 200 ns.
• Single pass; test before scaling.