Two-ply plate is made for engraving: a coloured surface layer over a contrasting core. The laser removes the first and reveals the second — the material of door plates, labels and workshop signage.
Settings: what really matters
Only the surface layer, a few tenths of a millimetre thick, must be removed. Too much power cuts into the core, warps the plate and dirties the line: less is more here.
High speed at moderate power gives a crisp line. If the background looks uneven, increase speed rather than lowering power: accumulated heat is the enemy.
Contour cutting is possible with a CO2, but the edge melts slightly. For a perfect edge, use a pre-cut plate or saw the outline.
Risks and finishing
Raw ABS must never be lasered, but two-ply plates sold for laser engraving are formulated for it. Check the maker's "laserable" statement: a plate meant for a router can give off far more acrid fumes.
Smoke darkens the surface around the line: a dry, or barely damp, microfibre cloth removes it immediately after engraving.
Leave the protective film on while engraving when the maker recommends it: the result is much cleaner.
Every figure on LaserSettings comes with the machine, the laser source, the material and the thickness it was tested on. A setting published for a 10 W diode says nothing about a 40 W CO2, and a setting for 3 mm says nothing about 6 mm: check those four things before you copy any number.
Settings are confirmed or disputed by the members who reproduce them, so reliability comes from cross-checking rather than popularity. Photos of the result — cut edges, engraving shades, scorching — tell you more than a single number found on a forum.
Whatever the material, treat a published setting as a starting point: run a small power/speed test grid on an offcut, clean the lens, redo the focus, work with fume extraction and air assist, wear glasses rated for your wavelength and never leave the machine unattended.