HDF is high-density MDF: same material, compressed further. Harder, smoother and more consistent, it engraves with crisp contrast and cuts with very clean edges — at the cost of higher power needs and heavy smoke.
Settings: what really matters
Allow roughly 10% more power than MDF of the same thickness, or 10% less speed. When engraving, 45% at 2,900 mm/min with a 20 W diode gives a crisp line on the smooth surface.
For cutting, HDF gives remarkably straight edges, but very dark ones: air assist and a single slow pass limit the charring. Two fast passes give a wider, dirtier edge.
Common thicknesses and pitfalls
Common thicknesses: 2, 3, 4 and 6 mm. 3 mm HDF is the classic support for puzzles, models and painting panels.
Pitfall: the urea-formaldehyde glue in the panel. It smokes heavily, leaves a yellowish film on the lens and gives a persistent acrid smell. Effective extraction is not optional.
Risks and finishing
HDF smoke contains formaldehyde: only use this material with outside extraction or a carbon filter in good condition, and air the room after the batch.
For finishing, cut edges are porous and drink paint: seal them with primer or diluted glue before painting. An eraser is enough to remove surface soot.
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.