Polypropylene is the safe flexible plastic for laser work: chlorine-free, it cuts with a CO2 leaving a slightly melted, smooth edge. It is the right replacement for PVC in jigs, stencils and packaging.
Settings: what really matters
PP melts before it vaporises: the right setting goes through in one fast pass. Too slow and the material melts either side of the line, the two edges re-welding behind the beam.
Air assist helps a lot here: it clears molten material and keeps the edge clean.
Engraving is unsatisfying: PP barely whitens and melts easily. Keep it for cutting and scoring.
Risks and finishing
No corrosive gas, but molten-plastic fumes to extract, and a flame risk on thin sheets: supervision needed.
Do not confuse a PP sheet with PVC. The water test settles it: PP floats, PVC sinks.
The melted edge is clean and needs no finishing. PP does not glue or paint easily: plan a mechanical assembly.
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.