Mylar is a thin, translucent, flexible PET film used for painting, airbrush and sandblasting stencils. It cuts very fast with a CO2 and survives dozens of uses, which makes it the most cost-effective stencil support.
Settings: what really matters
Very little power is needed: around 30% at 900 mm/min with a 40 W CO2 for 0.3 mm film. Excess power melts the outline and closes fine detail.
The film ripples with heat: keep it flat, otherwise focus is lost and the line becomes uneven. A honeycomb bed with suction is ideal.
Avoid metallised or gold mylar: the metal layer reflects the beam and can damage the optics.
Common thicknesses and pitfalls
Common thicknesses: 0.2 mm (very fine stencils, single or light use), 0.3 mm (everyday use) and 0.5 mm (reusable stencils, sandblasting).
Pitfall: bridges. A stencil with fully closed outlines loses its islands (the centre of an “O” falls out). Design 1 to 2 mm bridges before cutting; the laser will not invent them.
Risks and finishing
The film burns and melts very fast: never run a mylar cut without standing at the machine, and keep air assist on to avoid a flame at the pierce point.
For finishing, a quick dry wipe is enough. Clean the stencil with soapy water after use: dried paint weakens the thin bridges.
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.