How to laser engrave and cut acrylic: settings for CO₂ and diode

Acrylic is where laser cutting gets visually impressive fast. A clean CO₂ cut through 3mm clear acrylic leaves a polished, glass-like edge that you didn't have to sand or flame polish by hand. Engraving turns the surface frosted white against the clear background. It's a material that photographs well and sells well.

But acrylic is also where laser type matters most. Diode lasers cannot cut clear acrylic — the 450nm blue wavelength passes straight through transparent material rather than being absorbed. A CO₂ laser is the tool for acrylic work.

Cast vs extruded acrylic

This distinction matters for cutting. Cast acrylic is made by pouring liquid acrylic into a mold and letting it cure. It cuts with a flame-polished edge and engraves to a bright frosted white. Extruded acrylic is manufactured by pushing acrylic through a die — it's cheaper but doesn't cut as cleanly and engraves with a faint grey rather than bright white.

For laser work, use cast acrylic unless you're specifically buying for a project where edge quality doesn't matter. The price difference is small and the quality difference is significant. Most acrylic sold specifically for laser cutting on Amazon and Etsy supplies is cast.

Cutting acrylic on a CO₂ laser

Air assist is essential for cutting acrylic. It cools the cut zone and clears acrylic vapour, which would otherwise re-deposit on the cut edges as a cloudy film. Use high air assist if your machine supports variable flow.

Engraving acrylic

Engraving acrylic produces a frosted white surface that contrasts against the clear base. The default on most machines is to engrave from the back of the piece — the frosted area is visible through the clear acrylic from the front, which gives a depth effect and a cleaner presentation because the surface stays smooth.

Flip your design horizontally before engraving if you're doing back-engrave on text or directional designs. Engrave the back, the design reads correctly from the front.

Coloured and mirrored acrylic

Coloured acrylic cuts the same way as clear at similar settings — it absorbs the CO₂ wavelength regardless of colour. Dark colours may need slightly less power as they absorb heat differently. Mirrored acrylic has a metal coating that reflects some laser energy — reduce power by 10–15% and test before running a full sheet.

Two-colour acrylic (a coloured top layer bonded to a contrasting base) is popular for signs and badges. Engraving removes the top layer and reveals the base colour beneath. The result looks like professional signage. Common combinations are black top/white base, red top/white base, and gold top/black base.

Ventilation

Acrylic fumes smell strong and are unpleasant in quantity. They're not as hazardous as PVC (which is genuinely toxic) but you don't want to breathe acrylic vapour for extended sessions. Run your exhaust and if you're doing long production runs in an enclosed space, add a HEPA filter inline. An air purifier behind the exhaust fan is a cheap addition that makes extended sessions comfortable.

The settings database has community-tested numbers for 3mm clear acrylic across most popular CO₂ machines. If you're just getting started with acrylic work, look up your machine and use those as your first test parameters before running your own grid.