Acrylic (also known as Plexiglas, Perspex, or PMMA) is one of the most rewarding materials for CO2 laser processing. Its excellent absorption of the 10.6 μm wavelength produces clean, precise results with minimal charring. Engraving creates that signature frosted white appearance against clear or colored backgrounds — perfect for signs, awards, illuminated displays, jewelry, and custom gifts. In 2026, with advancements in software like LightBurn and machine precision, achieving pro-level frosted engravings is more accessible than ever.

Note: These techniques focus on engraving (surface frosting or shallow texturing), not cutting. Cutting requires higher power, slower speeds, and strong air assist for flame-polished edges.

Choose the Right Acrylic Type

• Cast acrylic → Best for engraving. Produces a bright, uniform white frosted look due to its manufacturing process (poured into molds). Ideal for backlit signs or detailed photos.
• Extruded acrylic → Better for cutting (cheaper, smoother edges when cut), but engraving often yields a grayish or unclear matte finish — avoid for high-quality frosting.

Always verify with your supplier; cast is typically labeled as such and costs more.

Essential Setup and Preparation

1. Lens choice — Use a 1.5–2.0 inch (38–50 mm) focal length lens for the tightest spot size (~0.1 mm) and finest detail.
2. Focus technique — For classic frosting:

• Focus exactly on the surface for crisp lines.
• Defocus slightly (raise the bed ~1–2 mm or lower the lens) for a softer, blended frosted appearance that hides individual raster lines.

1. Masking — Remove protective film/paper before engraving clear/cast acrylic to avoid melted residue embedding in the frosted area. For cutting, leave it on to protect from smoke marks.
2. Air assist — Low to medium (10–30 psi) to clear vapor without blowing molten material around. Too high can scatter residue and ruin the frost.
3. DPI/LPI — 300–600 DPI (or 250–400 LPI) for most work. Higher (500+) for ultra-fine detail; lower (200–300) for bolder, coarser frost.

Recommended Starting Settings for Engraving (2026 Guidelines)

Settings vary by machine wattage, lens, acrylic thickness, and software (e.g., LightBurn, RDWorks). Always test on scraps — start conservative and adjust.

For surface frosting (0.1–0.5 mm depth, classic white look):

• 40–60W CO2 laser:
• Power: 15–25%
• Speed: 300–400 mm/s
• Passes: 1 (multi-pass for deeper if needed)
• 80–100W CO2 laser:
• Power: 10–20%
• Speed: 400–600 mm/s (or higher)
• Passes: 1
• Higher wattage (120W+):
• Power: 8–15%
• Speed: 500–800 mm/s

For deeper engraving (0.5–1+ mm, pockets or filled areas):

• Power: 25–40%
• Speed: 200–350 mm/s
• Multiple passes (2–5) to build depth gradually and avoid melting.

General rules: "Less is more." High speed + low power vaporizes just the surface for bright white frost. Too much power melts grooves instead of frosting, creating haze or clear pockets.

Example from real-world tests (LightBurn, cast acrylic):

• 20% power, 500 mm/s, 350–400 DPI → Crisp, bright frost on clear 3–6 mm cast.
• Mirror artwork and engrave from the back (reverse engraving) for protected, high-clarity results — the front face stays pristine.

Pro Tips and Techniques

1. Reverse engraving — Engrave on the back side (mirror image in software). Light shines through the front for glowing effects in backlit pieces. The engraving is protected from scratches/fingerprints.
2. Test grids — Create a power/speed matrix on a scrap sheet to dial in your exact machine/material combo quickly.
3. Avoid common problems:

• Melted/gummy residue → Too much power or no/low air assist. Reduce power, increase speed.
• Hazy/cloudy frost → Over-powered single pass. Use multiple light passes or defocus slightly.
• Uneven depth → Inconsistent focus or warped material. Ensure flat bed and even clamping.
• No frost (clear engraving) → Likely extruded acrylic or extremely low power/defocus.

1. Photo engraving — Use Jarvis or Stucki dither in LightBurn for best contrast. Lower DPI (250–300) helps blend for smoother gradients.
2. Post-processing — Gently clean with cold water and a soft brush (toothbrush) to remove vapor residue. Avoid hot water/soap to prevent warping.
3. Safety — Acrylic fumes are mostly non-toxic but irritating — use strong exhaust/fume extraction. Never leave the machine unattended.

Why CO2 Excels on Acrylic

Unlike diode lasers (which transmit through clear acrylic with poor results), CO2 lasers are absorbed efficiently, enabling controlled melting/vaporization for that iconic polished-cut and frosted-engraved finish.

With practice and test runs, CO2 laser engraving on acrylic delivers stunning, professional results every time. Start with low power/high speed, embrace reverse engraving for premium pieces, and watch your workshop output level up in clarity and creativity.