How to Laser Engrave Two-Color Acrylic Signs

Learn how to engrave two-color acrylic cleanly—material selection, stable settings windows, line interval, focus, airflow, and troubleshooting for crisp lettering.


Best for 60–150W CO₂ lasers | Typical thickness: 2 mm | Goal: remove only the top cap layer to reveal the base color—without melting edges, gray haze, or residue.

Key idea: Two-color acrylic is an “engrave-to-reveal” material. You are not carving deep. You are peeling a thin cap layer cleanly. That’s why higher speed, correct focus, and a sensible line interval usually beat “slow and hot.”
Best lookFast + shallow + clean exhaust
Common failureSlow + overheated edges

Quick answer

For most 2 mm two-color acrylic sheets, start with a single shallow raster pass at medium–high speed, keep focus on the top surface, and use a line interval that supports clean overlap without over-heating.

  • Material thickness: 2 mm (typical signage stock)
  • Lens: 50 mm
  • Power: 50–70% (then fine-tune)
  • Speed (by wattage): see the table below
  • DPI: 400–600 (text/graphics)
  • Recommended line interval: 0.12–0.15 mm for crisp lettering (adjust for your machine)
  • Workbed: honeycomb (reduces back-reflection marks)
  • Air assist: medium to low; reduce if letters turn gray/fuzzy
Rule of thumb: If edges look melted, your process is too hot. Increase speed first. If removal becomes patchy, add a small amount of power or slightly reduce speed—avoid “slow and hot” whenever possible.

What two-color acrylic is (and what it is not)

Two-color acrylic (also called two-ply, dual-layer, or engraving plastic) is built for signage. It typically has a thin top cap layer (Color A) bonded to a contrasting base layer (Color B). Your CO₂ laser removes the cap to reveal the base color beneath—instantly producing high-contrast text and graphics.

This is why two-color sheets can feel “easy” when the settings are right: there is no paint fill, no post-coloring, and minimal finishing. But when settings are wrong, the failure modes are very obvious: melted edges, fuzzy text, gray haze, and residue trapped in fine corners.

Where it’s used most:
  • Store logos, desk nameplates, door signs
  • Control panels, machine plates, serial/UID labels
  • Wayfinding, safety signage, equipment tags
Not all “engraving plastic” is the same. Some brands are acrylic-based, others are modified plastics. That means you should treat any published settings as starter settings and validate with a small test on your own stock.

Starter settings for 2 mm (by wattage)

Below is a practical, production-focused starting point for 2 mm two-color sheets. Your goal is clean cap removal with minimal heat input. If you need to “push harder” to remove the cap, do it with small power increases—not by slowing down too much.

Laser Power Class Starter Speed Starter Power Notes
60 W CO₂ 13–15 mm/s 60–70% Good clean lettering; keep it shallow; test airflow lower if haze appears
100 W CO₂ 20–25 mm/s 55–65% Stable balance; usually a single pass is enough for signage work
130–150 W CO₂ 35–50 mm/s 50–60% Fastest and often sharpest; higher speed reduces melting and corner rounding
DPI and line interval are linked. If you engrave at 400–600 DPI but your line interval (scan gap) is too tight, you can overheat the cap layer and soften edges. Start with 0.12–0.15 mm and adjust based on the symptom.

Software must-know: speed units & line interval

1) Confirm your speed units (mm/s vs mm/min)

Many people “copy the right settings” and still get bad results because the software unit is different. Some programs show engraving speed in mm/min, others in mm/s.

  • If your speeds look like 3000–20000, that is likely mm/min.
  • Conversion: mm/s × 60 = mm/min (so 20 mm/s = 1200 mm/min).

2) Line interval (scan gap) is the “secret” to crisp letters

For two-color acrylic, line interval often matters more than people expect—especially on small text and fine details. Too much overlap (too tight interval) increases heat and can create gray haze and rounded corners. Too little overlap (too wide interval) can look patchy.

Start here:
  • 0.12–0.15 mm line interval for most signage text
  • If letters look gray/fuzzy: increase line interval slightly (less overlap) and reduce air assist
  • If fill looks striped/patchy: decrease line interval slightly (more overlap) or add a small amount of power

3) Use a 30-second speed ladder test

Instead of guessing, create a tiny test plate (a small filled square + a line of text) and engrave 3–5 rows at different speeds while keeping power fixed. Choose the fastest row that still removes the cap cleanly. This quickly reveals your stable “clean lettering” window for that sheet batch.

Lens & focus: why slight defocus can help

A 50 mm lens is a common default for signage. The two biggest focus mistakes are: (1) focusing below the surface and (2) trying to engrave too deep. Two-color acrylic likes a clean “surface peel.”

Parameter Recommendation Why it matters
Lens 50 mm Good balance of detail + working distance for signs
Focus Top surface Cap layer is the target; focusing too low adds heat and melts edges
Optional defocus +0.2 to +0.3 mm Softens peak energy density; can reduce edge melting and corner rounding
DPI 400–600 Enough for crisp text; higher DPI increases dwell/time and heat
If your text corners look rounded: you are almost always too hot (too slow, too much overlap, or too much power). Increase speed and/or increase line interval slightly before adding power.

Air assist & workbed: avoid gray haze and reflection marks

Air assist is useful for smoke removal, but too much airflow can cool the surface unevenly and push residue back into fine text. For two-color acrylic, many operators get cleaner letters with moderate-to-low air assist rather than maximum blast.

Air assist strategy

  • Start with medium airflow.
  • If letters look gray/fuzzy, reduce airflow and test again.
  • A slight side-angle nozzle can be cleaner than a straight-down jet.
  • Ensure your exhaust is strong—good extraction matters more than brute air assist.

Workbed setup (why honeycomb is preferred)

  • Best: honeycomb bed—helps airflow and reduces back-reflection marks.
  • Avoid placing the sheet directly on flat metal—reflections can cause dirty shadows on the back or around fine text.
  • Keep the sheet flat and secured—vibration or “chatter” can fuzz edges.
Shop Honeycomb Tables

Artwork prep for clean, readable text

Two-color acrylic is most impressive when the design is legible at a glance. That means you should treat artwork preparation as part of the process window—not as an afterthought.

Practical design rules for signage
  • Bold fonts engrave cleaner than thin serif fonts at small sizes.
  • Minimum stroke width: keep strokes ≥ 0.15–0.25 mm when possible.
  • Use solid fills for text/graphics; avoid “hairline” details unless you have verified them by test.
  • Raster engraving is typically “black = engrave, white = keep.”
  • For fine logos, prioritize clean shapes over excessive tiny texture.

Raster vs vector (when to use each)

  • Raster is best for filled text, icons, and solid areas.
  • Vector is best for outline cuts, contour marks, and sharp edges around the perimeter.
  • A common workflow is: raster engrave first (cap removal), then vector cut the sign shape.

Step-by-step workflow (from test to production)

This workflow helps you lock in clean results quickly and keep them stable during production runs.

  1. Confirm material: verify you are using a two-color sheet intended for laser engraving (avoid unknown PVC-based plastics).
  2. Prepare the workbed: use honeycomb, ensure the sheet is flat, and check exhaust.
  3. Set focus: focus on the top surface (cap layer).
  4. Load starter settings: select your wattage row from the table above.
  5. Run a small test: engrave a corner test (text + filled square) and evaluate contrast and edge quality.
  6. Tune with rules: use the troubleshooting rules below (speed first, then line interval, then power).
  7. Engrave the full plate: keep consistent sheet orientation and clamp method.
  8. Clean and finish: brush dust, wipe with IPA/alcohol, apply adhesive/backing if needed.
Tuning order that prevents mistakes: change speed first → then line interval → then power. This order keeps heat under control and avoids “slow and hot” failures.

How to get sharper letters (6 practical tweaks)

If your engraving “works” but still looks slightly fuzzy or dirty, these six tweaks usually make the biggest difference—without turning your process into trial-and-error.

  • Increase speed: the fastest clean cap removal usually looks the sharpest.
  • Reduce air assist: if haze appears, lower airflow and rely on good exhaust.
  • Adjust line interval: start 0.12–0.15 mm; increase slightly for haze, decrease slightly for patchiness.
  • Try slight defocus: +0.2–0.3 mm can reduce edge melting on small text.
  • Reduce DPI if overheating: very high DPI increases dwell time and heat.
  • Improve bottom airflow: honeycomb + clear exhaust path reduces residue redeposit.

Troubleshooting: symptom → cause → fix

Use this table as a fast diagnostic. The fixes are listed in the order you should try them.

Symptom Most likely cause Fix (do this first → then)
Edges look melted / corners rounded Too much heat (slow speed, too much overlap, too high power) Increase speed → increase line interval slightly → reduce power / try slight defocus
Text looks gray or hazy Residue redeposit / too much air blast / weak exhaust Reduce air assist → improve exhaust → increase line interval slightly
Engraving is patchy / incomplete cap removal Not enough energy (too fast / too low power / interval too wide) Decrease speed slightly → add a small amount of power → reduce line interval slightly
Backside shadows / dirty marks Back reflection from flat metal surface Use honeycomb → raise on pins/stand-offs → avoid flat reflective plates
Fine text looks fuzzy Focus off / too much heat / too much airflow Refocus on top surface → increase speed → reduce airflow / try slight defocus
Deep groove you can feel Over-engraving (too hot or too many passes) Use 1 pass → increase speed → reduce power

Safety & material warnings (PVC, fumes)

Do not laser cut or engrave PVC-based sheets. PVC can release toxic and corrosive chlorine compounds. If your sheet is unknown, verify the material or source it from a reputable supplier.
  • Use strong ventilation and proper exhaust filtration if required.
  • Do not leave the laser unattended during operation.
  • Keep optics clean—dirty lenses can cause power instability and edge defects.

FAQ

Q: Does two-color acrylic need deep engraving?
No. You only need to remove the thin top cap layer to reveal the contrasting base color.

Q: Do I need masking film?
Not required, but masking can reduce cleanup. Peel it after engraving.

Q: Can a 60W CO₂ laser engrave two-color acrylic well?
Yes. Start slower (around 13–15 mm/s for 2 mm stock) and tune using a small test and the troubleshooting rules above.


Contact us for more information See CO₂ Laser Cutters

If you want to go deeper (materials, cleaner edges, and repeatable settings), these guides are a good next step:

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